6 ways to purify drinking water in emergency situations

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In an emergency situation where regular water service has been interrupted – like a hurricane, flood or water pipe breakage – it is not only important to have a water supply, but also to have ways of treating water if needed.

“Even if the water looks clear, [it] could have organisms in it that could make you sick. It's not only humans that shed organisms that make you sick, but some animals have organisms in their gut that can make people sick,” Jonathan Yoder said, MPH, deputy chief of Centers for Disease Control’s Waterborne Disease Prevention Branch.

Local authorities may recommend using only bottled water, boiled water or disinfected water until regular water service is restored. Contaminated drinking water is one of a number of pathways through which humans can ingest pathogens from fecal matter. Chemical remnants are another main concern.

Water purification methods depend on what you are trying to treat, for example, bacterial or chemical contamination, odor, color, taste.

"Some chemical pollutants, such as fluoride and arsenic, are naturally occurring in groundwater. Other pollutants can find their way into water through man-made activities such as overuse of fertilizers in water catchment areas, indiscriminate discharge of aquifers, environmental pollution," Hrachya Sargsyan, a UNICEF water, sanitation and hygiene specialist, said.


One of the easiest and most well known ways to make sure water is safe to drink is by boiling it. The high temperature kills bacteria and viruses; however, it does not remove any sediment, dirt or particles.

"Boiling or disinfection will not destroy other contaminants, such as heavy metals, salts and most other chemicals," an Environmental Protection Agency (EPA) spokesperson said.

If the water is cloudy, let it settle and filter it through a clean cloth, paper towel or coffee filter.

How to treat water by boiling:

  • Bring water to a rolling boil for at least one minute. At altitudes above 5,000 feet (1,000 meters), boil water for three minutes.
  • Let water cool naturally and store it in clean containers with covers.
  • Add one pinch of salt to each quart or liter of water, and pour the water from one clean container to another several times.


Purifying water can be accomplished by passing water through a bed of sand and gravel. As water filters through the sand, the remaining particles of suspended matter are trapped in the sand bed. However, there are many household filters that are great to keep on hand.

“There are a lot of commercial filters that remove pathogens, so it is important to read the label and understand [what it] is designed to remove. For example, some remove parasites and bacteria but not viruses because viruses are much smaller organisms," Yoder said.


This powder is a coagulant made from fermented soybeans that makes water cleaner. It sticks to dirt and pollutants, causing the dirt in the water to separate from the water and sink.

One gram can treat up to 5 liters of polluted water; however, the water is still not fully purified and still requires further filtering to be safe to drink.

Chemical disinfection: Chlorination, iodine and bleaching

You can disinfect water with tablets that contain chlorine, iodine, chlorine dioxide or other disinfecting agents. These tablets are available online or at pharmacies and sporting good stores. Follow the instructions on the product label as each product may have a different strength.

“You can buy chlorine tablets at a camping store or outdoor store [and these] would be good to keep on hand," Yoder said.

To disinfect water, add one part of the chlorine solution to each 100 parts of water you are treating. This is about the same as adding 1 pint (16 ounces) of the chlorine solution to 12.5 gallons of water. If the chlorine taste is too strong, pour the water from one clean container to another and let it stand for a few hours before use.

Iodine tablets

Iodine tablets make most water suitable, in terms of bacterial levels, for drinking. It is recommended to use iodine tablets instead of iodine you may find in a first aid kit.

Iodine tablets are also available in the same stores you will find chlorine tablets, Yoder said.

However, according to Yoder, pregnant women and people with thyroid issues should avoid this method.

How to use iodine properly to purify water, according to the CDC:

  • Add five drops of 2 percent tincture of iodine to each quart or liter of water that you are disinfecting.
  • If the water is cloudy or colored, add 10 drops of iodine.
  • Stir and let the water stand for at least 30 minutes before use.


If you can’t boil water, disinfect water using household bleach. Only use regular, unscented chlorine bleach products that are suitable for disinfection and sanitation as indicated on the label.

"Do not use scented, color safe, or bleaches with added cleaners. If water is cloudy, let it settle and filter it through a clean cloth, paper towel, or coffee filter," an EPA spokesperson said.

Instructions for using bleach to clean water:

  • Locate a clean dropper from your medicine cabinet or emergency supply kit.
  • Locate a fresh liquid chlorine bleach, or liquid chlorine bleach that is stored at room temperatures for less than one year. The label should say that it contains 8.25 percent of sodium hypochlorite.
  • Add six drops of bleach to each gallon of water. Double the amount of bleach if the water is cloudy, colored or very cold.
  • Stir and let stand for 30 minutes. The water should have a slight chlorine odor. If it doesn’t, repeat the dosage and let stand for another 15 minutes before use.
  • If the chlorine taste is too strong, pour the water from one clean container to another and let it stand for a few hours before use.

Sargsyan said to ensure safe drinking water, national water quality standards should apply based on World Health Organization (WHO) Guidelines for Drinking Water Quality.

"The safety of drinking water is an important precondition for survival and development and prevention of water-borne and preventable diseases," Sargsyan said.

According to the EPA, citizens who are concerned about their drinking water and who are served by a public water system can contact their local water supplier and ask for information on contaminants in their drinking water for their Consumer Confidence Report.

For more safety and preparedness tips, visit AccuWeather.com/Ready.