A boil water advisory is a public health warning issued by local authorities when a community’s drinking water quality is compromised, often due to events like a water main break, system pressure drop, or contamination from flooding. This directive signals that the water may contain harmful microorganisms. The advisory is a necessary precaution to prevent waterborne illnesses, ensuring that water used for consumption is safe while the underlying issue is resolved and the system is tested.
The Specific Boiling Procedure
The procedure for treating tap water involves bringing the water to a rolling boil, where the water is bubbling continuously. At elevations near sea level, the Centers for Disease Control and Prevention recommends maintaining this rolling boil for a minimum of one full minute to ensure water safety. After the one-minute duration, remove the heat source and allow the water to cool naturally before being used or stored.
A longer boiling time is required at higher altitudes because water boils at a lower temperature. At elevations exceeding 6,500 feet (approximately 2,000 meters), the required boiling period is extended to three minutes. Once the water has cooled, it should be transferred to clean, covered containers with tight-fitting lids to prevent recontamination. This treated water is the only safe alternative to bottled water for all ingestion purposes during the advisory period.
Why Boiling Eliminates Health Risks
Boiling water is an effective method of pasteurization, which works by using heat to inactivate or destroy common waterborne pathogens. The high temperature targets the molecular structure of these organisms, including bacteria, viruses, and protozoa. This heat disrupts the cell’s ability to survive and replicate.
The process is highly effective against major contaminants like E. coli bacteria, norovirus, and the resilient cysts of protozoa such as Giardia and Cryptosporidium. Boiling addresses biological contamination, not chemical hazards. If the advisory is issued due to a chemical spill or heavy metal contamination, boiling the water will not make it safe and may even concentrate the chemical contaminants as the water evaporates.
Essential Uses for Treated Water
All water intended for consumption or contact with the mouth must first be boiled and cooled. This includes drinking, mixing beverages (such as infant formula), and preparing food. Ice made from untreated water must be discarded, and new ice must be made using only pre-boiled water. Treated water is also necessary for washing fruits and vegetables that will be eaten raw, and for cooking processes where the water is not brought to a sufficient boil.
For personal hygiene, brushing teeth requires the use of boiled or bottled water. While showering and bathing are generally safe for healthy adults, avoid swallowing the water; sponge baths are recommended for infants and small children. When handwashing dishes, a final sanitizing step is necessary: soak the washed items for at least one minute in a solution containing one teaspoon of unscented household bleach per gallon of water, followed by air drying.
Returning to Normal Water Use
Once the boil water advisory is lifted, the plumbing system must be flushed. Run all cold water faucets continuously for a minimum of five minutes to clear the pipes of any compromised water. For homes with a water heater, flush the hot water lines by running the hot water tap for 15 to 30 minutes, depending on the tank size, to ensure the entire volume is replaced.
Any ice made during the advisory period must be thrown out. The ice maker should be run to create and discard three full batches of new ice. Refrigerator water dispensers should be flushed by dispensing at least one quart of water. Stored boiled water should be discarded, and any disposable water filters used during the contamination period should be replaced.