Why Is My Water Heater Not Working? (7 Causes & Fixes)

No Hot Water? Let’s Fix That

Nothing ruins a morning faster than a surprise ice-cold shower. One minute you’re half-asleep, the next you’re wide awake and very unhappy with your water heater’s life choices.

Here’s the good news. Most water heater failures aren’t disasters. They’re just stubborn. We’ve been fixing San Diego’s water heaters since 1983 (back when MTV actually played music videos). In that time, we’ve learned one truth: 90% of “no hot water” emergencies come down to a handful of common issues.

This guide walks you through them. The quick checks you can do yourself, and the red flags that mean it’s time to call in the pros.

7 Reasons Your Water Heater Isn’t Heating

Pilot Light is Out (Gas Heaters)

When your gas water heater stops working, check the small window near the base. No blue flame means the pilot light went out. You might notice a faint gas odor too, especially if there’s a leak. Relight it by following the instructions printed on your unit or in the manual. Every model has slightly different steps.

If you smell gas at any point, turn off the gas valve immediately and call a plumber. Don’t try to relight it or troubleshoot further . Gas leaks are dangerous and need professional attention right away.

Sometimes the pilot light keeps going out because the thermocouple (a safety sensor) has failed. While it’s a simple part, fixing it properly requires shutting off the gas and some technical know-how.

Tripped Circuit Breaker (Electric Heaters)

Electric water heaters often stop working when their breaker trips. Check your electrical panel for a switch that’s flipped to the middle position. This is usually the water heater’s dedicated breaker. Flip it all the way off, then back on to reset it.

If the breaker trips again immediately or within a few hours, stop resetting it. This means there’s a serious problem like a short circuit, faulty wiring, or a broken heating element. Continuing to reset it could cause damage or even start an electrical fire.



For persistent breaker trips, you’ll need an electrician or plumber to diagnose the issue. It might be a problem with the heater itself, your home’s wiring, or an overloaded electrical system that needs upgrading.

Faulty Thermostat

Your water heater's thermostat controls the temperature. When it breaks, you get strange water temps. Showers turn cold fast. Or the water gets too hot. This problem creeps up slowly.

To test it, use a multimeter. First turn off the power. No reading means it's bad. Some people can do this. But water and electricity are risky.

Replacing it requires skill. Wires must connect perfectly. Temperatures need exact settings. Mistakes cause burns or damage. A pro can fix it right. They have the proper tools. It gets done safely and quickly.

Broken Heating Element (Electric Heaters)

Electric water heaters have heating elements inside. When one fails, your water won't get hot. You might get lukewarm water. Or no hot water at all.

First, turn off the power at the breaker. Safety comes first. Use a multimeter to test the element. No continuity means it's dead. Some people can replace elements themselves.

But remember these heaters hold water. Draining them takes time. The gaskets must seal perfectly. Wiring must connect just right. One mistake causes leaks or shocks. A pro can do it safely in one visit.

Sediment Buildup in Tank

San Diego's hard water leaves minerals behind. Over time, they collect in your tank. You'll hear rumbling noises. Hot water runs out faster. Your heater works harder but heats less.

Flushing helps remove this buildup. Turn off the heater first. Connect a hose to the drain valve. Let the water run until clear. This simple maintenance can help a lot.

For heavy buildup, call a pro. We use special tools to clean tanks. This prevents damage to your heater. It helps your unit last longer too. Regular flushing saves money on repairs.

Gas Valve or Supply Issues (Gas Heaters)

First check the basics. Is the gas valve turned on? It should point along the pipe. Did you pay your gas bill? Sometimes the answer is that simple.

If the valve is on and service is active, but you still get no heat, stop here. Gas line problems are different. They need special tools to fix safely.

Never try to repair gas lines yourself. Even small leaks can be dangerous. Always call a licensed plumber for gas work. We have the right training and equipment to handle it properly.

Water Heater Too Small

Your morning shower goes cold too fast. The dishwasher runs while someone showers. Suddenly, no hot water remains. These are classic signs your heater is too small.

Tank water heaters store limited hot water. More people means faster drain times. Long showers use more than short ones. Your habits may have changed since installation.

Consider upgrading to a larger tank. Or switch to a tankless system. Tankless heaters make endless hot water. We can help choose the right size. Just call for a free estimate.

When to Call a Professional Plumber

Some problems scream "call for backup." Gas smells? Sparks near your heater? Water pooling around the tank? These aren’t DIY moments—they’re "get a pro here now" emergencies.

San Diego’s hard water adds another wrinkle. That mineral buildup you’ve been ignoring? It’s quietly choking your heater’s efficiency. Professional maintenance can double its lifespan.

Don’t gamble with leaks or electrical gremlins. American Plumbing Co. fixes water heaters same-day. No upselling, no drama—just honest work. Call (619) 723-1114 today for a free estimate. We’ll stop your cold showers for good.

Keep Your Water Heater Happy

Flush your tank every year. It forces out sediment that steals heat and space. Just hook a hose to the drain valve and let it run until the water clears. Easy, but effective.

Test the pressure relief valve every six months. Lift the lever briefly—you should hear a rush of water. If nothing happens, the valve’s stuck. That’s dangerous pressure building up.

Wrap exposed pipes with insulation sleeves before winter. It stops heat loss so your heater works less. Bonus: Your energy bill shrinks too.

Water Heater FAQs

How do I reset my water heater?

Find the red reset button on the thermostat (electric models only). Press it firmly. If it trips again immediately, stop—you’ve got an electrical issue.

Why is my heater growling like a bear?

That’s sediment getting cooked at the tank’s bottom. Flushing helps, but if it’s loud, the buildup might need professional cleaning.

When should I replace my unit?

After 10 years, start saving. Old heaters waste energy and love springing leaks at 3 AM. San Diego’s hard water cuts lifespans even shorter.

Bottom Line: Know When to Call for Backup

Most water heater problems start small. A tripped breaker. A pilot light out. These you can often fix yourself. But gas leaks? Electrical shorts? Major leaks? That’s when you call the pros.

San Diego homeowners have trusted us since 1983—not just because we fix heaters fast, but because we show up honest. No scare tactics. No unnecessary upsells. Just straight talk and permanent solutions.

Don’t play guessing games with your hot water. Call (619) 723-1114 right now. We’re here 7 days a week, ready to get you back to hot showers.