Hi to all,

I am currently working on this credit compliance for a large landscape area with a majority of native and adaptive plants. In the region where the project is locate rainfall events are scarce, however a rainwater tank is being proposed so to obtain 1 point (50% reduction).
In the LEED reference guide I could not find any input regarding the calculation of the alternative water source, particularly the calculation of the rainwater tank for LEED credit compliance.
My questions are the following:
-In order to obtain 1 point part of the outdoor water use baseline reduction should be covered by the water tank, since currently our calculation indicates <50%. Since this reduction only applies to the peak month (LWR), should we considered the cumulative rainfall in the tank only for that month? Should we considered the tank is full at the beginning of the peak month or just as full as the landscape water requirements?
-Is it required to calculate the cumulative rainwater tank of the previous month, that is from January to July?
-How do we actually demonstrate the %reduction from the rainwater tank implementation?

Sorry for my vague formulations and thanks in advance.