NC-2009 WEc2: Innovative Wastewater Technologies

  • NC CS Schools WEc2-Type3-Wastewater diagram
  • Two options, but three choices

    The intent of this credit is to reduce the amount of potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. used for flush fixtures and to minimize the amount of wastewater conveyed to the municipal system. For credit compliance, you have two options: 

    Option 1: Reduce the quantity of potable water used for flush fixtures (water closet and urinals only) by 50%. You have two ways to make this reduction:

    • use low-flow fixtures;
    • use non-potable water such as graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. or rainwater, or combine both strategies.

    Option 2: Treat 50% of wastewater onsite to tertiary standards and infiltrate it, or reuse the treated wastewater onsite. 

    Establish a baseline

    To determine your percentage reduction, compare a baseline case with the design case. Note that the baseline for WEc2 is not the same as the baseline for WEp1 and WEc3: Water Use Reduction. Whereas WEp1 and WEc3 count flow (shower, lavatory and kitchen sink) and flush fixtures (toilets and urinals), WEc2 only counts toilets and urinals. The data that you enter on flush fixtures in the LEED Online credit form in WEp1 will automatically populate the credit form for WEc2. 

    The calculations for wastewater use are based on the number of full-time equivalentFull-time equivalent (FTE) represents a regular building occupant who spends 40 hours per week in the project building. Part-time or overtime occupants have FTE values based on their hours per week divided by 40. Multiple shifts are included or excluded depending on the intent and requirements of the credit. (FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories.) occupants. FTE calculations can sometimes be confusing in certain building types or occupancy types—see WEp1 for more information. 

    Fixture choice is the cheapest option, if you can make it work

    Generally, the easiest and cheapest way to achieve this credit is to install low-flow and waterless fixtures. Using waterless urinals or pint-per-flush urinals in combination with ultra-low-flow toilets (1.0 gpf) or aggressive, dual-flushA type of water-saving toilet that gives a choice of flushes depending on the type of waste — solid or liquid. toilets (1.28/0.8 gpf) can work, although it depends on your project occupancy and will need to be verified for each project.

    If your project comes up just a little short, consider supplementing some of your potable water use with graywater or rainwater, or installing composting toiletsComposting (or Nonwater) toilet systems are dry plumbing fixtures and fittings that contain and treat human waste via microbiological processes.

    Treating wastewater onsite is great—if it’s right for your project

    Onsite wastewater treatment has a number of environmental and educational benefits, but treating to tertiary standards can be challenging for some projects, especially if they have limited space. The Solaire, a LEED Gold market-rate apartment building in Battery Park City in Manhattan, located wastewater treatment facilities in the basement because above-grade space was at a premium.

    Treating to tertiary standards involves extra filtration or biological activity to remove nutrient pollutants such as nitrogen and phosphorus, and it may also involve disinfection. Treating wastewater to this level goes beyond code in most places. Consider technologies that are passive or low-tech in order to minimize operation and maintenance costs.

    Once the wastewater has been treated to tertiary standards, you’ll need to determine the best reuse method. Many projects prefer to use it landscape irrigation. This will generally be your cheapest and easiest reuse method. If your project doesn’t have landscaping, consider reusing the treated wastewater for toilet flushing.

    Notes on specific building types

    Office—In order for office spaces or other buildings to meet the credit through fixtures alone, they will most likely need to include waterless urinals. (Depending on your project, one-pint-flush urinals may work.)

    Multifamily and Hotel—Residential and hotel projects, which don’t have urinals in private bathrooms, cannot meet this credit with low-flush fixtures alone, so they have to provide nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. or treat wastewater on site to earn the credit. 

  • FAQs for WEc2

    The credit language says the Option 2 involves a reduction in wastewater. Does that mean that all water, including process water, should be included?

    The WEc2 calculations are based on the annual generation of blackwaterBlackwater is wastewater containing urine or fecal matter that should be discharged to the sanitary drainage system of the building or premises in accordance with the International Plumbing Code, or sewage, from flush fixtures as documented in WEp1. Note that the scope is not the same as WEp1, which includes both flush and flow fixtures.

    Can project teams include reclaimed water systems that are planned and funded, but not completed?

    Yes, per LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #10012 made on 05/09/2011, "projects may only count future infrastructure such as reclaimed water systems so long as they will be completed and functional within 1 year." Anything further out than one year may not be counted, however.

Legend

  • Best Practices
  • Gotcha
  • Action Steps
  • Cost Tip

Pre-Design

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  • Check for local or state incentives for water conservation, which can make this credit more feasible. Rebates are common. Also, some municipalities offer treated wastewater to buildings, which may be used for toilet flushing (although in most places it is restricted to landscape use). 


  • Perform a water-balance study for the entire project in order to make an informed decision about where to focus your water-saving efforts. Survey your project and site for all water sources—stormwater, graywater, and onsite wastewater. 


  • Calculating irrigation water use is not required for this credit; however, understanding how indoor water use compares to outdoor water use can help you gauge where to focus your reduction efforts for the greatest benefit. Some water-saving strategies address both indoor and outdoor water needs holistically. For example, if you treat your wastewater onsite, you can use the treated water to irrigate your landscape as well as to flush toilets. Doing so can contribute to either WEc1: Water Efficient Landscaping or WEp1 and WEc3: Water Use Reduction.


  • Establish goals for indoor and outdoor water and wastewater reduction. You may want to include those goals in the Owner’s Project Requirements for EAp1: Fundamental Commissioning and EAc3: Enhanced Commissioning.


  • Consider reducing potable wastewater use by 100%, or treating 100% of your wastewater onsite to tertiary standards, for an Exemplary Performance point. 


  • Determine which option is best for your project:

    • Option 1, with a focus on fixtures alone, is often the easiest and cheapest way to earn the credit. However, your project must be able to install waterless or pint-per-flush urinals as well as ultra-low-flow toilets (1.0 GPF) or low-flow, dual-flush toilets (1.28/0.8 gpf) to have a shot. You may fall short with just fixture selection and need to incorporate graywater or rainwater reuse in order to meet the 50% reduction. For example, if you install waterless urinals and typical dual flush toilets (1.6/0.8 gpf) you will most likely only achieve a 45% reduction, and will need to make up the extra 5% with nonpotable water use. If that’s the case, you may need to involve a civil engineer, and achieving the credit becomes more complicated. 
    • In Option 2, you’ll need to treat 50% of onsite wastewater to tertiary standards and reuse or infiltrate the treated wastewater on-site. This option requires the involvement of a civil engineer, additional space (either in the building basement or onsite), and willing maintenance personnel. You may find the educational and environmental benefits of onsite wastewater treatment are worth the extra work. Benefits include reduction of wastewater demand for the municipality, and opportunities to reduce the use of potable water for irrigation or toilet flushing. The treatment system can also function as an amenity and an educational facility.

