We have seen several comments regarding the possibility (or not) to achieve both WEp1 and WEc3 through the use of on-site greywater and wastewater. We would like to confirm that, in fact, we can calculate the % of water savings by subtracting the on-site reuse of grey and wastewater for toilets and urinals, from the design annual water use as a result of the installed fixtures. A project we are working on cannot achieve a 20% reduction solely from fixtures, but is treating all of its grey and waterwater and reusing it, which means that potable water will only be used for faucets and showers, achieving a water savings of over 50%. The Additional Water Guidance (version 8) states that "projects are allowed to use on-site alternative sources of water to achieve water use reduction through an alternative compliance path". It goes on to say that "examples of on-site non-potable water sources that apply to the Water Use Reduction PREREQUISITE and credit include: greywater, captured rainwater, air conditioning condensate, etc". Because we have seen comments saying that the 20% reduction MUST be achieved through efficient fixtures, we would like to confirm that this is not the case and that, per the Additional Water Guidance, grey and wastewater reuse can in fact be used to achieve the 20% reduction.