Public Users of Public Water Supplies
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During a boil water advisory
General Procedures
Do not serve or consume:
- water that has not been disinfected,
- ice or drinks made with water that has not been disinfected, or
- raw foods rinsed with water that has not been disinfected.
Discontinue service of equipment with water line connections (e.g., water coolers, automatic ice makers, etc.).
Discard ice made prior to the boil water advisory issuance and discontinue making ice. Use commercially-manufactured ice.
Drinking Water
For drinking water, use:
- commercially-bottled water
- and/or water that has been disinfected for Cryptosporidium by:
- boiling at a rolling boil for 1 minute (at altitudes greater than 6,562 feet (>2,000 m), boil water for 3 minutes), or
- distilling
- and/or water hauled from an approved public water supply in a covered sanitized container
- and/or water from a licensed drinking water hauler truck.
Note: 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 onsite equipment for testing chemical residuals. Furthermore, 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 or #58 for either “cyst removal” or “cyst reduction.” (see A Guide to Water Filters for more information) 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.
Cooking and Food Preparation
For cooking and food preparation:
- Discard any ready-to-eat food prepared with water prior to the discovery of the water contamination.
- Prepare/cook ready-to-eat food using the drinking water alternatives listed above and/or restrict the menu to items that do not require water.
For cooking and food preparation equipment/utensils/tableware:
- Use single service/use articles.
and/or
Clean and sanitize equipment/utensils/tableware using the drinking water alternatives listed above. Follow the established procedures to wash, rinse, and sanitize. - Cryptosporidium on equipment/utensils/tableware may be disinfected using dishwashing machines that have a dry cycle or a final rinse that exceeds 113°F for 20 minutes or 122°F for 5 minutes or 162°F for 1 minute.
- Discontinue operations when inventories of clean equipment/utensils/tableware are exhausted.
Handwashing
For handwashing, wet hands with the drinking water alternatives listed above and apply liquid, bar, or powder soap.
- Rub hands together vigorously for 20 seconds, making sure to lather and scrub all surfaces, including backs of hands, wrists, between fingers, and under fingernails.
- Rinse hands well with running water – if running water is not available, water may be poured on the hands by another person.
- Dry hands with paper towels or an air dryer.
- Use the paper towels to turn off the faucet, if applicable.
Note: Cryptosporidium is not killed by alcohol gels and hand sanitizers. Soap and disinfected water are specifically recommended for preventing cryptosporidiosis.
When the boil water advisory is cancelled
- Flush pipes and faucets. Run cold water faucets continuously for at least 5 minutes.
- Flush water coolers. Run coolers with direct water connections for 5 minutes.
- Flush home automatic ice makers. Make three batches of ice cubes and discard all three batches.
- Run water softeners through a regeneration cycle.
- Drain and refill hot water heaters set below 113°F.
- Change all point-of-entry and point-of-use water filters, including those associated with equipment that uses water.
Note: This information supersedes the "Issuing and Rescinding a Boil Water Advisory" portion of the Cryptosporidium and Water Handbook.
Related Public Users of Public Water Supplies Links
Emergency Disinfection of Drinking Water
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Page last reviewed: April 16, 2008
Content Source: Division of Parasitic Diseases (DPD)
National Center for Zoonotic, Vector-Borne, and Enteric Diseases (ZVED)