Emergency Information from the San Francisco Public Utilities Commission
Drinking Water After An Earthquake, Flood or other Disaster: The First 72 Hour
This web page is designed to help you prepare an emergency source of drinking water in case of an earthquake, flood or other emergency.
The Kobe, Northridge and Loma Prieta earthquakes showed that a strong quake can impact or severely limit the delivery of water to homes and businesses. It is likely that it could take 72 hours or more after a serious quake to get drinking water to the community at large.
These are recommendations to help you prepare for an earthquake or other emergency. Be sure to share this information with your family and friends.
How might an earthquake impact the availability of safe drinking water?
Earthquakes can result in major infrastructure damage and utility service disruptions. Water deliveries to homes and businesses could cease or be severely limited. It is impossible to know how long water service will be impacted. However, it is likely that is could take several days (or more) to have the water and utility systems repaired to routine operating conditions.
In a serious earthquake or other disaster, how long will service be disrupted and/or water quality problems continue?
It is not possible to predict how long water service will be impacted. However, it is likely that it could take several days (or more) after a serious quake to restore the water distribution system back to "normal" operating conditions.
Should I store drinking water in case of emergencies?
Yes. You should store one gallon per day per person to last at least 72 hours. If you have pets, you might consider storing additional water for their needs as well.
How will I know if my drinking water is safe to drink after a disaster? Listen to information over the emergency broadcast system on the radio and TV (or other official communications) and carefully follow their directives. For example, you may be instructed to disinfect or boil your water before drinking. Information about the location of emergency supplies of drinking water may be announced. (As you can see, having a portable radio with extra batteries is extremely important!!)
In an emergency where the drinking water may be unsafe, what can I do to make it safe to consume?
Boiling water for one minute (after it reaches boiling) is the most effective way you can self treat water. Before boiling, strain it through a clean cloth to remove any sediment, floating matter or glass. Of course, great care should be taken to prevent burns or fires when boiling water.
In the above situation what should I do if I cannot boil the water?
Boiling water should be your first choice. You can, however, disinfect water with common household liquid chlorine bleach. This will kill bacteria in the water. Add eight drops of bleach per gallon with an eyedropper for clear water and 16 drops per gallon if the water is cloudy. Shake and let stand for 30 minutes before using. A slight chlorine odor should be detectable in the water. If not, repeat the dosage and let stand for additional 15 minutes.
What alternative sources of drinking water can I use in an emergency?
Water from available ice cubes, canned vegetables and commercial bottled water can be consumed.
How should I store emergency drinking water?
Storing commercial bottled water is probably the best way for you to have water available in the event of an emergency. Emergency drinking water should be stored in a cool, dry place, away from sunlight. Though commercial bottled water should be your first choice, strong plastic containers with tight fitting caps can be used to store drinking water. Do not store water in glass containers because they can break during an earthquake. Also, avoid using plastic milk bottles as they disintegrate over time. Sterilizing the containers and disinfecting the water after filling (as described earlier) can slow down possible bacterial growth that can occur in stored water. Make sure to label and date the containers. To be safe, stored emergency water (including commercial bottled water) should be replaced every three to four months. Water stored longer than this period should be disinfected prior to use.
Can water from a hot water heater be used in an emergency?
Generally yes, but this water can also be contaminated and may require boiling or disinfecting before being consumed. As mentioned earlier, follow the directives of your community disaster officials regarding what is necessary; self treating your water through boiling and/or chlorine disinfecting is necessary.
Can I use water from a toilet tank, spa or pool for drinking purposes?
This water should be considered your supply of last resort. Pool or spa water should be used only if it is first boiled (disinfecting chlorine bleach is probably not an adequate safeguard by itself). As mentioned earlier, don't forget to strain the water through a piece of clean cloth before treating.