The drinking water that is supplied to our homes comes from either surface water or ground water. Surface water collects in streams, rivers, lakes, and reservoirs. Ground water is water located below the ground where it collects in pores and spaces within rocks and in underground aquifers. We obtain ground water by drilling wells and pumping it to the surface.

Public water systems provide treated water from surface and ground water for public use. Water treatment systems are either government or privately-held facilities that withdraw water from the source, treat it, and deliver it to our homes.

A private well uses ground water as its water source. Owners of private wells and other individual water systems are responsible for ensuring that their water is safe from contaminants. (Information from CDC)

A. The presence of certain contaminants in our water can lead to health issues, including gastrointestinal illness, reproductive problems, and neurological disorders. Infants, young children, pregnant women, the elderly, and immunocompromised persons may be especially at risk for becoming ill after drinking contaminated water. For example, elevated levels of lead can cause serious health problems, especially for pregnant women and young children. Federal law requires that systems reduce certain contaminants to set levels, in order to protect human health. However, the presence of contaminants when tested does not necessarily indicate that the water poses a health risk. (Information from CDC)

A. There can be many sources of contamination of our water systems. Here is a list of the most common sources of contaminants:

• Naturally occurring chemicals and minerals (for example, arsenic, radon, uranium)
• Local land use practices (fertilizers, pesticides, livestock, concentrated animal feeding operations)
• Manufacturing processes
• Sewer overflows
• Malfunctioning wastewater treatment systems (for example, nearby septic systems)

A. The United States has one of the safest public water supplies in the world. However, if you are concerned about contaminants in your home’s water system, contact your state drinking water certification officer to obtain a list of certified laboratories in your state. Depending on how many contaminants you wish to test for, a water test can cost from $15 to hundreds of dollars. The Safe Drinking Water can give you information on testing methods.

A. A change in your water's taste, color, or smell is not necessarily a health concern. However, a change could be a sign of serious contamination problems. If you notice a change in your water, call you public water system company. If you want to test your water, your local health department should assist in explaining any tests that you need for various contaminants. If your local health department is not able to help you can contact a state certified laboratory to perform the test. To find a state certified laboratory in your area call the Safe Drinking Water Hotline at (800) 426-4791.

A. In order to disinfect your drinking water during a boil water advisory, you should boil your water at a rolling boil for at least one minute (at altitudes greater than 6,562 feet (> 2000 meters), boil water for 3 minutes). Boiling your water for at least one minute at a rolling boil will inactivate all harmful bacteria, parasites, and viruses from drinking water.

Although chemicals (for example, bleach) are sometimes used for disinfecting small volumes of drinking water for household use, chemical disinfection is generally not recommended for commercial establishments because of the lack of on-site equipment for testing chemical residuals. Furthermore, the parasite, Cryptosporidium is poorly inactivated by chlorine or iodine disinfection. Cryptosporidium can be removed from water by filtering through a reverse osmosis filter, an "absolute one micron" filter, or a filter certified to remove Cryptosporidium under NSF International Standard #53 for either "cyst removal" or "cyst reduction." See "A Guide to Water Filters." However, unlike boiling or distilling, filtering as just described will not eliminate other potential disease-causing microorganisms, such as bacteria and viruses. Ultraviolet light treatment of water is not effective against Cryptosporidium at normally-used levels.