A Boil Water Advisory (BWA) is a public health warning issued when drinking water is, or could be, contaminated with harmful microorganisms like bacteria, viruses, or parasites. Contamination may occur due to a water main break, a system pressure drop, or issues at the water treatment plant. Because these pathogens can cause serious gastrointestinal illness, the advisory means tap water is not safe for consumption without treatment. This guidance provides safety protocols for maintaining hygiene and managing water use until the advisory is officially lifted.
Handwashing Protocols During the Advisory
For general personal hygiene, vigorous handwashing with soap and unboiled tap water is often considered acceptable by public health officials. The combination of friction, soap, and a thorough 20-second scrub helps physically remove most contaminants from the skin’s surface.
The safest practice is to assume the tap water is contaminated, particularly when preparing food or caring for infants and the immunocompromised. The most effective alternative is to use an alcohol-based hand sanitizer containing at least 60% alcohol, which inactivates most germs. Hand sanitizer should be used if hands are not visibly soiled, or as a follow-up step after using tap water for general washing.
For activities requiring clean hands, such as washing a baby bottle or preparing a meal, the final rinse water should be boiled and cooled potable water. While soap removes contaminants, a final rinse with safe water prevents re-exposure to any remaining pathogens. This maximizes the destruction and removal of potential pathogens like Cryptosporidium and E. coli, which may be present in the untreated water supply.
Boiling and Storage Instructions for Potable Water
Making tap water safe for drinking, cooking, and critical hygiene involves a simple but precise thermal disinfection process. First, if the tap water appears cloudy or contains sediment, strain it through a clean cloth, paper towel, or coffee filter to remove particulate matter before boiling. This pre-filtration step ensures the heat can effectively reach and destroy microorganisms.
The water must be brought to a full, rolling boil, where bubbles vigorously rise from the bottom of the pot to the surface. At most altitudes, maintaining this rolling boil for a minimum of one minute is sufficient to kill disease-causing organisms. For people living at elevations above 6,500 feet, the boiling time must be extended to three minutes, as water boils at a lower temperature in thinner air.
After boiling, the water should be allowed to cool naturally before it is used or stored, preventing accidental burns. The safe, cooled water must then be poured into a clean container with a tight-fitting cover to prevent recontamination. Storing boiled water in the refrigerator in sanitized containers ensures a readily available supply for drinking and preparing food.
Safe Water Practices for Other Household Needs
Beyond handwashing, several other household activities require modifications to prevent exposure to contaminated water. For oral hygiene, untreated tap water must not be used for brushing teeth or rinsing the mouth. Only bottled or properly boiled and cooled water should be used for this purpose to prevent ingestion of pathogens.
For showering and bathing, healthy adults can generally use tap water, but care must be taken to avoid swallowing any water. Infants, young children, and people with open wounds or compromised immune systems should be given a sponge bath using pre-boiled and cooled water to eliminate the risk of accidental ingestion or contact with vulnerable areas.
Washing dishes by hand requires a sanitizing step, as the tap water is unsafe for the final rinse. After washing and rinsing dishes normally, they should be soaked for at least one minute in a solution made of one teaspoon of unscented household bleach mixed with one gallon of water. Alternatively, using a dishwasher is safe only if it has a sanitizing cycle or reaches a final rinse temperature of at least 150°F (66°C).
All food preparation, including washing produce, cooking, and making ice, must exclusively use bottled or boiled water. Similarly, pets should only be given water that has been boiled and cooled to protect them from the same waterborne illnesses that affect humans.
Clearing the System When the Advisory is Lifted
Once the advisory is lifted, several steps are necessary to transition back to normal water use. All plumbing must be flushed to remove any lingering contaminated water from the pipes. This process begins by running all cold water taps for at least five minutes to clear the lines.
The hot water system also requires flushing, accomplished by running the hot water tap for a longer duration, typically 15 minutes for a standard 40-gallon hot water tank. Any ice made during the advisory must be discarded, and the automatic ice maker should cycle and discard the first three batches of new ice.
Water-using appliances and filters require attention. Filters that came into contact with the potentially contaminated water should be replaced according to the manufacturer’s directions. This includes refrigerator filters, pitcher filters, and reverse osmosis cartridges. The dishwasher should also be run empty through one full cycle after the hot water lines have been cleared.