Plumbing

Why Is My Water Heater Not Working?

The short answer: No hot water at all usually means a tripped breaker (electric) or a pilot light that's gone out (gas). Check those first — they're the two easiest fixes. If hot water runs out fast, sediment buildup or a failing heating element is likely. If water is lukewarm, the thermostat may need adjusting (should be 120°F). If you hear popping or rumbling, sediment has hardened on the bottom — flush the tank or start planning a replacement.

Written by Solomon, former HVAC/plumbing field technician with thousands of residential service calls in NW Florida

Quick Diagnosis: What's Happening?

Symptom	Most Likely Cause	DIY?
No hot water at all	Tripped breaker or pilot light out	Yes
Hot water runs out quickly	Sediment, bad element, or undersized tank	Partial
Water is lukewarm	Thermostat set too low or element failing	Yes
Popping or rumbling sounds	Sediment buildup	Yes (flush)
Water leaking from tank	Corrosion or failed fitting	Call a pro
Smells like rotten eggs	Anode rod reaction with bacteria	Replace rod
T&P valve discharging water	Excessive pressure or temperature	Call a pro

No Hot Water at All

Electric Water Heater

Step 1: Check the breaker. Go to your electrical panel and look for the breaker labeled "Water Heater" or "WH." If it's in the middle position (tripped), flip it all the way OFF, then back ON.

Step 2: Check the reset button. Most electric water heaters have a red reset button on the upper thermostat (behind the access panel on the front of the tank). Press it. If it clicks, the high-limit switch had tripped — usually because of a thermostat or element failure.

Step 3: If the breaker trips again immediately — you have a short circuit. Don't keep resetting it. Call an electrician or plumber.

Field Tip: If the reset button trips repeatedly, one of the heating elements has likely failed and is grounding out. This is a $20 part but involves draining the tank and working with 240V wiring. If you're not comfortable with electrical work, call a professional.

Gas Water Heater

Step 1: Check the pilot light. Look at the small window near the bottom of the tank. You should see a small blue flame. If it's out, follow the relighting instructions on the tank's label.

Step 2: Make sure the gas valve is on. The gas valve near the water heater should be parallel to the gas line (perpendicular = off).

Step 3: Check the thermocouple. If the pilot lights but won't stay lit, the thermocouple (a safety sensor near the pilot) is likely bad. This is a $10-$15 part.

Safety Warning: If you smell gas, don't light anything. Turn off the gas valve, ventilate the area, leave the house, and call the gas company from outside. A gas leak is an emergency.

Hot Water Runs Out Too Fast

If you used to get 20 minutes of hot water and now you get 10, the most common causes are:

Sediment buildup — minerals have accumulated at the bottom of the tank, reducing the effective volume and insulating the bottom element. Flush the tank.

Failed lower heating element (electric) — electric water heaters have two elements. The lower one heats the bulk of the water. If it fails, you'll get some hot water from the upper element but it runs out quickly. Replace the element ($15-$25 part).

Dip tube failure — the dip tube directs cold inlet water to the bottom of the tank. If it breaks, cold water mixes with hot water at the top, giving you lukewarm output. The tank may need to be replaced depending on the model.

Water Is Lukewarm

Check the thermostat setting. On an electric heater, it's behind the access panels (usually two — upper and lower). On a gas heater, it's a dial on the gas valve. Set it to 120°F. Lower than that and you'll feel it's not hot enough. Higher than 140°F and you risk scalding.

On electric heaters, the upper element or thermostat may be failing. The upper element/thermostat controls the initial heating. If it's not working, the lower element does all the work — and it can't keep up.

Strange Noises

Popping, crackling, or rumbling — sediment has hardened on the bottom of the tank. Water trapped under the sediment boils and creates these sounds. Flush the tank. If it's been years since the last flush, the sediment may be too hardite to remove — that means the tank is nearing end of life.

Screeching or whining — a valve (usually the T&P valve or inlet valve) is partially open and water is being forced through a narrow gap. Check all valves.

Rotten Egg Smell

A sulfur or rotten egg smell from hot water only (not cold) is usually a reaction between the magnesium anode rod and sulfate-reducing bacteria in the water. This is more common with well water.

Fixes:

Flush the tank with hydrogen peroxide (a few pints in the tank)
Replace the magnesium anode rod with an aluminum/zinc anode rod ($25-$40)
For persistent cases, install a powered anode rod ($90-$150) that eliminates the reaction entirely

When to Call a Professional

Gas smell (leave and call the gas company)
T&P relief valve continuously discharging water (dangerous pressure issue)
Water leaking from the tank body (not fittings)
Breaker trips repeatedly after resetting
You're not comfortable working with electricity or gas
The water heater is over 10 years old and having multiple issues (replacement likely makes more sense)

Expect to pay: $100-$200 for a service call, $150-$350 for element replacement, $200-$400 for thermostat/thermocouple replacement.

Florida Factor: In NW Florida, many homes have water heaters in enclosed closets with poor ventilation. Gas water heaters in these spaces need adequate combustion air. If your gas water heater keeps shutting off, check that the closet has proper ventilation openings — building code typically requires two openings.

This answer covers the basics, but every home is different. Kept's AI Advisor knows your systems — their age, your climate, your maintenance history — and can give you guidance specific to your situation.

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