Dual Flush Toilet Review: Washdown vs. Siphonic ActionBy
Professor Toilet is pleased to see enthusiasm for dual flush toilets finally catching on in the United States.
Designed more than 30 years ago by an Australian Toilet Scientist, dual flush technology can reduce water usage by up to 67%. To put this into perspective, that’s like saving an average of 9,600 gallons a day over the old 3.5-gallon behemoths, or enough water to fill three hot tubs each day when compared to a 1.6-gallon toilet.
Dual flush toilets are actually mandated in Australia and Singapore, and catching on fast in North America because of the simple premise: “push 1 for 1 and push 2 for 2,” A number 1 flush uses less water, a far more pleasant alternative to “if it’s yellow, let it mellow.” A number 2 flush is designed to take down solids without clogging, typically using the same 1.6 gallons per flush (gpf) as standard toilets like the Champion 4 and Cadet 3.
Dual Flush Washdown vs. Dual Flush Siphonic
One issue slowing more widespread adoption of dual flush toilets in the US is a technical term that toilet scientists call skid marks. The Professor assumes that you don’t need a visual on that; in short, it’s a bowl that won’t stay clean after pushing 2 for 2. You may use other words for it when it happens.
Dual flush toilets rely on the “push” of water to cleanse the bowl in what is known as a washdown flush. In contrast, standard toilets depend on the more popular siphonic action to “pull” waste out.
To strengthen the push action, the bowls of dual flush models are sloped more sharply than standard toilets to give the water greater momentum, which can also increase splashing. The steeped bowls mean a smaller “water spot” or water surface area in the bowl, which makes it more likely that toilet paper or other waste will cling to the sides of the bowl, staining and generating odors.
The toilet engineers at American Standard have overcome these two hurdles with a dual flush toilet that removes every last trace of paper and waste, as well as one that offers a large traditional water surface area.
The WaterSense-certified H2Option Dual Flush Toilet is the first truly siphonic dual flush toilet, which generates strong push and pull action through forceful but quiet jetted action under the rim. When the user flushes H2Option, some of the water is instantly diverted to the rim where there are a series of chambers. The air in the chambers pushes the ongoing coming water forcefully out into the bowl. The resulting downhill rush of water creates an all-but-irresistible pull on the water behind it, so that every last trace of waste is removed from the bowl.