Water use in a luxury hotel

Here is an NCv2.1 CIR Ruling that you might find helpful: http://www.usgbc.org/LEED/Credit/CIRDetails.aspx?CIID=829

Below is the key paragraph from the "ruling" part of the CIR. Note that this CIR is from an older LEED rating system, and was given in 2004, but it should be able to give you some general guidance on how GBCI is likely to view this issue."The underlying assumptions used for calculating projected water use savings should remain consistent between the baseline and design case. Supply water pressure varies across the United States and within individual buildings (as you note in your inquiry). Flow rates at 80 psi are used for the calculations in this credit for consistency and to reward use of efficient fixtures. It is recommended that all projects use the flow rates reported by the manufacturer at 80 psi for comparison with the Energy Policy Act of 1992 flow rates. If you wish to use on-site tests to report the most accurate volume of water use, you must be consistent throughout all fixtures and test both baseline and design fixtures. It is not acceptable to use flow rates at 80 psi for some fixtures and actual flow rates for other fixtures. Measurement can also be used to account for the benefits of whole-building strategies, e.g., flow restrictors at the water service entrance."