The advantages of a dual flush toilet versus a conventional toilet can be summed up concisely: Environmental impact, cost savings and upkeep.
Environmental Impact. Dual flush toilets bear their namesake because of the two (dual) setting mechanism that drives their operation. This two setting mechanism is usually a button or a lever on the toilet that allows you to flush either a low volume flush or a high volume flush. Low volume flushes are designed for liquid waste, while high volume flushes are designed for solid waste. Unlike standard toilets designed with only one flushing option, the low volume flush of dual flush toilets allows for the conservation of water when using the liquid waste setting. As such, dual flush toilets are high efficiency toilets (HET) and are in compliance with the National Energy Policy Act of 1994, using no more than 1.6 gallons per flush (gpf) compared to older toilet models that use as much as 3.5 to 5 gpf. Lower volume flushes on new dual flush toilets do not use more than 1.1 gpf.
Cost Savings. A dual flush toilet drives lower water usage in your home, thereby saving money on your monthly water bill. The Environmental Protection Agency (EPA) estimates that 4,000 gallons of water can be saved annually in a residential household that employs dual flush toilets.
Low Upkeep. Older, “one flush” toilets simply use a pressure siphoning system to dispose of waste. Dual flush toilets are generally designed to utilize gravity to dispose of waste down a large trapway. This design typically cuts down on clogging and saves you the headache of an undesirable plunging expedition.