Further improvements in the technology to overcome concerns about the initial poor performance of early models have further cut the water use of toilets and while federal standards stagnate at 1.6 gallons per flush, certain states' standards toughened up to require that new toilets use no more than 1.28 gallons (4.8 litres) per flush, while working far better than older models.
The US Environmental Protection Agency's WaterSense program provides certification that toilets meet the goal of using less than 1.6 US gallons per flush.
The early low-flush toilets in the US often had a poor design that required more than one flush to rid the bowl of solid waste, resulting in limited water savings.
In response, US Congressman Joe Knollenberg from Michigan tried to get Congress to repeal the law[clarification needed] but was unsuccessful, and the industry worked to redesign and improve toilet functioning.
Some reduction in sewer flows have caused slight backups or required redesign of wastewater pipes, but overall, very substantial residential water savings have resulted from the change over time to more efficient toilets.