Preparing for an Emergency

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We often take our household water supply for granted. However, when safe drinking water is unavailable, it is more than just an inconvenience — it can become a health emergency. In Southern California, a large-scale earthquake may interrupt the supply of safe drinking water at any time. The interruptions may last for a short period of time, or for several days. Every household should have an emergency water supply to meet its members' needs. Click here to learn how SMWD is prepared in the event of an emergency.

How Much Water Should I Store?

Having an ample supply of clean water is a top priority in an emergency. Needs may differ depending upon age, physical condition, activity, diet and climate. Most people need to drink at least two quarts (half gallon) of water each day. Children, nursing mothers, and ill people will need more water.

You will also need water for food preparation and hygiene. Store at least one gallon of water per person, per day. If you have pets, allow 1 quart per day for each dog or cat. Storing at least a three-day supply is recommended, but consider storing a two-week supply if your home has enough space for it.

Preparing and Storing an Emergency Water Supply

To prepare the safest and most reliable emergency water supply, it's recommended that you purchase commercially bottled water. Keep bottled water in its original container, and do not open until you need to use it. You will also want to observe the expiration date. If you are preparing your own containers of water, you should purchase food-grade water storage containers from surplus or camping supply stores. Containers not labeled for food or beverage storage could release harmful chemicals into the water. Never use a container that has held toxic substances.

If you decide to re-use storage containers, choose two-liter plastic soft drink bottles — not plastic jugs or cardboard containers that have had milk or fruit juice in them. Milk protein and fruit sugars cannot be adequately removed from containers and provide an environment for bacterial growth. Thoroughly clean the bottles with dishwashing soap and water, and rinse completely so there is no residual soap. Then sanitize the bottles by adding a solution of 1 teaspoon of non-scented liquid household chlorine bleach to a quart of water. Rinse out the sanitizing solution thoroughly using clean water.

Can I Store My Tap Water?

Yes, the water SMWD supplies to its customers for drinking and cooking is suitable for storing for emergencies. Remember that the container used to collect and store the water must also be clean. Place a date on the outside of the container so you know when you filled it. Store in a cool, dark place and replace the water every six months if not using commercially bottled water.

For more information regarding emergency drinking water supplies, visit

After an Emergency Strikes

Following an emergency or natural disaster, take the following steps to ensure that you and your family’s water supply remains safe:

  • Check inside and outside your home for obvious water leaks.
  • If you smell gas or suspect a gas leak, turn off your main gas valve.
  • Immediately shut off your house’s main water valve. This will keep the water in your water heater from becoming contaminated.
  • Check your water tap. If you have water pressure, fill up your bathtub or sink. This water can be used for cleaning, washing, etc.
  • If water is contaminated, purify water before drinking by bringing it to a boil for at least five minutes.
  • Turn the water heater thermostat to the “vacation” setting so you can draw room-temperature water from it.

To Disinfect Water in an Emergency:

  • First, filter cloudy water through a clean towel, coffee filters, pillow cases, etc., to remove any large solid materials.
  • Boil water at a rolling boil for 5 minutes.
  • Let it cool and store it in a clean, covered container or disinfect water using only regular household liquid bleach that contains 5.25% sodium hypochlorite.
  • Do not use scented bleaches, color safe bleaches or bleaches with added cleaners
  • Add plain bleach to water with an eyedropper. Recommended amounts are in the table below. If you don’t know the strength, use 10 drops per quart.
Available ChlorineDrops per QuartDrops per GallonDrops per Liter
1% 10 drops 40 drops 10 drops
4-6% 2 drops 8 drops 2 drops
7-10% 1 drop 4 drops 1 drop
  • Thoroughly stir the treated water and allow it to stand for 30 minutes before using. A slight chlorine odor should be detectable in the water. If it is not, repeat the dosage and let it stand another 15 minutes before using. Treated water may have a slight chlorine taste, but this is additional evidence of safety.
  • Since liquid chlorine bleach loses strength over time, only fresh bleach should be used for water disinfection. For bleach that is 1 to 2 years old, the dosage should be doubled. Bleach older than two years should not be used unless absolutely necessary because of uncertainty as to how much the active ingredients may have deteriorated. Bleach loses strength over time, only fresh bleach should be used for water disinfection.

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