What to Check When a Hot Water Heater Stops Working

If your hot water heater suddenly stops producing hot water, it’s not just an inconvenience-it’s a daily disruption. Breakfast showers, laundry, dishes-all grind to a halt. Before you call a plumber or panic about a replacement, there are simple checks you can do yourself. Most of the time, the issue isn’t a broken tank. It’s something small, fixable, and often under $50 to fix.

Check the power supply first

Electric water heaters rely on electricity to heat water. If the power goes out, even briefly, the heater won’t turn back on unless you manually reset it. Start by checking your home’s circuit breaker panel. Look for the breaker labeled water heater, hot water, or something similar. If it’s flipped to the middle or off position, turn it all the way off, then back on. That’s it.

Some older models have a separate reset button on the thermostat, usually red and located behind a small panel. Press it once. If it clicks, you’ve reset the high-limit switch. That switch trips if the water gets too hot-often because of a faulty thermostat or sediment buildup. If the button pops out again after you reset it, there’s a deeper problem.

Don’t assume the breaker is fine just because it looks on. Test it with a multimeter if you have one. If you don’t, try plugging a lamp into the same outlet (if your heater is plugged in) or check other circuits nearby. A tripped GFCI outlet in the garage or basement can also cut power to the water heater. Look for a small reset button on outlets near the heater.

Inspect the thermostat settings

Thermostats can drift over time. Maybe someone turned it down during summer, or the dial got bumped. Most water heaters are set to 120°F (49°C)-the recommended safety temperature. If it’s set below 110°F, you won’t get hot enough water. If it’s set above 140°F, you risk scalding and higher energy bills.

For electric models, there are two thermostats-one on top, one on bottom. Both must be set to the same temperature. Turn off the power before removing the access panels. Use a flathead screwdriver to adjust the dial. Don’t guess-use a thermometer to test water temperature at the tap after waiting 30 minutes.

Gas water heaters have a single dial on the bottom of the tank, near the gas valve. Turn it from “Pilot” to “Hot” or “Medium.” If it was on “Pilot,” that’s likely your issue. The pilot light went out. But don’t relight it yet-read the next section.

Check the pilot light (gas heaters only)

If you have a gas water heater and no hot water, the pilot light may be out. This is common after a power outage, strong draft, or gas supply interruption. First, smell for gas. If you smell rotten eggs, leave immediately and call your gas company. No smell? Proceed.

Follow the instructions on the tank’s label. Usually, you turn the gas valve to “Off,” wait five minutes, then switch to “Pilot.” Press and hold the pilot button while lighting it with a long match or lighter. Keep holding for 30 seconds after the flame catches. Then turn the knob to “On.” If the flame goes out again, the thermocouple is likely faulty.

The thermocouple is a thin metal rod next to the pilot flame. It senses heat and tells the gas valve to stay open. If it’s dirty, bent, or broken, the gas shuts off. Clean it with fine sandpaper. If that doesn’t work, replace it. They cost under $20 and are easy to swap.

Look for sediment buildup

Sediment-minerals like calcium and magnesium-sinks to the bottom of the tank over time. It acts like insulation, trapping heat and preventing it from reaching the water. That means longer heating times, louder popping noises, and eventually, no hot water.

Draining a tank is one of the most overlooked maintenance tasks. Do it once a year. Turn off the power or gas. Close the cold water inlet valve. Attach a garden hose to the drain valve at the bottom. Open the valve and let water drain into a bucket or outside. Open a hot water faucet upstairs to let air in. Drain until the water runs clear. This can restore performance instantly.

If you live in an area with hard water, sediment builds up faster. Installing a water softener helps, but draining the tank still matters. Even if your heater is 10 years old, a good flush can add years to its life.

Test the heating elements (electric models)

Electric water heaters have two heating elements-one at the top, one at the bottom. If the top element fails, you get a little warm water for a few minutes, then cold. If the bottom fails, you get lukewarm water that runs out fast.

To test them, turn off the power. Remove the access panels and insulation. Use a multimeter set to ohms (Ω). Touch one probe to each terminal on the element. A good element reads between 10 and 16 ohms. If it reads zero or infinity, it’s dead. Replace it. Elements cost $20-$40 and take 30 minutes to swap. Don’t forget to drain the tank first.

Also check the high-limit switch. If it’s tripped, the element won’t turn on. Reset it. If it trips again, the thermostat is likely faulty. Replace both thermostats together-they’re usually sold as a pair.

Check for leaks and tank corrosion

If you see water pooling around the base of the heater, or rust on the tank or pipes, that’s a red flag. A small drip from a valve or pipe is fixable. But if the tank itself is leaking, it’s done. Water heaters don’t get patched-they get replaced.

Look for rust streaks running down the sides. Tap the tank with a screwdriver. If it sounds hollow or the metal flakes off, corrosion has eaten through. Most tanks last 8-12 years. If yours is older than 10 and leaking, replacement is cheaper than repeated repairs.

Also check the pressure relief valve. It’s on the top or side of the tank, with a pipe running down to the floor. If it’s leaking constantly, the pressure inside is too high. Test it by lifting the lever. Water should flow briefly, then stop. If it drips after, replace the valve. They cost $15 and are easy to install.

Consider the age and type of your heater

Water heaters don’t just wear out-they become inefficient. A 15-year-old tank-style heater uses 30% more energy than a new one. If you’re replacing parts often, or your energy bill is climbing, it’s time to upgrade.

Modern options include tankless heaters, heat pump water heaters, and hybrid models. Tankless units provide endless hot water but need higher gas lines or electrical upgrades. Heat pump models cut energy use by half but need space and warm air to work well.

If you’re not ready to replace it, focus on fixing what’s broken. But if you’re spending more than $300 on repairs in a year, replacement is the smarter move.

When to call a professional

You don’t need to be a plumber to fix most water heater issues. But some things require a licensed pro:

• Gas leaks or strong gas odor
• Electrical wiring that’s frayed or outdated
• Replacing the entire tank or installing a new model
• Heater is under warranty-you don’t want to void it
• You’re uncomfortable working with gas, electricity, or high-pressure water

Most repairs-resetting breakers, replacing elements, cleaning sediment-can be done in under an hour with basic tools. Save the pro for the big stuff.

Next steps: What to do now

Start with the easiest checks: power, thermostat, pilot light. Those take five minutes. If you’re still cold, drain the tank. That’s the next most common fix. If that doesn’t help, test the elements or call a pro.

Keep a notebook. Write down the model number, age, and any repairs you do. That helps if you need to call someone later. Take a photo of the thermostat settings before you adjust them. It’s easy to forget what you changed.

Most water heater problems are fixable without replacing the whole unit. You don’t need to live without hot water. Just take it step by step. You’ve got this.