Press Advisory

CDC - Centers For Disease Control and Prevention
Office of Public Affairs, CDC (404) 639-3285

CDC, EPA Issue Drinking water Guidance For People with Weakened Immune Systems

The Centers for Disease Control and Prevention (CDC) and the Environmental Protection Agency (EPA) today issued guidance to people with severely weakened immune systems who may want to take extra precautions to reduce the risk of infection with cryptosporidium from drinking water. These extra precautions include talking to a health-care provider about boiling drinking water, or using certain drinking water filters, or using certain bottled waters.

Cryptosporidium is a parasite commonly found in rivers and lakes, especially when the water is contaminated with sewage or animal waste. When the parasite makes its way into drinking water supplies, it can cause severe outbreaks of gastrointestinal illness including diarrhea, nausea, and/or stomach cramps. For the vast majority of Americans, Cryptosporidium does not pose a grave danger, and the CDC-EPA guidance does not apply to them. However, the guidance does pertain to people with HIV-AIDS, cancer and transplant patients taking immunosuppressive drugs, and people with genetically weakened immune systems.

The CDC-EPA guidance suggests that immunosuppressed individuals discuss their risks with their health-care provider. Those who wish to take extra precautions to avoid waterborne cryptosporidiosis can bring their drinking water to a rolling boil for 1 minute. Boiling water is the most effective approach for killing cryptosporidium.

As an alternate to boiling water, people may use the following measures:

A point-of-use (personal use, end of tap, under sink) filter. Only point of use filters that remove particles one micrometer or less in diameter should be considered. Among the most effective point-of-use filters are those labeled reverse osmosis or "Absolute" one micron filters or those certified by National Sanitation Foundation International under Standard 53 for "Cyst Removal." The "Nominal" one micron filter may not reliably remove Cryptosporidium.

Bottled water. Many, but not all, brands of bottled water may provide a reasonable alternative to boiling tap water. However, the origin of the source water, the types of microorganisms in that water, and the treatment of that water before it is bottled varies considerably. Bottled waters derived from protected well and protected spring water sources are less likely to be contaminated by cryptosporidium. Bottled water containing municipal drinking water derived from rivers and lakes are more likely to be contaminated. Any bottled water treated by distillation or reverse osmosis before bottling assures Cryptosporidium removal.

Neither EPA nor CDC maintains a list of point-of-use filters or bottled water brands that meet the above criteria. NSF International can provide a list of filters that meet NSF criteria. The NSF address is 3475 Plymouth Road, PO Box 130140, Ann Arbor, Michigan, 48113-0140; telephone 800-NSF-8010. Individuals who contact bottlers or filter manufacturers for more information should request data supporting claims that their brand of bottled water or filter can meet the above criteria. For more information on bottled water contact the International Bottled Water Association's Hotline at 1-800-water-11

CDC and EPA will continue to assess the risks of waterborne cryptosporidiosis and will report new information as it is developed. Individuals concerned about the threat of cryptosporidiosis in tap water can call CDC's National AIDS Hotline @ 1-800-342-AIDS.


June 15, 1995 Centers for Disease Control and Prevention

The Foregoing Was Released by CDC on the Indicated Date