  • Some municipalities requiring rainwater capture to reduce stormwater runoff; if this is the case in your area, consider reusing the rainwater for toilet flushing. 


  • Reusing graywater or rainwater incurs additional costs and requires dual plumbing. If you use an under-sink graywater system that shunts the water directly from the sink to the toilet, this also involves additional cost but may be less expensive than a centralized, dual-plumbed system. 


  • Onsite wastewater treatment costs vary widely. Treating to tertiary standards, as required by this credit, can cost significantly more than treating to secondary standards. 


  • Determine if composting toilets or waterless urinals are appropriate for your project. While not common, waterless fixtures can go a long way toward achieving this credit. Composting toilets do affect programming and layout, however, so be sure to consider them early in the planning stages. However, projects often find that installing only a few composting toilets can help them to achieve this credit while offering a great educational asset. 


  • Check with the local municipal wastewater department to see if reclaimed water is available as a source of non-potable water for toilet flushing. If it is available, this will contribute to compliance with Option 1. 


  • Check for codes that may limit your options or force you to obtain a variance. Plumbing codes often restrict or regulate the following water-saving technologies: 

    • waterless urinals
    • graywater reuse
    • onsite wastewater treatment and reuse
    • rainwater reuse
    • composting toilets. 

Schematic Design

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  • Determine your project’s baseline case wastewater generation. This will help you develop your strategy for reduction. 


  • When using the LEED Online credit forms, you need to complete the WEp1: Water Use Reduction—20% Reduction credit form first. Doing so automatically generates your baseline-case usage in WEc2. (See WEp1 for details on determining occupancy, usage, and FTE.) 


  • Reducing your shower or sink flow rate will not help with credit compliance for WEc2 but, will help with WEp1 and WEc3. However, if your project is earning this credit through treating wastewater onsite, it is best to reduce the total quantity of water being treated. Therefore, a reduction in flow fixtures will minimize the total water needing treatment. 


  • Begin developing your strategy for wastewater use reduction based on the option you’ve selected. Research low-flush fixtures, water reuse, and onsite treatment. 


  • Well and pond water are not considered non-potable water for the purposes of this credit and must count as potable water—so you won’t get credit for substituting them for conventional water sources. Water types that do count as non-potable are: graywater (lavatory, sink, and shower water), rainwater, treated wastewater, air-conditioner condensate, reverse-osmosis reject, and sump-pump water. 


  • Consider monitoring wastewater reduction in conjunction with EAc5: Measurement and Verification.


  • Consider installing permanent water metering for ongoing monitoring of the project’s water use. A submetering system can help operations staff detect problems early and facilitate future LEED-EBOM certification. 

Design Development

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  • Option 1: Reduce Potable Water Use for Building Sewage Conveyance by 50%


  • Select water-efficient flush fixtures and determine the percentage of reduction from fixtures alone. 


  • Consider the different maintenance requirements for waterless fixtures. Waterless urinals and composting toilets require a different maintenance program from conventional fixtures.


  • Remember that this credit is based on EPAct 1992 and subsequent rulings of EPAct 2005, the 2006 Uniform Plumbing Code, and the International Plumbing Code. The baseline case for this credit includes these standards:

     


  • Track and record information on applicable fixtures, including the manufacturer, model number, and flush or flow rate. This will help you when filling out the LEED Online credit forms. Fill out the LEED Online form early in design simply as a draft to determine if you are meeting the requirement. 


  • Typically, a dual-flush toilet—with the heavy-flow at 1.6 GPF and low-flow at 0.8 GPF—does not meet the credit requirements. However, a 1.0 GPF ultra-low-flow toilet or a 1.28/0.8 GPF dual-flush toilet—in conjunction with waterless or pint urinals—will meet the credit requirements, and you can avoid using non-potable water. For occupancies that do not use urinals, such as residences or hotels, you will not be able to meet this credit through the use of fixtures alone and you’ll find that you have to include non-potable water reuse in your water reduction strategy.


  • If you cannot meet the credit through the use of fixtures alone, determine how much non-potable water you need to use in order to comply. 


  • Review your water balance study and determine what water reuse would be most appropriate for your project. If the building is residential or a hotel, it might be best to treat and reuse graywater from laundry or shower facilities. If the building is located in a rainy climate, you can capture and reuse rainwater. 


  • If needed, size graywater and rainwater systems to satisfy the credit requirements. Sizing these systems can be more complicated than you might initially think. It’s best to involve a civil engineer or someone familiar with these systems. 


  • Untreated rainwater and graywater may corrode plumbing systems or lead to biological growth. You should plan for water treatment and filtration, or use corrosion-resistant materials. All graywater plumbing and storage must be separate from regular sewage plumbing.


  • If you will be using graywater, rainwater, or treated wastewater, you’ll need dual plumbing for interior water fixtures. Communicate this need to your civil and plumbing engineers. You should also discuss any location and structural issues if your project is going to have a rainwater cistern—sometimes they take up more space than anticipated.


  • A dual plumbing system and rainwater or graywater reuse are likely to add upfront costs but the owner may recoup some of that cost in reduced water and sewer charges. However, most current utility rates for water and sewer are too low to justify these systems on a cost basis alone. 


  • Typically, dual-flush and composting toilets have a higher cost over conventional fixtures but reduce water charges. Some ultra-low-flow toilets have a cost premium as well, but it is typically not as significant as a dual-flush or composting toilet. 


  • Compare the baseline and design case water budgets to determine the water reduction percentage for your project. The LEED Online credit form has a built-in calculator to facilitate this calculation. Repeat this process until selection of water fixtures and strategies is finalized and your project’s water reduction goals have been met. 


  • Option 2: Treat 50% of Wastewater Onsite to Tertiary Standards


  • Even if you are attempting Option 2, you will want to select water-efficient fixtures, which minimize the quantity of wastewater treated onsite. To accomplish this, target the most consumptive fixtures to achieve the greatest water reduction, but keep in mind the very different maintenance requirements for waterless fixtures. See WEp1 and WEc3: Water Use Reduction for more information. Also, review the Option 1 steps of this credit.


  • Determine what type of onsite wastewater treatment is most appropriate for your project. Typical septic-tank-and-leachfield systems used in many rural areas where there are no sewer systems do not treat water to tertiary standards so they can’t be used to earn this credit. 


  • Verify that your onsite wastewater treatment system is capable of treating the wastewater to tertiary standards. State governments determine exactly what constitutes “tertiary treatment” based on allowable remaining levels of certain nutrients and organisms. Your civil engineer will need to be in charge of this determination. 


  • Determine how treated wastewater will be used onsite. It must either be reused, such as for toilet flushing or irrigation, or must be infiltrated onsite. 


