The use of phosphates as an ingredient in washing powder has been banned in the United States since 1993. In 2010, local governments began banning the use of phosphates as ingredients in dishwasher soap as well.
Detergents enter the water systems after being used in dishwashers. This water travels to the water treatment plants but not all phosphates can be removed from the dirty water. The remaining phosphates enter the water supply in lakes, ponds and rivers. They promote algae growth, which in turn causes eutrophication, a condition where the water becomes starved of oxygen. This kills existing plants and animals that live in the water source.
As phosphates are not illegal to use as an ingredient in dish detergents, manufacturers may still use them for up to 24 per cent of a detergent's formula.
As of July 2010, the ban on phosphates in dish washing detergent is voluntary. States that have adopted this ban or are increasing their regulation of the sale of phosphate detergents include Illinois, Indiana, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Hampshire, Ohio, Oregon, Pennsylvania, Utah, Vermont, Virginia, Washington and Wisconsin.