Disinfecting water at the household level is important to eliminate harmful microorganisms and make it safe to drink. Two widely used and effective methods are boiling and chemical disinfection, such as chlorination.
Ensuring the safety of drinking water at home is a critical step in preventing waterborne illnesses. Simple techniques can effectively treat water from various sources, killing bacteria, viruses, and protozoa that can cause health problems.
Chlorination
Chemical disinfection using chlorine is a common and often readily available method for treating water at home.
A common and relatively inexpensive method of disinfecting water is chlorination, where a solution of chlorine or hypochlorite is added to the water. The reference points out that this method is effective against many pathogens. Specifically, the method kills disease-causing microorganisms including bacteria and certain viruses but does not kill the protozoa Cryptosporidium, Giardia, and some others.
To disinfect water using liquid household bleach (typically 5-6% sodium hypochlorite):
- Use only plain, unscented chlorine bleach that has been stored away from light and heat. Check the label for the percentage of available chlorine.
- Add 8 drops of bleach per gallon of clear water (or 16 drops per gallon of cloudy water). This is roughly equivalent to 1/8 teaspoon per gallon for clear water or 1/4 teaspoon per gallon for cloudy water.
- Stir the water thoroughly and let it stand for at least 30 minutes.
- The water should have a slight chlorine odor. If not, add another dose and let it stand for another 15 minutes.
Boiling
Boiling is a highly reliable method for disinfecting water as the heat kills all types of pathogens, including bacteria, viruses, and protozoa.
To disinfect water by boiling:
- Bring the water to a rolling boil.
- Maintain the rolling boil for at least one minute.
- If you are at altitudes above 6,500 feet (2,000 meters), you should boil the water for three minutes because water boils at a lower temperature at higher elevations.
- Let the water cool naturally before drinking. Boiling can sometimes make water taste flat; you can improve the taste by pouring the cooled water back and forth between two clean containers.
Other Household Disinfection Techniques
While boiling and chlorination are primary methods, other techniques are also used:
- Solar Disinfection (SODIS): This method uses sunlight and PET plastic bottles to disinfect water. Fill clear plastic bottles with water and expose them to direct sunlight for at least six hours (or two days if cloudy). UV radiation and heat from the sun kill pathogens.
- Water Filter Systems: Various household filters exist, from faucet filters to pitcher filters and complex under-sink systems. It's important to note that not all filters disinfect water. Look for filters certified to remove or inactivate microorganisms like bacteria, viruses, and protozoa.
The choice of method depends on the specific situation, the quality of the raw water, and available resources. Sometimes, combining methods, like filtering followed by boiling or chlorination, provides an extra layer of safety.