  • Treating wastewater simply for sewage conveyance can be expensive, so make the most of tertiary-treated wastewater by using it for as many non-potable water applications as possible—irrigation, toilet flushing, and cooling tower makeup water.


  • While the capital cost of wastewater treatment is a significant deciding factor, seek technologies or strategies that have low maintenance requirements to keep operations and maintenance costs low. Alarm systems for malfunctioning wastewater treatment systems can be expensive, be sure to research this. 


  • Depending on the technology used and state or local regulations, tertiary wastewater treatment may require contracting with an outside company for operations and maintenance. When researching treatment technologies, inquire about maintenance procedures and requirements. 

Construction Documents

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  • Include any low-flow or waterless fixtures, water reuse systems, or onsite wastewater treatment systems in your construction and design development documentation. 


  • Be certain that the contractors reviewing construction documents understand the purpose of any dual-plumbing system in the plans. Misunderstandings about plumbing can lead to costly and unsanitary mistakes—like cross-connection with potable water lines. 


  • Consider including signage for water reduction strategies that may require special instructions for use. These may include: occupant signage for operating dual-flush toilets, waterless urinals and composting toilets, and for indicating non-potable water—and operational signage for distinguishing the pipes that carry reused water. Purple piping is commonly used for reclaimed water and, more recently, for recycled graywater.


  • If reusing graywater or rainwater, or treating wastewater onsite, ensure that the key system components, such as treatment and collection facilities, are not eliminated during value engineering. 


  • Option 1: Reduce Potable Water Use for Building Sewage Conveyance by 50%


  • Fill out the LEED Online credit form. The total calculated flush-fixture water-use for the baseline and design cases will be automatically generated once the WEp1 credit form is filled out. You will need to provide information on annual reused water amount and, and if necessary, plumbing drawings or calculations illustrating that your non-potable water systems are capable of supporting the quantities determined. 


  • Option 2: Treat 50% of Wastewater Onsite to Tertiary Standards


  • Fill out the LEED Online credit form. The total calculated flush-fixture water-use for the baseline and design cases will be automatically generated once the WEp1 credit form is filled out. You will need to provide information on the blackwater source (toilet or urinal), annual quantity treated, annual quantity infiltrated onsite, annual quantity reused onsite, and plumbing drawings or other documents that detail information about the onsite treatment, infiltration, and reuse capabilities of your project. 


  • Be sure you’ve included startup of a wastewater treatment system in contract documents and scope of services. You may want the commissioning agent to look at the wastewater treatment system too.

Construction

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  • The contractor needs to verify that the correct fixtures have been purchased and that applicable water reuse or treatment systems have been installed properly. 


  • Be sure to use purple pipes or otherwise clearly label supply pipes carrying non-potable water. This practice avoids inadvertent cross-connection with potable water lines and provides educational value. 


  • When using an innovative wastewater treatment system unfamiliar to local regulatory officials, include them in regular construction inspections. This often helps to ease acceptance, and avoid unexpected objections or problems. 

Operations & Maintenance

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  • Apply for water-reduction incentives and rebates through your municipal water authorities. 


  • Provide building managers with manuals for all water fixtures, water reuse technologies, onsite water treatment systems, and unconventional products used. 


  • If a submetering or ongoing monitoring system is in place, be sure to track and record monthly use. This can help detect problems, contribute to a comprehensive M&V plan, and help with LEED-EBOM certification.


  • Train cleaning and operations staff to maintain atypical fixtures such as waterless urinals, composting toilets, and graywater collection and rainwater catchment systems. 


  • Some wastewater treatment systems require trained personnel to operate them.

  • USGBC

    Excerpted from LEED 2009 for New Construction and Major Renovations

    WE Credit 2: Innovative wastewater technologies

    2 Points

    Intent

    To reduce wastewater generation and potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. demand while increasing the local aquifer recharge.

    Requirements

    Option 1

    Reduce potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. use for building sewage conveyance by 50% through the use of water-conserving fixtures (e.g., water closets, urinals) or nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. (e.g., captured rainwater, recycled graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area., on-site or municipally treated wastewater).

    OR

    Option 2

    Treat 50% of wastewater on-site to tertiary standards. Treated water must be infiltrated or used on-site.

    Potential Technologies & Strategies

    Specify high-efficiency fixtures and dry fixtures (e.g., composting toilet systems, nonwater-using urinals) to reduce wastewater volumes. Consider reusing stormwater or graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. for sewage conveyance or on-site mechanical and/or natural wastewater treatment systems. Options for on-site wastewater treatment include packaged biological nutrient removal systems, constructed wetlands and high-efficiency filtration systems.

Publications

Terry Love’s Consumer Toilet Reports

This website offers a plumber’s perspective on many of the major toilets used in commercial and residential applications. 

 


Water Closet Performance Testing

This site provides two reports on independent test results for a variety of toilets’ flush performance and reliability.

 


American Rainwater Catchment Systems Association

ARCSA was founded to promote rainwater catchment systems in the United States. The ARCSA website provides regional resources, suppliers, and membership information, and publications such as the Texas Guide to Rainwater Harvesting

 

Technical Guides

US EPA, On-Site Wastewater Treatment Systems Manual

This manual provides a focused and performance-based approach to on-site wastewater treatment and system management. It also includes information on a variety of on-site sewage treatment options. 

 

Organizations

WaterSense

WaterSense is a U.S. Environmental Protection Agency program designed to encourage water efficiency in the United States through the use of a special label on consumer products. It was launched in 2006. The WaterSense website offers information on certified products, and other water conservation information from its partners.

Example Calculations

The LEED Online credit form offers a useful calculator for this credit that we recommend. The scenarios shown in these sample calculations show how this credit can play out with percentage savings based on fixture selection alone.

LEED Online Forms: NC-2009 WE

The following links take you to the public, informational versions of the dynamic LEED Online forms for each NC-2009 WE credit. You'll need to fill out the live versions of these forms on LEED Online for each credit you hope to earn.

Version 4 forms (newest):

Version 3 forms:

These links are posted by LEEDuser with USGBC's permission. USGBC has certain usage restrictions on these forms; for more information, visit LEED Online and click "Sample Forms Download."

Design Submittal

PencilDocumentation for this credit can be part of a Design Phase submittal.

103 Comments

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Valentin Grimaud Thermal Engineer TERAO Green Building Engineering
Mar 27 2014
LEEDuser Member
715 Thumbs Up

Non-potable water for sewage conveyance required for option 1?

Dear community,

We have pursued this credit with option 1 and have achieved 52.31% only with the use of high efficiency WC and urinals.
Now, the reviewer has sent very weird comments for this credit stating that we have not demonstrated the non-potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. available for sewage conveyance. Well of course not because we do not plan to.
There is rainwater collection in this project but only for irrigation purpose. And he does mention that we have provided documentation for WEc1 to confirm the availability of the quantity of the non-potable water claimed. This is true but we have demonstrated this quantity only to earn credit WEc1, nothing to do with WEc2.

