Hi all,

For some background on our project:

- we have on-site rainwater capture as well as connection to a municipal non-potable water supply
- the municipal water is used to top up the rainwater storage tank in times of low rainfall (i.e. rainwater + municipal water are combined in the same tank)
- water from the tank is used to satisfy 100% of the building's flushing and irrigation demand (i.e. 100% from non-potable sources)

Our problem is:

- municipal non-potable water cannot contribute to WEp1 or WEc3 whereas it can count towards WEc1 and WEc2 (as per the USGBC water use additional guidance document)

- While we can estimate the proportion of rainwater that ends up as irrigation water or flushing water, the project does not receive any recognition of the rainwater used for irrigation as the municipal supply can satisfy the 100% non-potable irrigation requirement without rainwater.

My question is:

- As there is no net environmental difference, can the project elect to apportion captured rainwater to suit the project (i.e. 100% for flushing and 0% for irrigation)? This would ensure that the project gets full recognition for the rainwater facilities installed onsite, drastically simplify assumptions and arbitrary calculations and prevent the need to install two separate rainwater and municipal non-potable water tanks (pipes and fittings) just to achieve full points.

Any input from project with similar experiences would be most helpful.

If possible I would like to avoid having to submit a CIR!