Toilets manufactured before 1980 for residential use typically used up to 5 gallons of water per flush, while those manufactured between 1980
and 1994 used up to 3.5 gallons. Federal water conservation standards have required toilets manufactured since 1994 to use no more than 1.6 gallons per flush.
Therefore, by replacing a 20- to 30-year-old toilet with one that now meets standard-efficiency requirements,
you could save up to almost 3,000 gallons of water per year for every person who regularly uses that toilet.
But a WaterSense-labeled high-efficiency toilet would save you even more—up to an additional 0.6 gallons per flush. (Toilets bearing the WaterSense label
use 1.28 gallons or less per flush.) This means that, depending on the technology style you choose (dual-flush, pressure-assist,
single-flush gravity, or flushometer valve), by replacing your old toilet with a WaterSense-labeled HE Toilet instead of a new standard-efficiency
(1.6 gallon-per-flush) model, you could save approximately 600 to 1,100 more gallons per year for every person who regularly uses that toilet.