I am very tempted to think that the reviewer got confused between the credits and our intent in using rainwater but before I answer that, I would like to know if someone has encountered the same issue.

With many thanks,

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Devani PERERA Green Building Consultant, ELAN Mar 27 2014 LEEDuser Member 223 Thumbs Up

Hello,
I have used the same strategy on projects and never been asked this question. Using treated water is one of the strategies not the only one to meet the requirements of this credit. Did you check the PI forms to see if there were any forms that indicated treated water? There has to be a reason for this confusion. Good luck and keep us posted.
Devani

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JOHANNA SENOTT Architect / Environmental adviser EA Energia y Arquitectura
Jan 22 2014
LEEDuser Member
483 Thumbs Up

Treated (rain) water for human contact...

Here is a situation:

Rain water is captured and treated for reusing to flush and flow fixtures.
A single cistern storages both rainwater and municipal water supply. From this cistern, water goes through treatment and a different cistern storages treated water.
Since treated rain water is being reused to flow fixtures, would it be classified as potable?
And if so, does it count to WEc2 compliance?
My conflict is that, at the end, potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. would be used to flush fixture, however it is captured and treated rainwater.

Any thoughts?

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Amy Rider Sustainability Manager, KEMA Services Feb 04 2014 LEEDuser Expert 1726 Thumbs Up

Johanna,
I think you would be meeting the intent of the credit by using rainwater for this purpose. As a result WEc2 shouldn't be a problem as long as you are also using high efficiency fixtures.
However, I wonder how much of the water is going to flush fixtures and if there is a way to not treat all of it in the first place.
Amy

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Joann Lee Heitman Architects Inc.
Dec 20 2013
LEEDuser Member
101 Thumbs Up

rainwater for greenhouse food production

We are designing an 150,000 sf industrial production facility in Chicago with a greenhouse on the roof for food production. A cistern is proposed to collect rainwater from the roof, have it treated and used to meet >50% water demands of the greenhouse production. Does this qualify for WEc2 at all? Greenhouse water is considered a process load, but it certainly reduces potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. usage. Additionally there's a state moratorium on using rainwater for toilets and urinals in Illinois. Also, we have reached the maximum 5 points on ID through other sustainable features and exemplary points, so ID option is out.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 20 2013 LEEDuser Moderator

Joann, I think this is covered under the first FAQ above. Please post back here if that doesn't do it for you.

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Joann Lee Heitman Architects Inc. Dec 20 2013 LEEDuser Member 101 Thumbs Up

Thanks, Tristan. But I just can't believe that the LEED wouldn't recognize the benefit of rainwater being used for greenhouse. Perhaps a few versions down the road.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 20 2013 LEEDuser Moderator

Joann, my answer was in response to your question on WEc2. Taking a broader view, you could get recognition for this under WEc3—see our last FAQ on the page there.

And you need look no further than the next version of LEED, LEED v4, for an even more integrative approach to water savings under IPc1.

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Aru Sau
Dec 02 2013
Guest
13 Thumbs Up

water balance report

Howdy!
Looking for some information about water balance report. Is there any ready made tools available which I can use for LEED? Could any provide some more information about water balance reporting, so I can create a spreadsheet tool and share.

Thanks!
Aru

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Dec 20 2013 LEEDuser Moderator

Aru, I am not aware of any ready-made tools for buildings. Please let us know if you find anything good, or make something.

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Yasir Nurrahman Mr. Yasir PT. Indonesia Environment Consultant
Nov 18 2013
LEEDuser Member
566 Thumbs Up

Determination of nonpotable water

In general, buildings in our country usually get clean water from PDAM (the municipal water system), and this clean water have a quality standard that is not equal (below) to EPA's drinking water quality standard (we simply can't drink water straight from the tap).
For drinking water, our people usually have to buy bottled drinking water or sometimes must boil PDAM's clean water first before they can drink the water). In some cases, people still complain about the clean water they got (e.g. iron odor, etc.). From your perspective, do you think our so-called clean water can be categorized into nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. by the LEED reviewers?

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Amy Rider Sustainability Manager, KEMA Services Nov 18 2013 LEEDuser Expert 1726 Thumbs Up

Hi Yasir,
I think you have a good case for claiming your "so-called clean water" as non-potable for GBCI purposes under their definition of, "Water that is unsafe or unpalatable to drink", however I am unclear how this helps your project. Before making the declaration that all of your project uses nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. I suggest you review the credit impacts carefully.

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Yasir Nurrahman Mr. Yasir, PT. Indonesia Environment Consultant Nov 19 2013 LEEDuser Member 566 Thumbs Up

Thanks for the reply Amy,
I'm just wondering if it'd be approved as nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. by the GBCI, because all I see is that the nonpotable water considered by GBCI is either rainwater, graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area., cooling system condensate, or municipal treated wastewater, not from the municipal water system itself. And yes, if we could claim this as nonpotable water, we intend to use that as proof that we could reduce the potable water use for sewage by 100%.

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Amy Rider Sustainability Manager, KEMA Services Nov 21 2013 LEEDuser Expert 1726 Thumbs Up

Yasir,
I would be surprised if claiming nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. as your supply water earns you extra credits. Even though no potable water would be used for sewage conveyance you haven't technically reduced/eliminated it. This claim may instead render you ineligible for the indoor water credits.
Does anyone else have experience with this?

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Yasir Nurrahman Mr. Yasir, PT. Indonesia Environment Consultant Nov 24 2013 LEEDuser Member 566 Thumbs Up

Amy,
That's why I asked this question in the first place, whether GBCI accept municipal water as nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. and whether a project can get extra point for this credit, as I also thought that this approach might not considered technically reduce/eliminate potable water use by GBCI.
I just thought that with so many international project and each country have a variety of municipal water system running or drinking water quality level. Maybe it's better that later, GBCI have an alternative definition of potable water. But, it's just an opinion though.

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Sam Farmer Green Fields
Oct 09 2013
LEEDuser Member
43 Thumbs Up

0.8 gpf water closets, no urinals

We have a project that is considering a 0.8 gpf water closet. The project is an existing building renovation and we do not have ADA clearance space for the addition of urinals. Since the baseline for WC's is 1.6 gpf, does this strategy qualify for WEc2? Completing the template for WEp1 with WC's only registers 2pts for WEc2, but I feel without urinals, we are consuming more water for male uses than the USGBC might be expecting. Does our baseline only consider the type of fixtures we have installed? Thanks!

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 03 2013 LEEDuser Moderator

The reality is that the credit savings are based on fixture usage, not usage per a group of people, so I think your savings here are valid. 

