You walk into the garage or utility closet and catch a whiff of rotten eggs near your water heater. That smell is mercaptan — an additive that gas companies put in natural gas so you can detect leaks. If your water heater smells like gas, you need to take it seriously. Here's what Central Texas homeowners should know.
Step 1: What to Do Right Now
If the smell is strong or you hear hissing: Leave the house immediately. Don't flip any light switches, use your phone, or start your car in the garage — any spark can ignite gas. Once you're outside and at a safe distance, call 911 and your gas utility company (Atmos Energy for most of Central Texas). Do not re-enter until a professional clears the home.
If the smell is faint: Turn off the gas valve on your water heater. It's usually a lever or knob on the gas line feeding into the unit — turn it perpendicular to the pipe (crossways) to shut it off. Open windows and doors to ventilate the area. Then call a licensed plumber to inspect the unit before you use it again.
Common Causes of Gas Smell Near a Water Heater
Loose or damaged gas line fitting. Over time, the threaded connections where the gas line meets your water heater can loosen from vibration or thermal expansion. Even a tiny gap allows gas to seep out. A plumber can test connections with a gas leak detector or soapy water (bubbles indicate a leak) and re-tighten or replace fittings.
Failed thermocouple or thermopile. The thermocouple is a safety sensor that detects whether the pilot light is lit. If it fails, the gas valve may not close properly, allowing small amounts of gas to escape. Replacing a thermocouple is a straightforward repair — typically $150–$250 including parts and labor.
Cracked heat exchanger or burner assembly. In older gas water heaters (8+ years), the burner assembly or internal components can corrode or crack. This can cause incomplete combustion, which produces a gas-like smell even when the connections are tight. If the burner assembly is damaged, replacement of the water heater is usually the most cost-effective solution.
Pilot light keeps going out. If your pilot light won't stay lit, unburned gas can accumulate briefly each time it goes out. This is a symptom — not a cause — and usually points back to a bad thermocouple, a dirty pilot tube, or insufficient ventilation around the unit.
Sediment buildup. In Central Texas, our water is hard. Mineral sediment builds up in the bottom of tank water heaters over time. This sediment can cause the burner to overheat, damage components, and produce sulfur-like odors. Annual flushing is the best prevention.
Gas Smell vs. Sulfur Smell — Know the Difference
Not every "rotten egg" smell is a gas leak. If the smell is strongest when you run hot water (not near the unit itself), the issue is likely hydrogen sulfide in your water supply — not a gas leak. This is common in Central Texas homes with well water or areas with high mineral content.
The fix is usually replacing the anode rod in your water heater (the sacrificial rod that prevents tank corrosion) with an aluminum or powered anode rod. A water treatment system can also address the root cause.
Quick test: Run only the hot water at a faucet away from the water heater. If you smell rotten eggs at the faucet, it's your water. If the smell is only near the water heater when it's running, it's more likely a gas issue.
When to Replace vs. Repair
Repair if: the unit is under 8 years old, the issue is a thermocouple, gas fitting, or pilot tube, and the tank itself shows no signs of corrosion or leaking.
Replace if: the unit is over 10 years old, you're seeing rust-colored water from the hot side, there are signs of corrosion on the tank or burner, or the unit has had multiple repairs in the past two years. A new 50-gallon gas water heater installed typically runs $1,200–$2,000 in Central Texas.
Why This Matters in Central Texas
Our region's hard water accelerates sediment buildup and anode rod deterioration. Homes in Taylor, Rockdale, and Giddings often have well water with high mineral content, making regular water heater maintenance especially important. The extreme heat in summer also means your water heater works harder when incoming water temperatures are higher.
At Kimco Plumbing & Air, we serve 21 communities across seven Central Texas counties — including Taylor, Thrall, Coupland, Thorndale, Rockdale, Cameron, Milano, Lexington, Giddings, Ledbetter, Lincoln, Elgin, Bastrop, Smithville, McDade, Paige, Manor, Pflugerville, Cedar Creek, Caldwell, and Round Top. Whether you need an emergency gas leak inspection or a routine water heater flush, we're a local call away.
Bottom Line
A gas smell near your water heater is never something to ignore. Even if it turns out to be a minor fitting issue, the risk of undetected gas accumulation is too high to take chances. Shut off the gas, ventilate the area, and call a licensed plumber. At Kimco, we offer flat-rate pricing on water heater diagnostics and repairs — no surprise charges, no overtime fees.