The innovation was supposed to save us water. But now, in shocking commode news, the water-saving organization Waterwise has revealed that dual-flush toilets actually waste water. Waterwise estimates that between 5% and 8% of U.K. toilets are leaking a total of 88 million gallons per day. Dual-flush toilets allow users to select from a small flush for liquids and a larger flush for solid waste, a design intended to save water.