A boil water advisory (BWA) is a public health announcement issued when a community’s water supply is contaminated with harmful germs, such as bacteria, viruses, or parasites. These advisories are typically issued following events like water main breaks or natural disasters that compromise the water system. Using untreated tap water for washing dishes is unsafe because it risks contaminating surfaces that will touch food or your mouth. Safe dishwashing methods exist for both manual and mechanical processes, but they require specific sanitation steps beyond normal washing.
Why Tap Water is Unsafe for Dish Cleaning
The danger in a boil water advisory lies in the presence of pathogens, which are not killed by standard dish soap and warm water. Microorganisms such as E. coli, Giardia, and Cryptosporidium can be present in the water supply and pose a significant health risk if ingested. Washing dishes with contaminated water transfers these germs directly onto plates, cups, and utensils.
When dishes are washed in untreated tap water, the pathogens can survive the wash and rinse cycle, remaining on the surface. Subsequent use of these dishes creates a direct route for infectious organisms to enter the body. This contamination risk is why all food-contact surfaces, including dishes and food preparation areas, must be sanitized during a BWA.
The BWA aims to prevent the transmission of waterborne diseases that cause gastrointestinal issues. Standard household water temperatures are insufficient to destroy these pathogens. A specific final sanitization step is required for all washed items because they are not microbiologically safe without proper disinfection.
Safe Handwashing Procedures
Washing dishes by hand during an advisory requires a two-step process: cleaning followed by chemical sanitization. First, wash and rinse the dishes as you normally would, using hot tap water and dish soap to remove food debris. This initial step removes organic matter that could interfere with the disinfectant’s effectiveness.
The sanitization step involves preparing a separate basin with a diluted bleach solution. For every gallon of warm water, add one teaspoon of unscented household liquid bleach (5–9% sodium hypochlorite).
Dishes must be fully submerged in this sanitizing solution for at least one minute to ensure pathogen inactivation. Do not rinse the dishes with untreated tap water after soaking. Remove them from the solution and allow them to air-dry completely before use.
Using Mechanical Dishwashers Safely
Using a mechanical dishwasher is safe only if the appliance meets a specific temperature requirement. The dishwasher must reach a final rinse temperature of at least 150°F (66°C) to effectively kill germs present in the water. Many modern dishwashers include a “sanitizing cycle” or “high-temperature wash” option that meets this standard.
If your dishwasher has a sanitizing cycle, activate it to ensure the water reaches the necessary temperature for disinfection. If your machine lacks this setting, check the appliance manual or contact the manufacturer to confirm the final rinse temperature. A final rinse at 150°F or higher provides the thermal energy required to inactivate waterborne bacteria and viruses.
If the dishwasher cannot reach the minimum temperature, or if you are unsure of its capability, the machine should not be used. If a non-sanitizing dishwasher is used, the dishes must be treated afterward using the chemical bleach solution method intended for handwashing. Also, avoid using water-connected appliances like refrigerator ice or water dispensers during the advisory.