Grey Water for Flushing

Yes, according to page 83 of the LEED-EBOM Reference Guide, graywater is an implementation option for this credit.

Yes, but until the last time I checked, the submittal form on LEEDonline did not accommidate this, so you can expect to submit additional information to support your claim.

we are looking at exactly the same issue and to account for this in the LEED online form, we are assigning a 0 value to the flush rate for the toilets and urinals, which use only graywater. I read somewhere that this is an acceptable way of approaching this, provided this claim is supplemented with additional information, which confirm this. Am I correct?

In LEED-NC, you have to submit greywater or rainwater reuse as an alternative compliance path—the calculator won't accommodate them. I would guess that this is the same in EBOM, and that jerry-rigging the calculator to make it do what you want will not be acceptable. But I am just guessing. Might be worth a note to GBCI via the "feedback" form.

thank you, Tristan. Have sent a message to LEED online and will provide feedback to LEEDUser, once clarified.

further to the discussion on accounting for graywater in WEP1 and WE2 I sent a query to LEED online. For the benefit of others, i have included below our query and the response from LEED online, which clarifies the matter:

Inquiry: around 50% of the total flush fixtures installed in the building use only non-potable reclaimed cooling tower water. Can we account for this by assigning a 0 value in the column "installed flush rate" or do we have to use an alternative compliance path?

Response: The current WE Prerequisite 1 form does not take into account the use of nonpotable water. To account for nonpotable water use, in addition to completing the tables with the occupancy, fixture, and fitting data, please use the Alternative Compliance path section of the forms (WEp1 and WEc3 if applicable) to provide additional documentation/calculations to support the additional savings claimed from non-potable water use (including but not limited to system capacity to show that the nonpotable water is sufficient to meet demand and the final water use savings percentage). By using the Alternative Compliance path section, the points documented indicated on the form will update according to the number of attempted points.

I know this thread is old and addresses LEED 2009 but I wanted to know if anyone had any information on how to calculate this credit with LEED v4.

Hi Michael, sorry for the late reply. You may have finished investigating this, but in EBOM v4 the water prerequisite deals only with the efficiency of fixtures - you aren't allowed to apply nonpotable water use to the prerequisite. However, you can do so under the corresponding credit. This is noted in the "Behind the Intent" and "Changes from LEED 2009" sections of the Reference Guide for WEp1: Indoor Water Use Reduction. Unfortunately I don't see how to actually do that using USGBC's calculator or credit form. So in theory that's how USGBC wants you to approach nonpotable water in v4, but they haven't made it particularly easy to execute.