The biggest myth about tap water is that it is clean, even in countries with historically reliable systems, according to Water Quality Scientist Dr. Eric Roy. The source of contamination could also be inside the house, especially in older homes with lead pipes or asbestos. The easiest way to determine what's in your water is to review the annual water quality report from your local water utility. Home test kits can test for lead, bacteria, and excess chlorine. While municipal water treatment systems are effective at removing many contaminants, certain pollutants can still make it through the treatment process. The most common source of bacterial contamination is an accidental sewage overflow. The EPA has suggested several ways to reduce lead contamination: Purchase a water filter certified for lead removal, or drink only cold water, and flush your pipes before drinking water if it has been stagnant for an extended period.