If you’re using a gas-fired water heater, you might have noticed the tiny blue flame known as the pilot light. Its purpose is to produce the flame required to ignite the gas coming out of the burner. When your water heater’s pilot light won’t ignite, it can’t heat the water, which means you’re in for a freezing shower.

The good news is that troubleshooting this common household problem is simple. It’s also important to fix it as soon as possible to make sure that no gas is released into your home, which could potentially cause an explosion.

4 Common Reasons Your Water Heater Won’t Ignite

Dirty Pilot Tube

Dirt, dust, and debris can block the flow of gas from the pilot tube. This means that the pilot light isn’t receiving enough fuel to fully ignite. Thankfully, fixing this issue is easy -- all you need is a long needle and a bit of patience. Gently poke the needle into the pilot hole and remove any debris. This may take several tries depending on the amount of debris that has accumulated. To check if you’ve completely gotten rid of all the debris, simply “turn on” the pilot and see if it produces a bright, blue flame.

Faulty Thermocouple

Depending on your type of water heater, it may have a thermocouple (older water heaters) or a flame sensor (newer water heaters). The thermocouple is the device that senses heat in the pilot light and triggers the flow of gas into the burner. When it detects that the pilot light hasn’t been ignited, it automatically cuts the gas as a safety precaution. Sometimes, debris gets in the way and can interfere with its ability to detect the ignition of the pilot light. While you can take the DIY route, you’re better off seeking the help of professional HVAC technicians.

Broken Gas Control Valve

If neither cleaning the pilot light nor replacing the thermocouple helps ignite your water heater, the problem might be with the gas control valve. The gas control valve does exactly what you think it does: it regulates the amount and pressure of gas that flows into your unit. Too much could cause fires and explosions, while too little won’t produce the right amount of gas needed to function. Fixing this requires the help of a professional technician as it involves disconnecting the gas lines and installing a new valve.

Damaged Gas Burner

In extremely old water heaters, the gas burner inside the burner chamber may have cracked. This is expected after years of wear and tear. The only way to fix this is by replacing the gas burner, but it may be more economical to replace the entire unit instead. A damaged gas burner is a sign that your water heater is on its last legs.

When All Else Fails

If you’ve followed the steps above and your water heater still won’t ignite, the problem may be more serious and probably requires the assistance of professional appliance technicians. In rare cases, you might need to replace the entire water heater, but often the problem can be fixed with the right tools and skills.

**Note: It can be very dangerous to fix your water heater yourself. You should always call your HVAC professional to have it repaired safely.