Gas Leak Safety in California: What to Do and Who Can Fix It
Natural gas incidents are rare, but when they happen they are unforgiving — which is why the rules around gas leaks are stricter and simpler than for any other plumbing problem. This guide covers the exact protocol for a suspected leak, who is legally allowed to work on gas lines in California, and the earthquake shutoff valve requirements that apply in parts of the state.
The rotten egg protocol
Natural gas is odorless; utilities add mercaptan so leaks smell like rotten eggs or sulfur. If you notice that smell — or hear hissing near a gas appliance, or see dirt blowing from the ground near your gas line — do this, in order:
- Do not flip any switches, light anything, use a phone indoors, ring a doorbell, or start a car in an attached garage. A single spark can ignite accumulated gas.
- Leave immediately. Get everyone, including pets, out of the building. Leave the door open behind you if it's already open — but don't operate anything electrical to open it.
- Call from outside. Once you're a safe distance away, call 911 or your gas utility's emergency line (PG&E, SoCalGas, or SDG&E depending on where you live). Utilities respond to leak calls around the clock at no charge.
- Don't go back in until the utility or fire department says it's safe.
If the smell is faint and clearly coming from a pilot light that has blown out, you can ventilate and relight per the appliance instructions — but when in doubt, treat it as a leak. No one has ever regretted being too cautious with gas.
Who can legally work on gas lines
This is not a DIY category, and it's not a handyman category either. In California, gas piping work must be performed by an appropriately licensed contractor — typically a C-36 plumbing contractor licensed by the Contractors State License Board (CSLB) — and most jurisdictions require a permit and inspection for new or modified gas lines. Unpermitted gas work can void insurance coverage and creates real problems at resale. You can verify any contractor's license status free on the CSLB website before hiring.
Typical scenarios that require a licensed pro: running a new line to a range, dryer, fire pit or outdoor kitchen; repairing corroded or damaged piping; moving a meter connection; and pressure-testing after an earthquake or renovation. Expect gas line work to run roughly $300–$800 for a simple appliance connection and $500–$2,500+ for new line runs, depending on length, trenching, and permits. In dense markets like San Francisco and Los Angeles, permit and access costs push toward the top of those ranges.
Earthquake shutoff valves: sometimes required, always smart
A seismic gas shutoff valve automatically closes your gas supply when it senses strong shaking, preventing the post-earthquake fires that historically cause much of the damage in major quakes. Some California cities — including Los Angeles — require an automatic gas shutoff valve to be installed when a property is sold or significantly renovated. Requirements vary by city, so check your local ordinance or ask your plumber. Even where they're optional, installation typically costs a few hundred dollars plus the valve and is one of the highest-value seismic upgrades available. Our guide to earthquake plumbing preparedness covers the full checklist, including water heater strapping and flexible connectors.
Know your shutoffs before you need them
Every adult in the house should know where the main gas shutoff is (at the meter — a quarter turn of the valve with a wrench closes it) and where the appliance shutoffs are. Keep a wrench zip-tied near the meter. One caution: if you shut off gas at the meter, only the utility should turn it back on, because relighting requires checking every pilot and appliance.
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