Large water utilities are required to test water sources monthly for the bacteria, but there is no mandatory treatment. Spread through human or animal fecal matter, the parasite can cause the disease giardiasis. The parasite can survive in water for one to three months, and symptoms of the disease, including diarrhea, fatigue and cramps, can persist for weeks or months. Although tests specifically for giardia are expensive, those that show the presence of coliform indicate the water is probably contaminated with giardia as well. Public water systems using surface water are required to disinfect water so that at least 99.9 percent of the parasites are killed.
Chlorination is effective in killing the parasite, as is boiling water.
A problem in water caused by old lead service lines or in-house plumbing in homes built more than 30 years ago, lead can also be found in soldered joints of copper pipes and in brass fixtures. For infants and young children, chronic exposure can cause brain damage, learning disabilities and hyperactivity. In adults, lead has been linked to kidney problems, high blood pressure, anemia and nerve damage. Flushing water lines by running faucets for a few minutes at the start of the day can significantly lower lead levels. Since lead dissolves more easily in hot water, use cold water for food preparation.