Bush signed the Energy Policy Act. This law made 1.6 gallons per flush a mandatory federal maximum for new toilets. This law went into effect on January 1, 1994 for residential buildings and January 1, 1997 for commercial buildings. The first generation of low-flush toilets were simple modifications of traditional toilets. A valve would open and the water would passively flow into the bowl. The resulting water pressure was often inadequate to carry away waste. Improvements in design now make modern models not only more water-efficient but more effective than old models. In addition to tank-type toilets that "pull" waste down, there are also now pressure-assist models, which use water pressure to effectively "push" waste. See also Low-flow fixtures Dual flush toilet Sewer dosing unit Waterless urinal Residential water use in the US and Canada References Toilets Toilet types Water conservation Water conservation tools Sustainable products Bathrooms