Public Water Systems FAQ

Frequently Asked Questions

Where does my drinking water come from?

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. For more information on private wells and individual water systems, visit CDC's Healthy Water Private Wells page.

What type of health issues can be related to water quality?

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.

How do I know that the water in my home is safe to drink?

The United States Environmental Protection Agency (EPA) is responsible for making sure that public water supplies within the United States are safe. In 1974, Congress passed the Safe Drinking Water Act. This law sought to protect the nation’s public drinking water supply by giving EPA authority to set the standards for drinking water quality and oversee the states, localities, and water suppliers who implement those standards. In 1986 and 1996, the law was amended to protect drinking water and its sources, which include rivers, lakes, reservoirs, springs, and ground water wells.

What contaminants should I be concerned about in my drinking water?

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 (e.g., arsenic, radon, uranium)
• Local land use practices (fertilizers, pesticides, livestock, concentrated animal feeding operations)
• Manufacturing processes
• Sewer overflows
• Malfunctioning wastewater treatment systems (e.g., nearby septic systems)

Who do I need to contact to find out more information about water quality in my area?

Drinking water quality varies from place to place.

Every community water supplier must provide an annual report, sometimes called a Consumer Confidence Report, or "CCR," to its customers. The report provides information on your local drinking water quality, including the water's source, contaminants found in the water, and how consumers can get involved in protecting drinking water.

• View the CDC's guide to Understanding Consumer Confidence Reports
• See if your CCR is posted online (U.S. Environmental Protection Agency Local Drinking Water Information)

How often does our public water system test our drinking water?

Drinking water can be tested around the clock, including hourly, monthly, quarterly, and annually, depending on the location and size of the public water system. Certain contaminants are tested for more frequently than others, as set forth by the Safe Drinking Water Act. Compliance testing is conducted once a year, before Consumer Confidence Reports (CCR) are mailed to consumers.

Every community water supplier must provide an annual report, sometimes called a Consumer Confidence Report, or "CCR," to its customers. The report provides information on your local drinking water quality, including the water's source, contaminants found in the water, and how consumers can get involved in protecting drinking water.

• View the CDC's guide to Understanding Consumer Confidence Reports
• See if your CCR is posted online (U.S. Environmental Protection Agency Local Drinking Water Information)

What common contaminants are included in this testing?

The EPA sets standards and regulations for the presence and amount of over 90 different contaminants in public drinking water, including E.coli, Salmonella, and Cryptosporidium species. More information regarding the specific contaminants and maximum contaminant levels can be found on the EPA’s website (Drinking Water Contaminant Candidate List and Regulatory Determinations).

What should I do if I want my household water tested?

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 Hotline can give you information on testing methods.

Who should I contact if my water has a funny smell, taste, or appearance?

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 or visit the State Certified Drinking Water Laboratories list.

How can I find out if there has been a violation in our public water standard?

When water quality standards have not been met, your public water system must notify you through the media (television or radio), mail, or other means. Your annual Consumer Confidence Report (CCR) is another way to find out about the water quality in your area. It provides information regarding contaminants, possible health effects, and the water’s source.

How do I find out if there is a boil water or other water advisory in my community?

There are three levels of public notification, based on the seriousness of a contamination event. A Tier 1 notification pertains to the most serious and acute contamination events. Notification must be broadcast by local media within 24 hours. Tier 2 allows for a 30-day notification. Tier 3 provides notification through the annual Consumer Confidence Report (CCR). Your public water system is responsible for notifying residents if the water quality does not meet EPA or state standards or if there is a waterborne disease emergency. Depending on which tier level applies, you should be notified by the media (TV, radio), mail, or other means. For more information, see CDC's boil water advisories page.

If there is a boil water advisory in my community, how do I disinfect my drinking water?

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 (e.g., 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.