Toilets are by far the biggest water guzzlers in most U.S. homes. According to the U.S. Geological Survey, toilets account for approximately 30 percent of indoor water usage at homes, sucking down about 25 to 30 gallons (95 to 114 liters) per day per person [source: U.S. Geological Survey]. That's the equivalent of about 10,000 gallons (37,800 liters) of water per person per year. But it's not all bad news: These days, homeowners are taking steps to conserve water, and tankless toilets can help with those efforts.
During the first half of the 20th century, toilets used at least 5 gallons (19 liters) of water per flush (gpf). Today, the U.S. Department of Energy requires that residential toilets use no more than 1.6 gpf (6 liters) [source: Department of Energy]. Toilet manufacturers are looking for ways to reduce flush volumes even further. The latest technology available on tankless systems allows for light flush modes of about 1 gallon per flush or less.
In the United States, federal law also addresses commercial tankless toilets (i.e., flushometers). The current standard specifies that flushometers use no more than 1.6 gpf, though many manufacturers are shooting for 0.8 gpf (3 liters) [source: Koeller]. Urinals are also improving: The U.S. Department of Energy's standards for urinals are currently at 1 gpf (3.8 liters) [source: Department of Energy].
An important water-saving feature of commercial flushometers is that they can be designed to let users push a handle in one direction for liquid waste and another direction for solid waste. The latter would trigger a full flush while the former would trigger a partial flush. This dual-flush technology is becoming common other parts of the developed world, including the U.K. and Australia, though it has yet to become as popular in the United States. With wider use of these features, water efficiency is expected to improve for all toilet types.
Learn lots more about toilets and water use by visiting the links on the next page.