Support for LAist comes from
True LA stories, powered by you
Stay Connected
Climate and Environment
How To Not Get Life-Threatening Diarrhea After A Major Earthquake
The guide on water preparedness and safety after an earthquake.
A stainless steel teapot blows out steam on an outdoor burner
(Damnikia on Unsplash)
(Damnikia on Unsplash)
LAist relies on reader support, not paywalls.
The Big One: Your Survival Guide

  • Now we're teaming up with our friends at the L.A. Times to push Southern Californians to get ready. Join us for a virtual event covering the basics of quake survival on June 24. We've also gathered the best of our coverage in a no-nonsense guide to getting ready. No more excuses. Let's do this.

A big earthquake is coming to Los Angeles. When it hits along the southern San Andreas fault there will be and, very likely, a lack of clean water. Pipes will break, and contaminants like chemicals, bacteria, viruses and parasites could enter the water supply. It's likely that L.A. and surrounding areas could be issued any number of water advisories, including a "boil water" warning.

We spent months researching this and other post-quake possibilities for our podcast, The Big One: Survival Guide.

Below are some things we've learned from experts about how to make sure your water is clean, and the different kinds of water advisories you might experience.

Support for LAist comes from

The "Do Not Use" Water Advisory

This is the red alert of water warnings.

It means exactly what it sounds like it means.

Do. Not. Use. Water. That. Comes. From. A. Pipe.

Don't use it for drinking.

Support for LAist comes from

Don't use it for showering.

Don't use it for flushing toilets.

Don't use it to hose things off.



Support for LAist comes from




A resident fills a water jug on January 18, 1994, at one of many water lines set up in the area to assist victims of the Northridge earthquake. Local authorities warned residents not to drink tap water after the quake broke many water mains in the area.
(Chris Wilkins/Getty Images

The "Do Not Drink" Water Advisory

Support for LAist comes from

This means that even if you filter or purify the water you still should not drink it. You can, however, safely shower or wash your car or whatnot.

The "Boil Water" Advisory

This is most likely the warning you'd experience, and it means you should boil water before you drink it. L.A. could be under such an advisory for more than a year after a major earthquake.

180 Degrees

Important fact: if you heat up certain bacteria, viruses and parasites to 180 degrees Fahrenheit you render them inactive, aka not gonna getcha sick.

Water boils at 212 degrees, which, yes, we know is much hotter than you need. But, since most people don't keep cooking thermometers at the ready, bringing water to a boil gives you a visual cue that the water has reached the necessary temperature to inactivate those little suckers.

And If I Don't Boil?

Well, diarrhea. The difficult-to-control-and-could-kill-you kind. Bacteria, viruses and even parasites could slither down your throat and make you very ill. There could also be chemicals or other contaminants in that water.

I Have A Brita

Super cool. But it won't save you from bacteria or parasites. Home filters do a great job at doing what they are made for — filtering minerals, some chemicals, and making water taste and smell better. But in a situation where there might be sewage leaking into your water, go ahead and boil it first.

What If I Don't Have A Way To Boil My Water?


You Want Me To Put Bleach In My Water?

No, I do not want that. But it is an option. Consider it your next best option to boiling water. If it comes down to it, you can kill a lot of bacteria by adding five (5) drops of liquid chlorine bleach into a gallon of water in a clean container and letting it sit for at least 60 minutes before drinking it. Do not use bleach that is scented or splash free. Please be careful not to use too much.

An image of a water purification chart that explains how to use bleach if the water is clear or cloudy.
( Source: Centers for Disease Control and Prevention)

Can I Drink Water From A Swimming Pool?

Think about pool water the way you think about other standing water. Like puddles. If you wouldn't drink puddle water, don't drink pool water. Even though pools have cleaning systems and, often times, chlorine, the water is not considered filtered to the level of safe drinking water.

How Much Packaged Water Do I Need?

You should keep no less than three days of drinking water on hand at your home. That calculates to one gallon per person (and animal) per day.


What are you curious about when it comes to earthquakes? What questions do you have about how to survive the Big One?