A dual-flush toilet uses a larger trapway and a wash-down water-powered mechanism instead of the air-powered siphoning technique used by traditional toilets. Dual-flush toilets offer two options: a button for liquid waste with less water, and a button for solid waste, which uses more water.
Dual-flush toilets use less water overall due to the wash-down mechanism. They use less than 0.5 gallons for the liquid waste option and about 1.6 gallons for the solid waste option.
Traditional toilets need a large amount of water to enter the bowl in order to operate the siphoning method of disposing of the waste. The larger trapway in a dual-flush toilet allows waste to exit the toilet bowl easier than in a traditional toilet and results in less clogging.