While older "water-saving" showerheads used to limit the flow to 2.5 gallons of water per minute, today's high performance water-saving showerheads use no more than 1.8 gallons of water per minute, yet still deliver a satisfying spray. With kitchen faucet aerators the flow need be no more than 1 to 1.5 gallons per minute, and the savings can be enhanced if the aerator includes an off-value (allowing for the temporary interruption of the flow). Because bathroom faucets are primarily used for washing hands, brushing teeth, and shaving, even less water is needed here, with today's water-saving bathroom faucet aerators able to allow a maximum flow of just 0.5 to 1.0 gallons per minute of water.

Once you know what the flow rates are of your existing fixtures, you'll be able to determing what the savings would be if you replaced them wth more efficient models.