October 21, 2025
Few things are more frustrating than turning on your shower or faucet only to be met with cold water. When your water heater stops heating, it disrupts your entire household routine. The good news? Many water heater heating problems have simple causes that you can identify yourself, and some even have quick DIY fixes.
Before you panic or immediately call for emergency service, let's walk through the most common reasons why your water heater isn't heating water and what you can do about it.
Gas Water Heater Not Heating: Common Causes
If you have a gas water heater, here are the most likely culprits when it stops producing hot water:
1. Pilot Light is Out
The Problem: The pilot light is the small flame that ignites your gas burner. If it goes out, your water heater can't heat water.
How to Check: Look through the viewing window at the bottom of your water heater. You should see a small blue flame. If you don't see it, the pilot light is out.
Quick Fix: Most gas water heaters have relighting instructions on a label attached to the unit. Follow these carefully. Typically, you'll turn the gas valve to "pilot," hold down the pilot button, use the igniter button or a long lighter to ignite the flame, and then release the button after 30 seconds.
When to Call a Pro: If the pilot light won't stay lit after multiple attempts, you likely have a faulty thermocouple or gas valve that needs professional replacement.
2. Thermocouple Problems
The Problem: The thermocouple is a safety device that detects whether the pilot light is burning. If it's faulty, it will shut off the gas supply even when the pilot is lit.
Signs: Your pilot light goes out frequently, or it won't stay lit after you release the pilot button.
The Solution: Thermocouples are inexpensive parts, but replacement requires some technical knowledge. Most homeowners prefer to have a professional handle this repair.
3. Gas Supply Issues
The Problem: Your water heater isn't getting enough gas, or the gas supply is completely shut off.
How to Check: Make sure the gas valve (located on the gas line leading to your water heater) is fully open. It should be parallel to the pipe. Also check if other gas appliances in your home are working. If nothing is working, there may be a problem with your main gas line.
The Solution: If the valve was closed, open it and relight the pilot. If you suspect a broader gas supply problem, contact your gas company immediately.
Electric Water Heater Not Heating: What to Look For
Electric water heaters have different components than gas models, so the troubleshooting process is different:
1. Tripped Circuit Breaker
The Problem: This is the most common and easiest to fix. Your water heater's circuit breaker has tripped, cutting power to the unit.
How to Check: Go to your electrical panel and look for a breaker in the "off" position or somewhere between on and off. Water heaters typically use a double-pole breaker (takes up two slots).
Quick Fix: Flip the breaker all the way off, then back to the on position. If it trips again immediately, you have an electrical problem that requires professional diagnosis.
2. Faulty Heating Elements
The Problem: Electric water heaters have two heating elements (upper and lower). When one or both fail, you'll get lukewarm or no hot water.
Signs: You have some hot water but it runs out quickly (one element still working), or you have no hot water at all (both elements failed).
The Solution: Testing and replacing heating elements requires working with high-voltage electricity. This is definitely a job for a professional plumber or electrician.
3. Bad Thermostat
The Problem: The thermostat controls when the heating elements turn on and off. If it's malfunctioning, your elements won't heat the water even though they're working fine.
How to Check: Try adjusting the temperature setting on your thermostat. Electric water heaters have thermostats behind access panels on the side of the tank. The recommended setting is 120°F.
The Solution: Testing thermostats requires a multimeter and knowledge of electrical systems. Professional diagnosis is recommended.
4. Reset Button Tripped
The Problem: Electric water heaters have a high-temperature cutoff switch (reset button) that trips if the water gets too hot. This is a safety feature.
How to Check: Remove the access panel on the upper portion of your water heater. You'll see a red button. If it's popped out, it has tripped.
Quick Fix: Press the reset button. If it clicks and stays in, restore power and wait to see if the water heats. If the button trips again, you have an underlying problem (faulty thermostat or element) that needs professional attention.
Problems Affecting Both Gas and Electric Water Heaters
Some issues can affect any type of water heater:
Sediment Buildup
The Problem: Over time, minerals in your water settle at the bottom of the tank, creating an insulating layer between the heating source and the water.
Signs: Your water takes longer to heat, you hear popping or rumbling sounds, or you have reduced hot water capacity.
The Solution: Annual flushing removes sediment and maintains efficiency. If you've never flushed your tank and it's several years old, sediment may be so thick that flushing won't completely solve the problem.
Tank Size Too Small
The Problem: Your water heater is working fine, but it can't keep up with your household's hot water demand.
Signs: You run out of hot water during normal usage (like taking a shower after someone else just showered).
The Solution: This isn't actually a malfunction. You may need a larger tank or consider upgrading to a tankless water heater for unlimited hot water.
Age of Unit
The Problem: Water heaters typically last 8 to 12 years. As they age, they become less efficient and more prone to failure.
Signs: Your unit is approaching or past 10 years old, requires frequent repairs, or shows signs of rust or leaks.
The Solution: Replacement is often more cost-effective than repeated repairs on an old unit.
Safety First: When to Call a Professional
While some water heater problems have simple solutions, others require professional expertise. Call Total Mechanical Care if:
- You smell gas around your water heater
- You see water pooling around the base of the tank
- Your circuit breaker trips repeatedly
- You're uncomfortable working with gas or electrical components
- The pilot light won't stay lit after multiple attempts
- You've tried basic troubleshooting without success
- Your water heater is making loud, unusual noises
- Your unit is old and experiencing multiple problems