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John Covello LEED and Sustainability Manager Development Management Group
Aug 02 2013
LEEDuser Member
244 Thumbs Up

Use of rainwater collected offsite

Our project is considering creating a retention pond for rainwater on land adjacent to the LEED project. They may develop the land where the pond is located so it cannot be included in the project boundary. Can this water still be used to meet the requirements of Option 1?

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Michael DeVuono Senior Staff Designer, T&M Associates Aug 02 2013 LEEDuser Expert 1937 Thumbs Up

I am curious about this as well.

The USGBC guidance for campus projects requires that the land be under the same ownership or management. In order to do this, you would likely be creating an easement for this pond, correct? At face value, I do not see a problem with this, as the intent of the credit is to reduce potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. usage, but I will defer to someone with a more definitive response.

Will the development of the adjacent property effect the pond you are creating? What I am getting at, is I think you will need to at least show that the pond will not be altered in a way that will hinder your ability to obtain the water you need to pull from it.

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John Covello LEED and Sustainability Manager, Development Management Group Aug 02 2013 LEEDuser Member 244 Thumbs Up

Thanks for posting Michael.

There will be an easement connecting the properties. It is actually a public right of way. There will be easements on private land as well connecting the property to the LEED project.

The development would affect the pond. There is talk of building elevated structures over the pond. I have not looked into yet what the impact of that would be as it is just a preliminary consideration. But that would be designed so as to not affect using the water for the site. We are trying for zero net water use. The pond is at the bottom of a sloped hill on the west side, and an elevated road on the south side. The north and east side lie in the owners property (and the LEED project area) and they are relatively flat. It will catch a lot of rainwater from the elevated areas and be part of a system that will include bio swales and retention ponds located in the project boundary.

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John Covello LEED and Sustainability Manager, Development Management Group Aug 03 2013 LEEDuser Member 244 Thumbs Up

Hello Michael,

I found this language under WE Preq 1 Potential Strategies:

Consider using alternative on-site sources of water (e.g., rainwater, stormwater, and air conditioner condensate) and graywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. for nonpotable applications such as custodial uses and toilet and urinal flushing.

It would seem to be consistent with WE Prereq 1 this credit would require onsite water as well. But I am not seeing that referred to in the credit language.

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Michael DeVuono Senior Staff Designer, T&M Associates Aug 05 2013 LEEDuser Expert 1937 Thumbs Up

I was hoping someone else would have chimed in by now, but my gut is telling me that if you have an easement for use of this pond, and it's collected rainwater, you go for it. I wouldn't think the "on-site" language above would be binding.

You can ask for guidance from GBCI: http://www.gbci.org/org-nav/contact/Contact-Us/Project-Certification-Que...

They do take about 2 weeks to get back to you, so plan accordingly. Sorry I could not have been of more assistance. Let us know how you make out.

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Amy Rider Sustainability Manager, KEMA Services Sep 25 2013 LEEDuser Expert 1726 Thumbs Up

Finally chiming in on this string - I agree with Michael. The easement should give you sufficient control over the adjacent siteA site having at least 25% of its perimeter bordering sites that has been previously developed. Any fraction of the perimeter that borders waterfront will be excluded from the calculation. For the purposes of this definition, a street or roadway does not constitute previously developed land.'s rainwater functions to be acceptable to GBCI.

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Yasir Nurrahman Mr. Yasir PT. Indonesia Environment Consultant
May 20 2013
LEEDuser Member
566 Thumbs Up

water treatment outside LEED project boundary

Dear all,

We have a small LEED project (an office space with landscape) which located inside non-LEED construction project (factory), which will be conducted simultaneously. My question is, if the wastewater of the office buiding will be discharged out of the LEED project boundary into a WWTP on the factory site, treated and then streamed back to be infiltrated inside the LEED project, would this effort can met credit requirements for Option 2?

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Yasir Nurrahman Mr. Yasir, PT. Indonesia Environment Consultant May 31 2013 LEEDuser Member 566 Thumbs Up

Hello again,

I just wanted to update the above case. So, the owner have decided to install Sewage Treatment Plant to treat the wastewater from the office on-site , so there will be no issues with MPR3. However, they have proposed an STP design that it looks very good for treating the wastewater, but have no idea of the treated wastewater quality. The requirement does says that we must treat the wastewater to tertiary standard. Does this credit requires us to submit documentation on the quality of the treated wastewater? (This would mean we have to test the proposed design to know the quality result). Or is it possible if, just by providing the proposed STP design/drawing the reviewer can tell whether it can comply with the requirements?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 03 2013 LEEDuser Moderator

Yasir, the engineer should be able to state what quality the water is being treated to—this should not be left to the LEED reviewer to determine. 

It seems unusual the a system is being engineered but the designer has no idea of the resulting water quality. Shouldn't this be a design requirement for their work?

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Yasir Nurrahman Mr. Yasir, PT. Indonesia Environment Consultant Nov 14 2013 LEEDuser Member 566 Thumbs Up

Tristan, sorry for my previous post that is very disturbing. Actually, this case has been buried months ago. We found out that the STP system design was not made by the professional (hence, the no information of the resulting water quality), so we've decided not to pursue that option and select the Option 1 requirements using captured rainwater and treated wastewater.

By the way, buildings in our country, in general, usually get clean water from PDAM (the municipal water system), and this clean water have a quality standard that is not equal (below) to EPA's drinking water quality standard (we can't drink water straight from the tap like you. For drinking water, our people usually have to buy bottled drinking water or sometimes must boil PDAM's clean water first before they can drink the water). In some cases, people still complain about the clean water they got (e.g. iron odor, etc.). From your perspective, do you think our so-called clean water can be categorized into nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. by the LEED reviewers?

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Omar Katanani
Apr 18 2013
LEEDuser Member
6904 Thumbs Up

Rainwater collection and reuse on campus

Hello,

Our project is a new building on a school campus. The Engineers are proposing collecting rainwater from the building's roof, storing this is a big common water tank next to the building, and then reusing this water for flushing purposes for all buildings on campus.

So let's say the project building is collecting 200,000 gallons per year, and another building is collecting 300,000 gallons per year. These 500,000 gallons will be stored together and pumped to 3-4 buildings on campus (including those which they were collected from).

How can the collected rainwater contribute to the LEED water calculations of this project?

The Engineers are confident that all the collected rainwater will be used on campus, but they cannot be 100% sure all the collected rainwater will be used specifically on this building.

Any tips on the best way to proceed?

Thanks!

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Michael DeVuono Senior Staff Designer, T&M Associates Apr 18 2013 LEEDuser Expert 1937 Thumbs Up

Be sure to look into SS 6.1 and 6.2 as well if this reuse approach will be used.

I know there have been CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide's relating to campus-wide credit applications, I am not positive if WEc2 was one of them, but it is worth a look.

