Water consumption calculation - showerhead flow rate pressure

Hello, LEED Interpretation 829 (applicable to NC v2009 projects) outlines this guidance: "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." (It may be helpful to review the inquiry portion of this LEED Interpretation as well, as one of the questions posed was "What is the appropriate methodology for establishing the calculation baseline when the water pressure supply rate (psi) is substantially lower than the 80 psi outlined as the baseline flow rates under the Energy Policy Act of 1992?")