Yes, water heaters can leak gas, particularly if they are gas-powered; this poses a safety risk and requires immediate inspection and repair.
Gas leaks from water heaters are rare but dangerous. A faulty connection, aging valve, or cracked heat exchanger can allow natural gas or carbon monoxide to escape. Knowing the warning signs could save your life.
How to Detect a Gas Leak from Your Water Heater
Gas companies add mercaptan to natural gas, creating a rotten egg smell. This is your first warning sign. Other red flags include:
- Hissing sounds near gas connections
- Dead plants near the water heater
- Bubbles in soapy water applied to connections
- Higher than normal gas bills
Physical Symptoms of Gas Exposure
Carbon monoxide poisoning causes:
- Headaches and dizziness
- Nausea or vomiting
- Pale skin or blisters (with direct propane contact)
- Difficulty breathing
Common Causes of Water Heater Gas Leaks
Faulty Gas Connections
Over time, the flexible gas line can degrade. The brass fittings may crack if overtightened during installation.
Failed Control Valve
The gas control valve regulates fuel flow. When it fails, gas can leak even when the heater is off. Replacement valves should match your model’s BTU rating.
Cracked Heat Exchanger
In tankless models, thermal stress can crack the heat exchanger. This allows combustion gases to mix with water vapor.
| Leak Location | Risk Level | Repair Cost |
|---|---|---|
| Gas Line Connection | High | $150-$300 |
| Control Valve | Critical | $200-$500 |
| Heat Exchanger | Extreme | $800+ (usually requires replacement) |
Emergency Steps for Suspected Gas Leaks
- Evacuate immediately – don’t turn lights on/off
- Call your gas company or 911 from outside
- Don’t re-enter until professionals declare it safe
- Have a plumber inspect all connections before restarting
Preventative Maintenance Tips
The American Gas Association recommends annual inspections. Key checks include:
- Testing gas pressure
- Inspecting venting systems
- Checking flame color (should be blue, not yellow)
Modern water heaters have safety features like flame arrestors and automatic shutoffs. However, as noted by NFPA, no system is completely foolproof against all failure modes.
When to Replace vs. Repair
Consider replacement if:
- Unit is over 10 years old
- Multiple components are failing
- You’ve had repeated leak issues
Newer models with sealed combustion chambers greatly reduce leak risks. Tankless units vent directly outside, eliminating indoor gas exposure.
