Is my Water Safe (WO1031)

October 20, 2015

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A disaster may disrupt the electricity needed to pump water in the home and/or contaminate the water supply. Planning ahead can assure there is enough safe water for drinking, preparing food, brushing teeth and keeping clean.

Water storage

You can store water ahead for use in emergencies. Boiled water, stored in sterilized containers, will keep for 6 months to 1 year. The water may taste flat, but it is safe to drink or use in cooking.

Commercially bottled water is best to use, if possible. Store in a cool, dry, dark place.

The recommended amount of water to be stored is 1 gallon of water per person per day for drinking. Additional water is needed for food preparation and hygiene. Store at least 1/2 gallon per person per day for these purposes. Store at least a 2 day supply or as much as space allows.

Emergency water

Your hot water heater or water pressure tank could supply many gallons of safe water during an emergency. Before using water from the water heater, switch off the gas or electricity that heats the water. Leaving the power on while the heater is empty could cause an explosion or burn out the elements. After turning off the power source, open the drain valve at the bottom of the tank. Do not turn the water heater on again until the water system is back in service.

Water from the toilet tank may be used for drinking unless a chemical tank cleaner has been added to the water.

Unless you are absolutely certain your water supply is not contaminated, all water should be purified before being used for drinking, preparing food, brushing teeth or washing dishes. If the water contains sediment or floating material, strain it through a cloth before purifying it.


Boil water at a rolling boil for 10 minutes to kill any disease-causing bacteria. Add a pinch of salt to each quart of boiled water to improve taste.

Chemical treatment

Any of the following chemical treatments will purify water and make it safe for drinking:

Chlorine bleach — Household bleach is a good disinfectant for water. Before using, check the label to be sure hypochlorite is the only active ingredient in the bleach. Do not use bleach that contains soap. The amount of chlorine in bleach is variable, so use the following table to determine the appropriate amount needed to purify water. Mix the bleach thoroughly in the water and let it stand for 30 minutes. The water should have a slight chlorine odor. If it doesn’t, repeat the dose and let the water stand for an additional 15 minutes.

Percent Chlorine

Add per gallon water


40 drops

2 to 6%

8 drops

7 to 10%

4 drops

Iodine — Household iodine from the medicine cabinet will purify water. The iodine should be 2% U.S. pharmacopeia (U.S.P.) strength. Add 20 drops per gallon of clear water and 40 drops per gallon of cloudy water.

Water purification tablets — These tablets are available at drug stores. Follow the manufacturer’s instructions.

For more information about safe food handling and preparation:

FDA’s Food Information Hotline
1-888-SAFEFOOD (1-888-723-3366)

USDA’s Meat and Poultry Hotline

FDA’s Food Information and Seafood Hotline

United States Food Safety Web Site

The Food Domain. Michigan State University

Extension Disaster Education Network

Federal Emergency Management Agency

Related Topic Areas

Safe Food & Water, Food & Health


Joyce McGarry

Joyce McGarry

Joyce McGarry

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