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Michael Wironen Ecology and Environment, Inc.
Mar 19 2013
LEEDuser Member
302 Thumbs Up

Combined approach to WEc2

We have a project where, through efficient fixtures, we will reduce wastewater (WCs, lavatories, and showers) conveyance by approximately 45%. This represents a significant reduction in potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. demand and sewage conveyance. At the same time, we are capturing all greywater, treating it to tertiary standards, and using it for irrigation. This further reduces sewage conveyance, for a net reduction in sewage conveyance by well over 50%. It seems like we are meeting the intent and performance threshold of the credit, yet we do not comply via either path. Has anyone tried this approach and succeeded in earning the points?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 19 2013 LEEDuser Moderator

Michael, you're overthinking it—you are meeting Option 1 through the combination of strategies mentioned in the credit language (see above).

Option 2 provides a way to comply with the credit without necessarily reducing the overall flow of wastewater. I do see how the language could be confusing.

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Michael Wironen Ecology and Environment, Inc. Mar 19 2013 LEEDuser Member 302 Thumbs Up

I may very well be overthinking it, but the credit language and form do not seem to allow our approach.

Per Option 1, you must reduce potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. use for sewage conveyance by 50%. We are reducing potable water use for sewage conveyance by 45% through efficient fixtures. We're then further reducing net sewage conveyance (but not potable water use for sewage conveyance) by diverting greywater from the sanitary sewer, treating it, and using it for irrigation.

The catch is we are not taking our treated greywater and using it to flush toilets or otherwise offset 'potable water for sewage conveyance.' We're using it to offset potable water for irrigation!

In any case, I think we'll submit a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide and see what response we get. I feel confident that we meet the intent although our approach does not seem to conform to the standard criteria.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 19 2013 LEEDuser Moderator

Michael, yes, I see you're right. I think that on the face of it, you would not meet the WEc2 requirements, but would have to take solace with a strong showing in WEc1 and WEc3, unless GBCI sees a path for you. Rather than submit a CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide, though, I'd start with contacting them via their website for a quicker opinion.

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Devani PERERA Green Building Consultant, ELAN Oct 16 2013 LEEDuser Member 223 Thumbs Up

Hello Michael,
You have reduced your potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. consumption by 45% using water efficient fixtures but the site treated water is not used to reduce the flushing needs. The project could have reduced further its potable water demand for flushing if treated water was injected into the system.
But I believe your project is eligible for the 2 points under option 2, which is to treat more than 50% of the waster water onsite to tertiary standards. If I understood your explanation correctly none of the water leaves the site and is reused for irrigation, therefore you should also obtain an exemplary point for WEc2 option 2.
Hope that helps.

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Mitch Gascoyne Manager, Sustaianable Design Services MCW Consultants Ltd
Mar 19 2013
LEEDuser Member
133 Thumbs Up

Water quality examples

Does anyone have a good resource for expected water quality/colour of collected rainwater for toilet flushing? I have a few photo examples but need some more to convince an owner to use the strategy.

Thanks,

Mitch

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 19 2013 LEEDuser Moderator

Mitch, I don't have any photographic examples, but in my experience it will typically look no different than regular toilet water. Rainwater itself looks like normal potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems.. It can pick up some particular matter or mineral coloration depending on the collection method and location, but some filtration can (and probably should) easily remove this.

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Michael E. Edmonds-Bauer Edmonds International
Mar 06 2013
LEEDuser Member
1188 Thumbs Up

One single treatment plant for two LEED projects

We have a project in which site two independent buildings will apply for LEED certification.

In this case, (when the treatment plant is shared by the two LEED buildings), is there any special consideration we need to take into account for the LEED certification process?

Building 1 + Building 2 will treat 100% of the waste water to tertiary standards.

100% of all treated water effluent will go to building 1 to supply water for cooling towers.

Will we be fulfilling WEc2 for the two LEED buildings?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 21 2013 LEEDuser Moderator

Michael, you haven't mentioned where the treatment plant is located, but I assume onsite. I think both buildings would be in compliance with WEc2. You will have some considerations to figure out with MPR3, but that seems doable.

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Michael E. Edmonds-Bauer Edmonds International Mar 21 2013 LEEDuser Member 1188 Thumbs Up

Hello Tristan,

For this project a LEED Boundary will be placed accordance to the property line. Whithin this LEED Boundary/property line the treatment plant will be located.

Both LEED Buildings will be located inside the LEED Boundary/property line.

So yes, the treatment plant will be on site. Thank you very much for your comments Tristan.

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Michael E. Edmonds-Bauer Edmonds International Mar 22 2013 LEEDuser Member 1188 Thumbs Up

Just in case someone is facing this situation, this was the GBCI response on this issue:

Dear David,

Thank you for contacting the Green Building Certification Institute about treating wastewater on a site with 2 buildings and using all of the water for the cooling tower in 1 building.

Appendix A to the
2010 LEED Application guide for Multiple Buildings and On-Campus Building Projects (AGMBC) October 31, 2011 , indicates, on page 14, that WEc2 can be pursued as a group credit but not as a campus credit.

If these 2 buildings will be built at the same time, under the same contract and using the same rating system, they may be certified as a group.

If that is not the case, then making a formal inquiry about a campus application may be worthwhile. It would require that you register a Master Site as well as the 2 projects. The argument to make is that you are treating 100% of the water from both buildings, and using all of it on the campus. Formal Inquiries may be submitted through LEED Online . Instructions can be found at this link; .

If you do not need the entire amount of water generated, you might consider infiltrating it within the LEED Project Boundary of the building fin which you are not using any of it. Please also remember that 100% treatment entitles you to an exemplary performanceIn LEED, certain credits have established thresholds beyond basic credit achievement. Meeting these thresholds can earn additional points through Innovation in Design (ID) or Innovation in Operations (IO) points. As a general rule of thumb, ID credits for exemplary performance are awarded for doubling the credit requirements and/or achieving the next incremental percentage threshold. However, this rule varies on a case by case basis, so check the credit requirements. credit that you may use as an ID credit.

I hope that helps, but if you have any further questions or concerns, please feel free to use the contact form at http://www.gbci.org/contactus and select "Follow up to GBCI Response," inputting your case number from this email's subject line.

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Natalie Tan
Mar 02 2013
Guest
176 Thumbs Up

groundwell non potable saline water

We are trying to pursue this credit, by using municipal 'brackish' water for irrigation and toilet flushing. The source of the municipal brackish water is groundwater pumped up from wells that is non-potable that is used throughout the region for irrigation. What is the definition for "municipal wastewater"? Can someone please advise if this will be accepted as wec2 and wec1 credit?
In addition, our engineer says a polishing plant would be required before this water can be used for toilet flushing. Any advice on this?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Mar 06 2013 LEEDuser Moderator

Natalie, according the LEED requirements, this is explicitly not allowed. However, there is a case to be made that it should be, but you'd probably need an official ruling via CIRCredit Interpretation Ruling. Used by design team members experiencing difficulties in the application of a LEED prerequisite or credit to a project. Typically, difficulties arise when specific issues are not directly addressed by LEED information/guide or LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org..

