Prev NEXT  


What if everybody in the United States flushed the toilet at the same time?

Low-flow Toilets: A Lot Less Mess

In Beijing, China a very low-flow toilet is demonstrated using only a half-gallon of water.
In Beijing, China a very low-flow toilet is demonstrated using only a half-gallon of water.
Courtesy China Photos/Getty Images

If everyone in Milwaukee conducted the same experiment from the first page using only low-flow toilets, only 528,934 gallons of wastewater would suddenly deluge the city's sewer system. This would still cause quite a mess, but it would correct itself much faster, and the water pressure would equalize more quickly, too.

But low-flow toilets weren't designed to save Milwaukee from a public health hazard and an environmental catastrophe. They were designed to conserve water. And they have become so valuable at serving this purpose that they have replaced traditional toilets in stores. In fact, it is federal law that no toilet may be produced in the United States that uses more than 1.6 gallons per flush.


When they were first introduced in the early 1990s, low-flow (or low-flush) toilets were accepted warily by consumers in the United States. They clogged easily, and even when the toilets didn't clog, they often failed to do their job on the first try. Some consumers griped that they had to flush the toilet more than once. If a homeowner had to flush a low-flow toilet three times, then he or she used 4.8 gallons, more than a gallon more than with a traditional toilet.

Some Americans became so fed up with low-flow toilets that they crossed the northern border into Canada to purchase 3.5-gallon toilets, since none were available for sale back in the States. But low-flow technology has improved since the '90s, and the next generation of low-flow toilets appears to combine improved function with water conservation.

The United States Environmental Protection Agency (EPA) suggests that consumers in the market for a toilet should look for the WaterSense label. This certification is given to toilets that use no more than 1.28 gallons per flush, verified by testing at independent laboratories.

The EPA estimates that the average American will flush the toilet around 140,000 times in his or her lifetime. Since the amount of available water has become a real issue in the United States in the past few years, low-flow toilets are helping to allay a growing problem. The EPA is not the only governmental agency encouraging Americans to replace their toilets with low-flow toilets: Some American municipalities are offering $50 and $100 rebates as incentives for homeowners to make the switch. If everyone in the United States used only WaterSense toilets, the country would save an estimated 900 million gallons of water per day, equal to roughly twenty minutes of flow over Niagara Falls [source: EPA].

Just the savings alone (around $90 per year on your water bill) is reason enough for many people. But don't forget to take into account that if everyone switched to WaterSense toilets, it would cut the amount of mess caused by everyone flushing their toilets at the same time by more than half. And avoiding ankle-deep sewage is good for everyone.

For more information on toilets and sewers, be sure to visit the next page.

Related HowStuffWorks Articles

More Great Links


  • Headlee, Celeste. "Can Low-Flow Toilets Gain Consumer Confidence?" NPR. August 8, 2007.
  • "2005 American Housing Survey for the United States." United States Census Bureau.
  • "How Wastewater Works…The Basics." United States Environmental Protection Agency. May 1998.
  • "Low-Consumption Toilet Operating System from Sloan Valve Company Helps K&B Retailers and Representatives Meet New Energy Act While Satisfying Today's Home Remodeling Market." Flushmate.
  • "Mortgage Related Statistics, Milwaukee, Wisconsin." NexTag. November 7, 2007.