Water Issues in an Emergency

Emergency Water Storage

In a disaster such as a large magnitude earthquake or severe flooding, water systems will most likely suffer damage and safe water will not be available. Be prepared by storing a supply of water for each family member. One gallon per person per day provides enough for drinking. Two to three gallons per person per day covers drinking, first aid, limited personal hygiene and cooking needs. Plan to have enough water for your family for at least 3 days. Consider water provisions for pets as well.

Water should be stored in plastic containers, preferably heavy opaque plastic with tight fitting, screw-on caps. Mark date on containers when stored and place in a cool dark location. Stored tap water should be replaced every six months. Unopened commercial bottled water can be stored for up to a year. If you need to consume water stored longer than these recommended times, use one of the methods described below to purify it.

Emergency Water Sources

A typical household water heater tank holds a supply of 30 to 60 gallons. This can be accessed in an emergency. After shutting off the main valve from the tank to the household to depressurize the tank, it is advisable to vent the tank by opening a hot water faucet or disconnecting the hot water line at the top of the heater. Turn off gas or electricity to the tank before draining.

Other sources of water can be melted ice cubes, toilet reservoir tanks (without disinfectants), and juices from canned foods. Water from swimming pools and spas is not for drinking, but can be used for washing and other purposes.

How to Purify Water

Boil water vigorously for 3 to 5 minutes. To improve taste, pour from one container to another several times to aerate.

Use purification tablets. These are available at most drug stores. Follow directions on the package.

Use bleach for purification. Liquid household bleach (5.25% sodium hypochlorite) can be used. Add bleach according to the table below. Mix thoroughly and let stand for 30 minutes.

Purify Water

Amount of Water
Clear Water
Cloudy Water
1 Quart
2 drops
4 drops
1 Gallon
8 drops (1/4 teaspoon)
16 drops (1/2 teaspoon)
5 gallons
40 drops (1-1/4 teaspoons)
80 drops (2-1/2 teaspoons)

Contamination from Flood Waters

Flood waters are likely to be contaminated. All persons should avoid direct contact with all flood waters. If contact is made, good personal hygiene including washing of hands and avoiding hand-to-mouth contact will limit any potential health risk.

In the event of flooding or significant sewage discharge inside or near inhabited buildings, the following safety precautions and methods for cleaning and disinfecting should be borne in mind.

  • Avoid ingestion of contaminated food or water, or contact with contaminated surfaces.
  • Children should be kept away from flood areas and flooded buildings.
  • Wash hands thoroughly after working at flood sites or after contact with flood water.

Gas & Electric

PG&E recommends that persons who are evacuating their homes due to a flood turn off their gas and electric supply if they know how to do so safely. In other emergency situations such as an earthquake, shutting off gas should be done only if you smell gas, hear gas escaping, see a broken gas line or suspect a gas leak due to structural damage. Keep in mind that once you have turned off the gas supply, PG&E recommends that service be restored by their personnel and it may be some time before a PG&E representative responds to your request.

Shutting off the electrical supply can be done at your circuit breaker box or fuse box. Never touch these boxes if your feet are wet or if you are standing in water.