A Boil Water Advisory (BWA) is a public health announcement issued when the drinking water supply may be contaminated with microorganisms. This measure is put in place following events like water main breaks, power outages, or flooding, which allow pathogens to enter the distribution system. When the advisory is lifted, municipal testing confirms the water is microbiologically safe. However, lifting the advisory does not mean household water systems are immediately clear. A series of flushing and cleaning steps must follow to ensure the safety of your home’s water supply.
Clearing the Plumbing Lines
The first step after an advisory is lifted is to remove any potentially contaminated water standing in your home’s plumbing and fixtures. This process, known as flushing, replaces the old water in the lines with the newly confirmed safe water supply. Begin by running all cold water faucets for a minimum of five minutes, starting with the one furthest from where the water enters your home. This duration ensures the entire volume of water within the pipes is completely replaced.
For complex or long service connections, a longer flushing time may be necessary. Also run water through outdoor hoses, showers, and other cold water spigots to clear all potential points of stagnant water.
The hot water system requires a more substantial flushing effort due to the volume held within the water heater tank. For a typical 40-gallon hot water tank, flush the hot water line for at least 15 minutes to completely replace the water inside. Larger 80-gallon tanks may require 30 minutes of flushing.
Cleaning Water-Holding Appliances
Once the plumbing lines are clear, address household appliances that store or process water, as they may still harbor contaminants. Empty all existing ice made during the advisory period from the ice maker. Flush the water feed lines by running the machine through three full cycles and discarding the ice from each batch.
Coffee makers and kettles also contain internal reservoirs. Run a cleaning cycle using a descaling solution, such as white vinegar, or a mild bleach solution if recommended by the manufacturer. Follow this with at least two full cycles using fresh water to rinse away any residual cleaning agents.
Run appliances like dishwashers and washing machines empty on their highest heat setting to sanitize internal components. This high-temperature cycle disinfects the lines and internal workings that contacted the untreated water. Water-based medical devices, such as humidifiers and CPAP machines, must have their reservoirs emptied and thoroughly cleaned or disinfected according to the manufacturer’s directions before being refilled.
Managing Filters and Water Softeners
Physical filtration media and water treatment systems require specific attention because they may have trapped harmful microorganisms. Water filters, including those in refrigerators, pitchers, under-sink units, and whole-house systems, must be replaced. If bacteria or viruses entered the system, they may remain embedded in the filter cartridge, rendering the filter ineffective or contaminated.
For water softeners, the resin bed may have been exposed to contaminants and needs cleaning. Initiate a full regeneration cycle, which flushes and cleans the resin media and the brine tank. Consult the manufacturer’s manual for the specific procedure to run this cycle. Reverse osmosis (RO) systems also require draining the storage tank, sanitizing the system, and replacing the RO filters.