What to Check in Your Plumbing After an Earthquake in California

Published by Clément Lacaille, Tech-Bharat · Updated September 7, 2026 · How we research

The shaking stops, and the plumbing in your house is usually not the first thing on your mind — but it's often the first thing that can hurt you if it's damaged. Broken gas lines and toppled water heaters are two of the most common sources of injury and property loss after a California earthquake, and both are things a homeowner can check safely in the first few minutes, before deciding whether to call a plumber, the gas utility, or nobody at all. Here's the order to check things in, and why that order matters.

Check for gas before you check anything else

Before you look at a single pipe, use your nose and your ears. If you smell gas — even faintly — or hear a hissing sound near an appliance or the gas meter, don't investigate further and don't flip any light switches. Get everyone outside, and if you know where your gas meter is and can reach it safely, shut off the gas there. Do not try to relight a pilot light or restore gas service yourself afterward; that's a job for the utility or a licensed plumber, both because it requires purging air from the line safely and because a utility crew typically needs to inspect before service is restored anyway. If you've already had an automatic seismic gas shutoff valve installed, it should have done this for you the moment the shaking hit a threshold — our earthquake gas shutoff valve guide covers what those devices cost and where California requires them.

Then look at the water heater

A water heater is a tall, heavy, top-weighted appliance sitting on a small footprint, which makes it one of the most earthquake-vulnerable fixtures in an ordinary house. Check whether it has shifted, tipped, or pulled away from the wall, and look at the pipe connections at the top for cracks, kinks, or water seeping out. California code has required seismic strapping on water heaters for decades specifically because an unstrapped tank can fall over, sheer its gas or water connections, and start a leak or a fire in one motion — see our water heater strapping guide for the strapping requirements and what it costs to bring an older, unstrapped tank up to code. If the tank is upright and dry, gently check that the flue (on a gas water heater) is still properly connected — a flue that's knocked loose can vent combustion gases into the house instead of outside, and it isn't always obvious from a quick glance.

Walk your water lines for what doesn't show up right away

Not every quake-caused pipe problem announces itself immediately. Watch your water meter: if it keeps spinning after you've made sure every fixture in the house is off, that's a sign of a leak somewhere in the line, even if you can't see water yet. Check under sinks, behind the washing machine, and around any exposed supply lines for new drips, since a joint that was already a little worn can crack under lateral movement without failing completely at first. Rigid, unbraced connections are the most common failure point — flexible braided connectors at the water heater, washing machine, and gas appliances are far less likely to shear than rigid pipe, which is part of why they're now standard practice rather than a nice-to-have.

The sewer lateral is the one that hides longest

Ground shaking can offset or crack the underground sewer lateral running from your house to the street, and on an older home with a cast-iron or Orangeburg lateral, that pipe is often brittle enough to shear at a joint rather than flex with the soil. The catch is that a cracked lateral frequently doesn't back up right away — it shows up as a slow drain, a gurgling toilet, or a damp patch in the yard days or weeks later, once soil and roots have had time to work into the crack. If drains that ran fine before the quake start acting up in the following weeks, that's worth a camera inspection rather than another bottle of drain cleaner; see our guide on sewer line sag and belly repair for what a shifted lateral typically costs to fix once it's confirmed.

Why the order matters: what actually happens after a big quake

This isn't a hypothetical ordering. When researchers reconstructed what happened in the hours after the 1994 Northridge earthquake, they counted roughly 110 earthquake-related fires between 4:31 a.m. and midnight that day — and gas-fed ignitions, from broken lines and appliances rather than downed power lines or anything else, accounted for close to half of them (Scawthorn, Cowell & Borden, Fire-Related Aspects of the Northridge Earthquake, NIST GCR 98-743, 1998). That's the specific reason gas checks come before anything else on this list, and why California utilities and building departments have spent the decades since pushing flexible connectors, water heater strapping, and automatic shutoff valves as standard practice rather than optional upgrades.

What to check yourself vs. what to leave to a professional

Visual checks — smelling for gas, looking at the water heater, watching the meter, noticing new leaks — are safe for any homeowner to do. What isn't a do-it-yourself job: relighting pilots or restoring gas after a shutoff, straightening or re-strapping a tipped water heater, and diagnosing a suspected sewer lateral crack, which needs a camera to confirm rather than a guess. If your water meter won't stop spinning, if a water heater has moved, or if CSST gas line flexibility at the meter and appliances looks questionable, that's worth a same-day call rather than a wait-and-see — our CSST gas line guide covers what proper bonding and connections should look like. A leak-detection visit to pin down a hidden line problem typically runs in the low hundreds of dollars for straightforward cases, as covered in our leak detection cost guide, and it's a lot cheaper than water damage that goes unnoticed for a week.

The bottom line

Gas first, water heater second, then the rest of the lines — that order isn't arbitrary, it's what the actual damage pattern from past California earthquakes looks like. If anything on this list gives you pause, especially a gas smell, a tipped water heater, or drains that started misbehaving after the ground stopped moving, request a free quote and a local licensed plumber can inspect and fix it before a minor quake-related crack turns into a bigger repair.

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