Pressure flow rates

When introducing the design flow rate values in the indoor water calculator for option 1 calculated water use, we should use the flow rate fixtures values associated to the actual facility pressure flow rate instead of baseline reference pressure values, isn´t it? If we introduce the manufacturer flow rate values at the baseline pressure (60 Psi for lavatory faucet or 80Psi for showerhead) that would result in greater water consumption than actual and usual lower pressure of 43 PSi or even 15 Psi!