Double Cyclone toilets from Toto use 1.28 gallons per flush while incorporating bowl-cleansing action: When the toilet is flushed, the primary nozzle fires a high-speed stream of water that scours the rim and starts the cyclone action. A second water nozzle then fires a high-speed stream; while a siphon jet harnesses the power of the water for waste removal. Toilets with this technology include Supreme II, Carolina II, Carlyle II, and Vespin II.
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