A boil water advisory is a public health notification issued by authorities, advising people to boil tap water before consumption. This measure is implemented when there is a potential or confirmed degradation in the public water supply’s quality, aiming to prevent consumption of water that may contain harmful microorganisms.
Reasons for Issuance
Boil water advisories are triggered by events that compromise the water distribution system. These include water main breaks, which lead to a loss of pipe pressure, allowing contaminants to enter. Power outages affecting water treatment plants can also disrupt disinfection processes.
Natural disasters like floods can introduce harmful substances and microorganisms, such as E. coli or Giardia, into water sources and distribution networks. Advisories are issued as a precautionary measure due to potential risk or as a mandatory directive when contamination, like confirmed bacteria, is detected through testing.
Determining Duration
There is no fixed duration for a boil water advisory; its length depends on the specific cause and the time required for corrective actions and water testing. Water utilities must first address the underlying issue, such as repairing a water main break or restoring treatment plant operations. Following repairs, the water system is often flushed to clear out any remaining compromised water.
The most significant factor determining duration is the water quality testing process. Samples are collected from various points in the affected area and sent to certified laboratories for analysis, typically looking for indicator bacteria like total coliforms or E. coli. These bacterial analyses usually require a minimum of 24 to 48 hours to yield results. For an advisory to be lifted, authorities generally require at least two consecutive sets of clear samples, taken 24 hours apart, confirming the absence of contamination. This rigorous testing protocol explains why advisories rarely last less than 48 to 72 hours, often extending for several days or longer, depending on the severity of the initial event and the time needed for consistent clean results.
Lifting an Advisory
A boil water advisory is lifted only after water quality tests consistently confirm the water supply is safe for consumption. Once safety is confirmed, the water utility or local health authorities will officially announce the lifting of the advisory.
Public notification is typically disseminated through official channels, including local government websites, news outlets, and direct alerts to affected residents. It is important for individuals to wait for this official confirmation before resuming normal water use, even if the water appears clear.
Safety Measures During and After
During a boil water advisory, it is important to take precautions to protect health. All tap water intended for drinking, cooking, making ice, brushing teeth, or washing produce must be brought to a full rolling boil for at least one minute, then allowed to cool before use. Bottled water can serve as a safe alternative for these purposes. For bathing, adults can shower or bathe but should avoid swallowing water, while young children or individuals with open wounds might consider sponge baths. Dishes can be washed by hand using hot, soapy water, followed by a one-minute soak in a diluted bleach solution (one teaspoon of unscented household bleach per gallon of water), then air-dried.
Once the advisory is lifted, several steps are recommended to clear household plumbing of any potentially stagnant or contaminated water. This includes flushing cold water faucets for at least five minutes and hot water faucets for 15 minutes for a typical 40-gallon tank.
Appliances that use water, such as ice makers, dishwashers, and water filters, also require attention. Ice made during the advisory should be discarded, and ice makers should be flushed by making and discarding several batches. Water filters in refrigerators or other devices should be replaced, as they may have trapped contaminants. Running an empty dishwasher through a hot or sanitize cycle is also advised.