Bacterial Contamination Safety Recommendations for Residential Water Use

In a situation in which the drinking water in a residence is found to contain unacceptably high levels of bacteria, the occupant is advised to follow the recommendations listed below: 

Safety Recommendations 

1. Drinking Water and Food Preparation  

• Bring all drinking water to a rolling boil for two minutes. Boil all water used for washing fruits or raw vegetables, ice cubes, brushing teeth, preparing formula, making juices, or preparing tea or coffee.  
• Use boiled water for cooking all foods that will not be heated to boiling temperature (100°C/212°F) for at least two minutes. Bottled water is acceptable and can be used instead of boiled water.  
• DO NOT rely on automatic shut-off kettles because they do not boil water long enough to be safe.  
• DO NOT rely on point-of-use treatment filter devices that fit onto taps (these include water softeners, reverse osmosis devices or sediment/charcoal filter devices) as they may not eliminate bacteria.  

2. Bathing  

Showering and tub bathing are allowable if you are sure the person's skin has no open wounds and that they will NOT consume the water. Showering and tub bathing are NOT recommended if the person is immunocompromised.  

Where conditions are such that individuals may be at risk of swallowing bath water, tub bathing using disinfected water is recommended. To disinfect water for bathing, add 1 oz./30 mL of 5.25 % household bleach to an average size bathtub half filled with water. Mix well and let stand for 15 minutes before bathing. Larger-sized tubs, such as hot tubs, will require more disinfectant. In extreme circumstances, sponge bathing with boiled or bottled water may be necessary. 

3. Handwashing  

Handwashing is always important after using the washroom and before preparing or handling food – but what if the water is contaminated? Hands may be washed with boiled/bottled water. Another option is to wash hands with tap water as usual, and then follow one of the additional steps below:  

• Thoroughly wipe hands with an alcohol-based antiseptic wipe;  
• Apply a liquid hand sanitizer (available at most department/drug stores) to hands; or 
• Immerse hands in water disinfected with 5.25% liquid bleach (1tsp./1L water) for a few seconds.  

Please NOTE that if water is grossly contaminated, do NOT wash your hands with the tap water before using one of the options identified above. 

4. Humidifiers  

• A disinfectant should be added to humidifiers as per the directions of the manufacturer. If disinfectant cannot be added at the recommended strength, the humidifier should be turned off until the water supply is clear of bacteria.  
• For buildings with mechanical ventilation systems, it is recommended that the humidity control portion of the system be turned off until the bacterial contamination problem has been rectified.  

5. Dishwashing  

• Dishes may be safely washed in hot water and dish detergent. Once dishes are washed, fully rinse and then treat the dishes by soaking for a minimum of two minutes in a solution of 1 oz./30 mL liquid household bleach to three gallons/14 litres, or an average sink full, of water.  
• For domestic mechanical dishwashers, add 1 oz./30 mL of liquid household bleach (5.25%) to the final rinse cycle.