Why should I disinfect my drinking water?
Water from lakes, rivers, or streams and many groundwater sources may contain disease-causing germs. Germs, or pathogens, can lead to waterborne infections. Waterborne illnesses can lead to severe reactions and serious complications, including death. Waterborne infections can spread when animal or human feces containing these pathogens get into drinking water. These pathogens may include bacteria, viruses or parasites (such as Campylobacter, Salmonella, Giardia and Cryptosporidium).
Disinfection kills or removes pathogens from drinking water, reducing health risks. You can disinfect water by adding chemicals, using heat, using ultraviolet (UV) radiation, filtration or a combination of these methods.
When should I disinfect my drinking water?
In most cases, drinking water suppliers disinfect water to make it safe. You may need to disinfect your own drinking water or find an alternate source such as bottled water if your community is on a ‘boil water’ notice. This may be because:
- The water does not have adequate treatment
- Tests show the presence of “fecal coliform” or Coli bacteria, an indicator of human or animal waste
- A flood, fire, earthquake or other event has disrupted the water supply in your community
You may also need to disinfect your water if:
- You are on your own water supply or source
- You are travelling in an area where the safety of the water is questionable
- You have a weakened immune system
What is the best way to disinfect water?
Boiling water is the most effective way to disinfect water, particularly if you think your water has parasites such as Giardia or Cryptosporidium, or if you have a weakened immune system.
- Boil water for at least one minute. At elevations over 2,000 meters (6,500 feet) boil water for at least 2 minutes
- Store disinfected water in clean, covered, food-grade containers
Can I use bleach to disinfect water?
Yes. Household chlorine bleach kills most pathogens.
- Do not use scented bleaches, colour-safe bleaches, bleaches with added cleaners or non-chlorine bleach
- Bleach works best when added to warm water that is about 20˚C (68˚F). Mix:
- 2 drops (0.1 mL) of household bleach (about 5.25% chlorine)
- 1 litre (4 cups) of water
Cover and let stand for 30 minutes before drinking. You should notice a slight chlorine smell after the 30 minutes. If not, add another 2 drops. Let the water stand for another 15 minutes.
- If the water is cloudy, or colder than 10˚C (50˚F), double the amount of bleach added. Cover it and let it stand for one to 2 hours before drinking. The longer the treated water stands the better it works to disinfect the water
- To reduce chlorine taste, let the water stand uncovered for a few hours, or pour it back and forth from one clean container to another several times
- If using chlorine tablets, follow the directions on the package
What if the water is heavily contaminated or polluted with chemicals?
Boiling water or adding bleach does not make heavily contaminated water safe because it does not remove chemicals. You must find an alternate safe potable source of water.
What if the water is cloudy or murky?
Cloudy water can reduce the effectiveness of a disinfectant, so it is important to clarify water as a first step. Reduce cloudiness by pouring the water through a clean cloth or coffee filter. Let any remaining bits settle to the bottom. Pour off the clear water into clean containers and then disinfect.
Can I use iodine to disinfect water?
Yes, but only for short periods of time. There are potential health concerns (thyroid problems or iodine sensitivity) associated with long-term iodine use. Children and pregnant women are especially sensitive and should avoid using iodine to disinfect water.
- Iodine works best when added to warm water that is about 20˚C (68˚F). Mix:
- 6 drops (0.3 mL) of 2% Tincture of Iodine
- 1 litre (33 oz.) of clear untreated water
Let the water stand for 30 minutes before drinking. For cold water, let it stand for several hours before drinking.
- If the water is cloudy, mix:
- 10 drops (0.5 mL) of 2% Tincture of Iodine
- 1 litre of water
- If using iodine tablets, follow the directions on the package
Can I use a water filter to disinfect water?
Jug-type water filters (such as Brita®) are not made to remove pathogens from an unsafe water supply. You may consider using a treatment device that is certified to kill or remove pathogens. For information on certification of treatment devices, visit the National Sanitation Foundation (NSF) website at www.nsf.org.
What should I use treated or bottled water for?
If you need to disinfect your water, use treated or bottled water for the following activities:
- Drinking and food preparation. This includes cleaning raw vegetables and fruit, as well as making baby formula
- Drink mixes such as juice concentrates or drink crystals
- Coffee
- Ice cubes (freezing does not kill or remove pathogens)
- Hand washing dishes. If using a dishwasher that does not have a hot or sanitation cycle, soak the dishes afterwards for one minute in a solution of 2 mL of bleach per litre of water
- Brushing your teeth
- Filling pet dishes
- Bathing children - as they are more likely to ingest water, give sponge baths using disinfected water instead
Adults can bathe using water that has not been disinfected, but they should not swallow the water. After bathing, wash your hands with disinfected water or use an alcohol-based hand sanitizer.
For more information
If you have questions about your drinking water, contact your local environmental health officer or your local health authority.
For more information, please visit the following HealthLinkBC Files:
