Toxins in Tap Water: What You Should Know

Small Systems, Big Problems

pouring water into glass

If you pay a water bill, your house is linked up to a community water system. These utilities or companies typically collect water from a lake, a river, a reservoir, or an underground aquifer and then treat it -- through the use of filters and chemical disinfectants -- before shipping it back out to customers through a network of pipes. Under the 1974 Safe Drinking Water Act, these systems must regularly monitor water for contaminants and reduce them to safe levels determined by the EPA. They must also notify consumers quickly when there is a serious problem with water quality and must distribute an annual report on the water's source and quality. In 2009, 92 percent of people served by community systems received water with no violations above EPA limits.

Sounds good -- unless your family fell into that unlucky 8 percent. What are some clues that your own water system should be checked out? One is its source: "if your provider draws from a surface water source, like a lake or a river, you might have cause for more concern than if it draws from, say, an underground aquifer," says Sonya Lunder, Ph.D., an analyst from the EWG. Why? Surface water is more likely to have been exposed to human pollution and industry before it's treated, explains Dr. Lunder. That often causes providers to treat it more rigorously, which can lead to an excess of disinfection by-products in your water.

Also a red flag: your provider isn't serving many households. Almost all health-based violations occur at systems serving fewer than 10,000 people, and those serving fewer than 500 are especially at risk. Whereas larger water suppliers can usually afford highly trained staff and sophisticated equipment to meet government standards, small providers sometimes lack the resources to keep up with changing regulations.

Another sign of potential problems is if your water system is more than 100 years old -- and you never see or hear of crews replacing water mains, storage tanks, and other pieces of equipment. This may be especially important in regions with sandy soil, since the sand can erode the outside of the pipes that deliver water to your house. "Many water systems are passing the century mark, and infrastructure failure rates are rising, which can allow contaminants to seep into treated water," says Jeffrey K. Griffiths, M.D., chair of the EPA's Science Advisory Board's Drinking Water Committee.

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