A Boil Water Advisory (BWA) is a public health safeguard issued by local water authorities when the drinking water supply may be compromised. This notice informs the public that the tap water is potentially contaminated with disease-causing microorganisms, such as bacteria, viruses, or parasites. Following the advisory’s instructions is necessary to prevent waterborne illnesses.
Defining the Advisory and Its Causes
A Boil Water Advisory communicates a potential risk of microbiological contamination within the public water system, meaning pathogens like E. coli, Giardia, or Cryptosporidium may be present. These advisories are typically issued as a precaution, rather than a confirmation, to protect consumers while water quality is verified. The advisory is a temporary measure until the system is repaired and testing confirms the water’s safety.
One common trigger for an advisory is a sudden loss of water pressure, often falling below 20 pounds per square inch (PSI). Low pressure can create a vacuum, allowing untreated groundwater or other contaminants to be pulled into the distribution pipes through cracks or leaks. Physical infrastructure failures, such as water main breaks, power outages at treatment plants, or major flooding, also frequently necessitate an advisory. In some cases, a mandatory notice is issued after positive test results confirm the actual presence of a contaminant.
Essential Steps for Preparing Water
The most reliable way to neutralize potential pathogens is by boiling the water, as the high temperature effectively kills bacteria, viruses, and protozoa. To properly prepare water, first bring it to a full, rolling boil where bubbles rapidly rise from the bottom of the pot. The water should be allowed to boil vigorously for at least one full minute to ensure disinfection.
Individuals residing at elevations above 6,500 feet should extend the boiling time to three minutes because water boils at a lower temperature at higher altitudes. If the tap water appears cloudy or turbid, it should first be strained through a clean cloth or coffee filter to remove sediment before boiling. After boiling, the water must be allowed to cool completely before it is transferred into a clean, covered container for storage.
Water Use Restrictions During the Advisory
During an advisory, all water intended for consumption or internal contact must either be boiled or sourced from sealed bottled water. This includes drinking, making ice, preparing food, washing raw fruits and vegetables, and mixing baby formula. Even seemingly minor activities, like brushing teeth, should be done with cooled, boiled water or bottled water. Old ice made from tap water during the period of concern must be discarded, as freezing does not destroy these pathogens.
Showering and bathing are generally considered safe for adults, provided care is taken to avoid swallowing any water. However, special caution is advised for infants and young children, who should be given sponge baths to prevent accidental ingestion of the water. For washing dishes, a home dishwasher is safe only if it has a sanitizing cycle that reaches a final rinse temperature of at least 150°F. If handwashing, dishes should be rinsed in a separate basin using a sanitizing solution, such as one teaspoon of unscented household bleach per gallon of warm water, followed by air drying.
Water for household pets should also be replaced with boiled and cooled water or bottled water. Activities that do not involve internal consumption, such as doing laundry, are safe to continue using tap water.
How Authorities Lift the Advisory
The advisory remains in effect until the water utility confirms that the water quality meets all public health standards. This confirmation requires a series of satisfactory microbiological test results from multiple water samples collected across the affected area. These test results must show the absence of contamination over two consecutive sampling periods, which often takes 24 hours between tests.
Once the advisory is officially lifted, residents must flush their household plumbing to remove any potentially remaining untreated water. This involves running all cold water faucets for a minimum of one minute. Hot water lines and appliances that use water, such as dishwashers and automatic ice makers, also need flushing. Any water filters, including those in refrigerators and pitchers, should be replaced to avoid reintroducing contaminants into the newly safe water supply.