A boil water advisory (BWA) is a public health announcement issued by local water authorities when the drinking water quality is, or may become, compromised. These advisories are typically issued following events like a major water main break, significant loss of water pressure, or equipment failure at a treatment plant. They can also be triggered by initial test results suggesting the presence of harmful microorganisms, such as bacteria, viruses, or parasites. The immediate concern is the potential for waterborne infectious agents, like E. coli or Giardia, which can cause gastrointestinal illness. A BWA informs the public that tap water must be treated before consumption to kill these potential pathogens.
Safeguarding Ingested Water
Boiling is the most reliable method for making tap water safe to drink during an advisory, as the high heat effectively destroys disease-causing organisms. To properly disinfect water, bring it to a vigorous, rolling boil for at least one full minute at sea level. For locations above 6,500 feet, extend the boiling time to three minutes to ensure sufficient purification.
After boiling, allow the water to cool naturally before consumption. Store the cooled, safe water in clean, sanitized, and tightly covered containers to prevent recontamination. This treated water must be used for all forms of ingestion, including preparing beverages, concentrated juices, and making ice. Existing ice cubes made with potentially contaminated water should be discarded immediately.
If boiling is not feasible, chemical disinfection can serve as a temporary alternative, though it is less effective against parasites like Cryptosporidium. Use regular, unscented household liquid chlorine bleach containing 6% to 8.25% sodium hypochlorite, ensuring it contains no added cleaners or scents. For clear water, add eight drops of 6% bleach, or six drops of 8.25% bleach, per gallon of water.
After adding the bleach, stir the mixture thoroughly and allow it to stand for a minimum of 30 minutes before use. The water should have a faint chlorine smell; if not, repeat the dosage and allow it to stand for another 15 minutes. Disinfecting tablets containing chlorine or iodine are also available and should be used according to the manufacturer’s instructions. Bottled water from an approved source remains the simplest and safest option for ingestion during an advisory.
Safe water must also be used for all food preparation, including washing fruits and vegetables that will be eaten raw. For infants, ready-to-use formula is the preferred option during a BWA. If powdered or concentrated formula must be prepared, it should be mixed only with bottled water or tap water that has been properly boiled and cooled.
Hygiene and Household Use During the Advisory
Precautions extend beyond drinking and food preparation to nearly all household activities involving water contact. Oral hygiene is a particular concern; brushing teeth requires using bottled water or water that has been boiled and cooled. Tap water should not be used for rinsing the toothbrush or the mouth.
When washing dishes by hand, the final rinse must be a disinfecting one. This can be achieved by soaking the washed and rinsed dishes in a separate basin containing a mixture of one teaspoon of unscented household liquid bleach per gallon of warm water for at least one minute. Alternatively, dishwashers are safe to use if they have a sanitizing cycle or if the final rinse temperature reaches at least 150°F.
Bathing and showering are safe for most adults, provided the water is not swallowed. Individuals should keep their mouths closed and avoid letting water enter their eyes or open wounds. For infants, toddlers, and those with compromised immune systems, use sponge baths to prevent accidental ingestion of tap water.
Pets must be protected from potential pathogens; all animals should be given boiled and cooled water, or bottled water. Laundry is safe using tap water, as the elevated temperatures and detergent action in washing cycles are sufficient to kill most contaminants. Using the highest effective temperature setting for the fabric is advisable.
Returning to Normal Water Use After the Advisory
Once the boil water advisory has been officially lifted by the water utility, flush the home’s plumbing system to clear out any remaining contaminated water. Start by running all cold water faucets for a minimum of five minutes to ensure the lines are filled with fresh, safe water.
Appliance cleaning is an important step in the transition back to normal use. Water-using appliances must be purged and sanitized. Run the water dispenser on refrigerators until the tank is empty. Automatic ice makers should be cycled, and the first three batches of ice produced must be discarded.
Coffee makers should be flushed by running a brewing cycle with clean water, without coffee grounds, and then discarded. All water filters, such as those in refrigerators, pitchers, or faucets, should be replaced immediately. Filters may have trapped contaminants during the advisory, and continuing to use them poses a risk of reintroducing pathogens.