Below are seven milestones in the history of the flush toilet and how water use has evolved, according to Richard Rossi, Business Development Manager at Niagara Conservation, which produces plumbing fixtures with the goal of conserving water.
- Pre-1980: Toilets use as much as 7 gallons per flush (GPF).
- 1980-1992: Average flush volume is reduced to 3.5 GPF, although some still use up to 5 GPF.
- Mid-to-late 1980s: Low-flow toilets and ultra-low-flow toilets, using 1.6 GPF, emerge. Some states adopt new water conservation standards.
- Late 1980s to Early 1990s: To create a low-flow toilet, a 3.5 GPF unit is fitted with a modified tank trim that reduces the flush volume by almost half.
- 1992-1994: EPAct ’92 mandates maximum water use for U.S.-made toilets of 1.6 GPF or less, with a voluntary flush rating of 250 grams (8.8 ounces) minimum.
- 2006-2007: The WaterSense program launches, issuing high-efficiency specifications for toilets. Tank-type toiles must be independently certified to use 1.28 GPF or less, and remove at least 350 grams (12.3 ounces) of solid waste per flush, illustrated as a pass/fail test.
- Current Day: More than 1,100 models of high-efficiency toilets (HETs) are currently on the market. HETs outperform their ultra-low-flow (1.6 GPF) predecessors, and the 3.5 GPF models of the 1980s.
This article has been updated and was originally published in April 2021.