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E H Sustainability Architect
Feb 18 2013
LEEDuser Member
2300 Thumbs Up

Rainwater Harvesting Calculator

Does anybody know of a good rainwater harvesting calculator online anywhere? Most of the ones I have found do not let you adjust enough of the inputs to be useful.

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Courtney Royal, LEED AP BD+C Sr. Sustainability Consultant Taitem Engineering
Aug 02 2012
LEEDuser Member
706 Thumbs Up

Changes to system after project has been certified, what to do?

What is your experience with LEED projects that remove a specific technology (project did earn a LEED point) due to another recommendation, say a third party energy audit after the project was already LEED certified?

For example, a third party is benchmarking a LEED platinum project in update New York that captures stormwater runoff from the roof, collects the water in a big tank, and uses it to flush the toilets. Before the water is used to flush the toilets, it runs through a water purification systems that includes both filtration and UV (WEc2- Option 2, treat on-site wastewater to tertiary standards). The third party energy auditor would like to recommend unplugging the purification system in order to save energy (ECMEnergy conservation measures are installations or modifications of equipment or systems intended to reduce energy use and costs. in report). My question is, how would this affect their LEED credit? or would it? - the project was certified in 2010. I am a little confused. Thanks!

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Dylan Connelly Mechanical Engineer, Integral Group Aug 02 2012 LEEDuser Expert 6130 Thumbs Up

Courtney,
If your project is collecting rainwater and using it to flush the toilets then your project probably did or should have gone with WEc2 Option 1 - reduce potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. use for sewage conveyance by 50% through the use of nonpotable waterNonpotable water: does not meet EPA's drinking water quality standards and is not approved for human consumption by the state or local authorities having jurisdiction. Water that is unsafe or unpalatable to drink because it contains pollutants, contaminants, minerals, or infective agents. (e.g., captured rainwater). In which case if you remove the purification system it wouldn't affect your LEED credit intent.
In addition, if your project is already certified LEED NC, I've never heard of it being taken away regardless of what happens during occupancy.
Option 2 is if you are treating the water after it has been flushed (wastewater) and reusing it onsite.

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Courtney Royal, LEED AP BD+C Sr. Sustainability Consultant, Taitem Engineering Aug 02 2012 LEEDuser Member 706 Thumbs Up

Thanks a lot, Dylan. For some reason, every time I read this credit, I always get confused and automatically think Option 2 when captured rainwater is discussed. And then treating rainwater to tertiary standards seems way overkill!

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Diaa Madkour Architect
Jul 10 2012
Guest
469 Thumbs Up

Treated wastewater definition.

Hi,
working on an office building project, we r pursuing this credit through option 2 : "Treat 50% of wastewater on-site...etc."
Through the design Preliminary Review we received a comment stating that the wastewater should be generated from the flush fixtures not the lavatories as we did in the design.
My question is : Does anyone have an information (a definition in the reference guide) that state that the wastewater is water generated from flush fixtures only? because we have an intention to send a clarification stating that nothing in the guide state this. Please advise.

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Dylan Connelly Mechanical Engineer, Integral Group Aug 02 2012 LEEDuser Expert 6130 Thumbs Up

Water from lavatories and showers is considered wastewater by code definition. It is unlikely, however, in an office building that the lav and shower waste would add up to 50% of the total wastewater.
Here is a sentence from the ref guide "GraywaterGraywater is untreated household waste water which has not come into contact with toilet waste. Graywater typically includes used water from bathtubs, showers, bathroom wash basins, and water from clothes-washer and laundry tubs, though definitions may vary. Some states and local authorities also allow kitchen sink wastewater to be included in graywater. Project teams should comply with the graywater definition established by the authority having jurisdiction in the project area. systems reuse the wastewater collected from sinks, showers, and other sources for flushing toilets..."

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sompoche sirichote
Mar 28 2012
LEEDuser Member
170 Thumbs Up

Waste Water Calculation for Option 2

LEED template use the flush fixture water which calculated based on occupant usage. But our plumbing design is based on fixture unit which includes both flush and flow fixture into the WWTP sizing.
Our plumbing engineer comes up with the annual waste water of 19,000 kgal but the annual flush fixture water from LEED template is only 600 kgal. How can we fill in the LEED template?
Actually, all waste water will be treated by the WWTP and reused on site. We should achieve LEED credit requirement, shouldn't we?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Apr 06 2012 LEEDuser Moderator

Sompoche, you should be able to earn the credit with that system, provided you meet the specific detailed credit requirements.

I don't know how your plumbing engineer and the LEED template are so far off from each other. Have you looked at the differences of what they are assuming? You should fill in the LEED template based on the LEED protocols, even if that's different from your engineering figure, but I would closely look to make sure something isn't missing.

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Nadia Ayala Architect / LEED AP BD+C KILTIK Consultoría
Mar 22 2012
Guest
978 Thumbs Up

Should I consider process water?

Hi,
My project is a pharmaceutical facility. For their industrial process, they use a fairly large amount of water. I was wondering if process waterProcess water is used for industrial processes and building systems such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dishwashing, clothes washing, and ice making. is considered for this credit.

Our intent is to use some of this water on flush fixtures and irrigation. The spare amount would be conducted to a large soakaway pit.

Would that comply with WEc2 and WEc3 (assuming we have a 50% efficiency in fixtures, considering the use of process water)?

Thank you.

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Dylan Connelly Mechanical Engineer, Integral Group Mar 22 2012 LEEDuser Expert 6130 Thumbs Up

If the process waterProcess water is used for industrial processes and building systems such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dishwashing, clothes washing, and ice making. has been used and recaptured then it would be considered non-potable. Then you would be meeting the requirements of Option 1: Potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems. reduction.

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Nadia Ayala Architect / LEED AP BD+C, KILTIK Consultoría Mar 23 2012 Guest 978 Thumbs Up

Dylan,

Thank you for your reply. Nevertheless, I would still like to know, if we would pursue option 2 for this credit, would we have to consider the whole amount of water to achieve the 50% reduction, including the process waterProcess water is used for industrial processes and building systems such as cooling towers, boilers, and chillers. It can also refer to water used in operational processes, such as dishwashing, clothes washing, and ice making.? Thank you.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Feb 07 2013 LEEDuser Moderator

Nadia, I see why the question comes up, but the scope for wastewater under Option 2 here is identical to the scope of WEp1/c3. This is spelled out in places like LEED InterpretationLEED Interpretations are official answers to technical inquiries about implementing LEED on a project. They help people understand how their projects can meet LEED requirements and provide clarity on existing options. LEED Interpretations are to be used by any project certifying under an applicable rating system. All project teams are required to adhere to all LEED Interpretations posted before their registration date. This also applies to other addenda. Adherence to rulings posted after a project registers is optional, but strongly encouraged. LEED Interpretations are published in a searchable database at usgbc.org. #5186 made on 02/10/2009.

