Hi,

My project is located on a LEED certificated building. The building uses rain water to supply for irrigation and toilet flushing. How can I calculate the annual non-potable water supply to toilet flushing for only my project?
Can I estimate by equation 1:
Annual non-potable water supply for only my project = (Total Annual non-potable water supply of the building/Building area)*Project area ?

or equation 2:

Annual non-potable water supply for only my project = (Total Annual non-potable water supply for toilet flushing of the building/Building area)*Project area ?
or other equation ?