The current plumbing code requires toilets that use no more than 1.6 gallons per flush. This standard was adopted in 1992 (replacing the old limit of 3.5 gallons per flush) and has not changed in 15 years, even as water problems in the US are escalating. Responding to the growing concern over excessive water use in buildings, many companies have begun to offer even lower-flush toilets and urinals. Two good examples are dual-flush valves for tankless toilets (the kind you use in public places) and a dual-flush toilet with a 1.6 gallon flush for solid matter and a 0.8-gallon flush for liquid.
In January 2007 the US Environmental Protection Agency introduced a voluntary standard, with a 20% reduction in the 1992 levels, down to 1.28 gallons per flush. Manufacturers who meet this new standard can display the "Water Sense" logo on their products. One manufacturer estimated that a family of four could save 7,000 more gallons of water per year using adual-flush toilet.100
Australia is suffering through a multi-year drought, said to be the worst in 100 years. Water levels in reservoirs for major cities such as Sydney had fallen to less than 30% of capacity, and the federal government is preparing to spend more than $10 billion (Australian) on a water desalination plant for the city. Watering restrictions were in force everywhere, with watering of gardens only allowed once or twice a week during the summer.
Because of the drought, dual-flush toilets have been mandatory in all Australian new homes since 2003. North American homes would be well served with similar requirements, as we get used to more permanent drought conditions and water shortages in the West and Southwest, brought about by population growth and global warming.
One of the major manufacturers of dual-flush toilets is an Australian company, Caroma. Living in a LEED Gold-certified apartment in Portland in 2005 and 2006, I used a Caroma dual-flush toilet, and I can attest that it worked just fine. In addition, with a large button for a big flush and a small button for a small flush, even a kid can figure it out. In most homes, you'd never know the difference in performance between the two, but you'd save about 40% of the water you would normally use for flushing, figuring three liquid flushes for every solid flush.
If you ever wondered how toilets are evaluated and rated for water use, the testing labs use thousands of flushes to evaluate their performance characteristics. You may be surprised, and perhaps feel enlightened, to know that soybean paste has approximately the same specific gravity and consistency as fecal matter. In 2005 a Canadian testing operation was reported to have imported 18,000 pounds of "non-food-grade" soybean paste (aka miso) from Japan, because it had to simulate hundreds of flushes for each toilet tested.101 So, next time you drop into a local Japanese restaurant and are served miso soup, remember to smile.
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