A boil water advisory (BWA) is a public health announcement issued when harmful microbiological pathogens, such as bacteria or parasites, are known or potentially present in the public water supply. These advisories are typically precautionary measures following events like water main breaks, pressure loss, or flooding that could compromise water system integrity. The advisory’s primary purpose is to protect the public from waterborne illnesses by recommending that all tap water used for consumption be brought to a rolling boil first. Running a household dishwasher is generally acceptable, provided the appliance can meet specific temperature conditions.
Understanding Dishwasher Efficacy During an Advisory
A modern household dishwasher can safely clean and sanitize dishes during a BWA because the machine’s internal heating elements can reach temperatures that inactivate the targeted pathogens. The safety of using the appliance relies on its ability to heat the water high enough to provide thermal disinfection. For most household models, the final rinse cycle must achieve a water temperature of at least 150°F (66°C).
Many newer dishwashers are equipped with a “Sanitize” or “High-Temp Wash” cycle specifically designed to meet this standard. This setting extends the cycle time and utilizes the internal booster heater to ensure the water maintains the necessary temperature for a duration long enough to inactivate bacteria and protozoa. If your dishwasher has this certified sanitizing cycle, running it during a BWA is considered a safe method for cleaning dishes.
Standard dishwasher cycles often use lower temperatures to save energy. Since the water coming into the appliance is contaminated tap water, it must be heated sufficiently to provide thermal disinfection in the final stage. You should consult your appliance manual or the manufacturer’s website to confirm if your model can reliably reach and maintain the 150°F (66°C) final rinse temperature.
Steps for Dishwashers Lacking a Certified Sanitizing Cycle
If your dishwasher is an older model or lacks a confirmed high-temperature setting, assume the machine cannot meet the thermal disinfection standard. You must rely on alternative methods, such as handwashing, where the most effective non-heat method for sanitizing dishes is chemical disinfection using unscented household bleach.
Handwashing with Bleach
To handwash safely, first wash and rinse the dishes with hot, soapy tap water to remove food debris. After rinsing, soak the cleaned dishes in a separate basin containing a diluted bleach solution for at least one minute. This solution requires approximately one teaspoon of unscented household liquid bleach mixed into one gallon of warm water.
Following the chemical soak, dishes should not be rinsed again with untreated tap water, as this would reintroduce potential contaminants. The items must be allowed to air dry completely before being used again.
Using Pre-Boiled Water
Alternatively, water that has been brought to a rolling boil for one minute and then allowed to cool can be used for the washing and final rinse steps.
Related Kitchen Water Safety Considerations
Beyond the dishwasher itself, several other precautions should be taken to ensure kitchen safety during a BWA. Air-drying dishes after any cleaning method is important to allow any remaining moisture to evaporate, which assists in preventing microbial growth.
You should avoid using any appliances or fixtures that might aerosolize the contaminated water, such as a sink sprayer, which can create fine droplets that are easily inhaled or ingested.
Water-using equipment with direct line connections must be addressed, as these appliances do not reach sanitizing temperatures:
- Ice makers should be turned off and the existing ice discarded.
- Water dispensers should be turned off.
For all other kitchen uses, such as washing produce or making coffee, only bottled water or water that has been properly boiled and cooled should be used.