But there’s more to toilet tech than meets the eye.
Cedar Knolls, N.J.-based Niagara Conservation’s Stealth toilet uses a passive “vacuum-assist” setup to flush using just 0.8 gallons — far less than the 1.28 gallons offered by Water Sense-certified models on store shelves around the country.
Environmental Building News’ Alex Wilson explains how it works:
After the toilet is flushed, water fills a special inner chamber that’s hidden inside the conventional-looking toilet tank. (In this respect, it is like a pressure-assist toilet–with its tank-within-a-tank that is filled from the bottom.) As this inner chamber fills, though, air at the top is pushed down through a special transfer tube into the trapway, essentially creating a large air bubble between water in the toilet bowl and water in the sanitary trap near the base of the toilet. This air bubble, which fills about 12 inches of the trapway, exerts a force on the water in the trapway, raising the water level in the toilet bowl to create a larger water spot (water surface area) than would be expected from a toilet using just 0.8 gallons per flush.
When the toilet is flushed, water exiting the inner chamber creates a vacuum–depressurizing the trapway. This depressurization creates a suction force that pulls water from the toilet bowl into the trapway. During the flush, the trapway is entirely filled with water, which cleans the fully glazed trapway.
The bottom line: with the Stealth, lots of waste can be removed using very little water.
For now, Niagara recommends the toilet only be installed in residential applications, since it conveys waste less far than toilets with a higher flush volume.
The Stealth is available starting at $315.