Since Congress mandated the low-flow toilet in 1992, Americans haven't exactly felt flush with confidence about their plumbing.
These days, the double flush -- or the "courtesy flush," as Jerry Seinfeld put it -- has become commonplace.
While many blame the requirement that toilets be limited to 1.6 gallons of water, it may not be so much a question of how much water they contain as how well they're designed.
The fact is low-flow toilets have saved huge amounts of water. The Environmental Protection Agency says, as do other studies, that the average family of four now uses 20,000 fewer gallons a year. That's enough to fill a small, backyard pool.
It's just that some toilets do it better than others.
At the National Association of Home Builders Research Center in Maryland, experts test a variety of materials and equipment, including insulation, water heaters, and -- you got it -- toilets, to see which ones to the job best.
CNN's Bruce Burkhardt looks at the new methods the National Association of Home Builders have come up with to test toilet flushing. (May 3)
Bob Hill heads up the lab where a new testing method has been developed -- it seems the old industry standard, flushing 100 small plastic balls, was just too easy.
Now they use a collection of small sponges, some of them weighted with nails so they will sink.
"Basically we flush a number of sponges and paper wads down the toilet," Hill said. "We do five different challenge levels."
Each toilet is flushed repeatedly, and researchers count up what went through and what stayed behind. The numbers then are crunched in a computer to come up with the "clog potential index."
Kohler, a company with a well-known name in bathroom products, is marketing one solution to improve toilet efficiency.
"We're trying to encourage consumers to bring electricity into the bathroom," said David Kohler of the Wisconsin-based Kohler Co.
He's not talking about electrically heated seats -- but electrically powered flushing.