By the Care2 staff.
There are almost 170,000 public water systems in the United States. Water utilities treat nearly 34 billion gallons of water every day.
When shopping for a water purifier, it’s important to first research what your municipal water problems are. Different communities will have different contaminants in their water supply, and you want to get a water purifier that solves your specific water problems.
Water Authorities are required under the Safe Drinking Water Act to provide a Consumer Confidence Report to consumers annually. The report allows consumers to know the quality of their drinking water, the contaminants in it, and the possible harmful effects. The report also allows consumers to decide whether or not a home water purifier is needed to make the water potable. Well water is not regulated.
The following US EPA link will allow you to get a copy of annual drinking water reports for your city.
However, not all contaminants are tested. In 2005, the nonprofit Environmental Working Group (EWG) tested municipal water in 42 states and detected some 260 contaminants in public water supplies. Of those, 141 were unregulated chemicals for which public health officials have no safety standards, much less methods for removing them.
Another 119 regulated chemicals—a total of 260 contaminants altogether—were found by the environmental group in a two-and-a-half-year analysis of more than 22 million tap water quality tests. The tests, which are required under the federal Safe Drinking Water Act, were conducted at nearly 40,000 utilities that supply water to 231 million people.
According EWG, the top 10 states with the most contaminants in their drinking water were California, Wisconsin, Arizona, Florida, North Carolina, Texas, New York, Nevada, Pennsylvania and Illinois—in that order. EWG said the biggest sources of contaminants were agriculture, industry and pollution from sprawl and urban runoff.
To find out which brands of filters remove which impurities, see this water filter comparisons chart.