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Rudolph Schaar
Oct 21 2011
LEEDuser Member
112 Thumbs Up

Determining the number of full time equivalent (FTE) occupants

To determine the demand for water, what number should be used for FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. occupants - the number of occupants that the building is being designed for, or the maximum number of occupants calculated using SF/person units for egress code compliance?

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Emily Catacchio Sustainability Specialist, Wight and Company Oct 23 2011 Guest 6832 Thumbs Up

Hi Rudolph,

Above it states: "The calculations for wastewater use are based on the number of full-time equivalent (FTE) occupants. FTE calculations can sometimes be confusing in certain building types or occupancy types—see WEp1 for more information. "

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Oct 26 2011 LEEDuser Moderator

Rudolph, FTEFull-time equivalent (FTE) represents a regular building occupant who spends 8 hours a day (40 hours a week) in the project building. Part-time or overtime occupants have FTE values based on their hours per day divided by 8 (or hours per week divided by 40). Transient Occupants can be reported as either daily totals or as part of the FTE. Residential occupancy should be estimated based on the number and size of units. Core and Shell projects should refer to the default occupancy table in the Reference Guide appendix. All occupant assumptions must be consistent across all credits in all categories. should be the intended number for the project building. I would keep this number grounded in the reality of the project—not a theoretical code-based number. If the FTE number is not known for the project (as in CS), there are default numbers to use, from the LEED Reference Guide.

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E H Sustainability Architect
Jul 05 2011
LEEDuser Member
2300 Thumbs Up

Rainwater Harvesting Tank Calculations

Has anyone found a good spreadsheet/website that calculates the approximate size of a rainwater tank needed for a given roof areaRoof area is the area of the uppermost surface of the building which covers enclosed Gross Floor Area, as measured when projected onto a flat, horizontal surface (i.e. as seen in Roof Plan view). ‘Roofs’, or portions of roofs, covering unenclosed areas (e.g. roofs over porches and open covered parking structures) are not included in the areas used to evaluate compliance with SSc7.2, though they may be applicable to SSc7.1. and water usage? I have made my own but am unsure of how accurate it is. Does anyone know how detailed the supporting documentation needs to be for this credit? I am going on average rainfall per month and 80% efficiency. The project is located in Ireland.

Thanks so much.

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 19 2011 LEEDuser Moderator

S W, did you ever find any useful resources? Was your documentation approved?

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B Ballinger Apr 10 2012 LEEDuser Member 101 Thumbs Up

There are some interesting rainwater harvesting simulation graphs available at www.architectscience.com that show the basic relationship between tank size, daily use and the quantity of rainwater harvested over a twenty year period in Washington DC, Philadelphia and New York City. Ideally, rainwater tanks should be sized according to a simulation based on long term historical rainfall data of the project location.

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B Ballinger Apr 17 2012 LEEDuser Member 101 Thumbs Up

Also available from Virginia Stormwater BMPBest Management Practice Clearinghouse is a non-proprietary Excel spreadsheet that uses a 30 year rainfall database to generate tables and graphs indicating the quantity of harvested rainwater (developed by Rainwater Management Solutions). http://vwrrc.vt.edu/SWC/nonproprietarybmps.html

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Razan Nejem Environmental Engineer, LEED AP BD+C
Jun 15 2011
Guest
283 Thumbs Up

onsite waste water treatment plant

if our building is part of a bigger development which has a central waste water treatment plant does this count as being an onsite plant and will it count towards option 2.reducing 50% of building sewage conveyance?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Oct 27 2011 LEEDuser Moderator

Razan, I would review the LEED Minimum Program Requirements supplemental guidance document for some perspective on this question. There are cases (like with parking) where something can contribute to a credit without being in the LEED boundary. I would consider this a good possibility in your situation.

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Nadia Ayala Architect / LEED AP BD+C, KILTIK Consultoría Mar 22 2012 Guest 978 Thumbs Up

Hi Razan! We had the same case in a project. They awarded us WEc2 but not WEc3. They said that all water coming from this treatment plant (in a university campus, in which our building was located) counted as "municipally treated", not "on-site" and would qualify only to earn WEc2. Hope it helps.

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Dario Ibarguengoitia Ambiente Regenerativo Integral Nov 26 2012 LEEDuser Member 534 Thumbs Up

Hello, I have the same question. My project is located at an industrial park and they have a Central treatment water plant outside of my LEED boundary and the water is for the all the irrigation areas in the park. Does this count for the credit?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Nov 26 2012 LEEDuser Moderator

Dario, as I mentioned earlier, please review the MPRs, especially MPR3. There is a relevant exception in MPR3, and while I don't know if it has been applied in this type of situation, it seems like it should work.

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Melissa Merryweather Director, Green Consult-Asia Nov 27 2012 LEEDuser Member 1711 Thumbs Up

For our factory project, We DID have an exterior treatment plant, but it was on adjacent land owned by the same owner. So--between Nadia's answer and mine you can see what is allowable and not allowable for this credit. Please note: for our credit compliance, we had to show in detailed calculations that the capacity of the treatment plant was enough for all recycled water needs,AND that the INPUT to the system from our project was sufficient for the OUTPUT requirements (so it was calculated as if it was a stand-alone treatment plant).

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Karen Stewart President, LEED AP EcoPotential
Feb 25 2011
LEEDuser Member
600 Thumbs Up

Using well water for WEc2

Our MEP has recommended drilling a well and using local well water to flush the tolleits instead of using municipally supplied potable waterPotable water meets or exceeds EPA's drinking water quality standards and is approved for human consumption by the state or local authorities having jurisdiction; it may be supplied from wells or municipal water systems.. Based on the intent of this credit, I am not sure that using well water is a viable strategy. What is your opinion on this strategy?

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Tristan Roberts LEED AP BD+C, Editorial Director – LEEDuser, BuildingGreen, Inc. Feb 25 2011 LEEDuser Moderator

Use of well water is specifically mentioned as non-compliant in the Reference Guide for WEc1. Although not specifically mentioned in the same way for WEc2, I don't see that it would be any different. Do you?

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Karen Stewart President, LEED AP, EcoPotential Feb 25 2011 LEEDuser Member 600 Thumbs Up

Tristan, I agree. If well water is non-compliant for WEc1, I would think that it is non-compliant for Wec2.

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