Water heater smells like gas: what to do right now
A gas smell near a water heater is an emergency until proven otherwise. Here's what to do in the first minute, what not to touch, and what happens after.
Updated October 21, 2026 · 5 min read · By the Heater Doctor team
Short answer
Leave the house now. Don't flip switches, use phones inside or try to find the leak. Once you're outside and away from the building, call 911 or your gas company's emergency line. Don't go back in until they say it's safe. After the gas company makes the area safe, a plumber can repair the leaking connector or valve.
Do this first
National Grid's guidance is typical of what gas utilities tell customers:
- Leave the building immediately. Leave windows and doors as they are.
- Don't touch electrical or light switches, doorbells, phones, appliances or thermostats. Don't plug in or unplug anything. Any of these can make a spark.
- Put out open flames, like candles, if you can do it on your way out.
- Call from outside, at a safe distance: 911 or your gas company. National Grid says not to assume someone else has already called.
Why gas smells like rotten eggs
Natural gas has no smell of its own. National Grid says it adds a sulfur-smelling chemical called mercaptan so leaks can be noticed right away. If the smell is in the air around the heater, treat it as gas. If it's only in your hot water, that's usually the anode rod (see hot water smells like rotten eggs).
Gas company emergency numbers in our areas
| Utility | Emergency line | Example town |
|---|---|---|
| UGI (Pennsylvania) | 800-276-2722 | Lebanon |
| Columbia Gas (Pennsylvania) | 1-888-460-4332 | York |
| Xcel Energy (Colorado) | 800-895-2999 | Erie |
| Atmos Energy (Colorado) | 866-322-8667 | Evans |
| Black Hills Energy (Colorado) | 888-890-5554 | Frederick |
| Intermountain Gas (Idaho) | 800-548-3679 | Eagle |
| Avista (Idaho) | 800-227-9187 | Post Falls |
| National Grid (Massachusetts) | 1-800-233-5325 | Braintree |
Eversource gas customers in Massachusetts should call 911 or Eversource's gas emergency line. When in doubt, call 911.
Other gas emergencies around a water heater
National Grid also treats these as emergencies: an abnormally high or low flame, gas that can't be shut off to an appliance, and a continuous flow of water leaking from a gas water heater. Call the same numbers.
Carbon monoxide has no smell
A gas smell is a leak warning. Carbon monoxide from a badly vented heater gives no warning at all. That's why CO alarms matter in any home with gas appliances. The CPSC doesn't recommend putting them in kitchens or right above fuel-burning appliances. Follow the alarm maker's instructions on where to mount them, and if one sounds, get everyone outside and call 911.
After the emergency
The gas company finds and stops the leak, and may shut off and tag the appliance or meter. Don't relight the heater or turn the gas back on yourself. A plumber can replace a leaking flex connector, fitting or gas control valve, and the utility or plumber relights it once it's safe.
Rather have a plumber look at it?
Call and describe what's happening. We'll get a plumber out to diagnose and fix it.
Call for service(858) 465-8561Local pages mentioned
Related water heater services
Common questions
Is a faint gas smell near the water heater normal?
No. Any gas smell in the air should be treated as a leak. Leave and call from outside.
Can I just turn off the gas valve at the water heater?
Don't stay inside to do it. Utilities tell customers to leave first and call from outside. Let the gas company decide what to shut off.
Who fixes a gas leak at the water heater?
The gas company handles the emergency and makes it safe. A licensed plumber or gas fitter then repairs the connector, fitting or valve on your side of the meter.
Sources
- National Grid, report a gas emergency
- National Grid, Gas Emergencies
- U.S. Consumer Product Safety Commission, Carbon Monoxide Fact Sheet
General information only. Gas, electrical and pressure work can be dangerous; when in doubt, call a licensed professional.
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