Category: Water Heater

Short answer: First decide whether the problem is the whole house or one fixture. Whole house, electric heater: check the breaker and the high-limit reset, then suspect a failed element or thermostat. Whole house, gas heater: check that the gas is on and whether the pilot or igniter is working. One fixture only: the faucet cartridge or mixing valve. If you smell gas, leave and call the gas utility from outside.

Quick diagnosis

What you notice	Most likely cause	What to check	Call a pro?
No hot water anywhere, electric heater	Tripped breaker, high-limit reset or failed element	Check the breaker	Often
No hot water anywhere, gas heater	Pilot out, gas supply off, failed thermocouple or igniter	Look at the pilot window and status light	Often
Some hot water but runs out fast	Sediment or one failed element	Listen for rumbling; note recovery time	Sometimes
Hot in the sink, not in the shower	Shower cartridge or mixing valve	Compare fixtures	Sometimes
Water heater leaking	Tank or valve problem	Look at the base and fittings	See leaking guide

Electric water heaters

A. O. Smith lists a power issue or a faulty heating element among the causes of no hot water. Check the breaker first. Many electric heaters also have a high-limit (ECO) reset button behind an access panel; it trips when the water overheats. Because those panels expose live wiring, turn the breaker off before opening them, or let a professional do it. If the reset keeps tripping, there is an underlying fault.

Gas water heaters

On gas models, A. O. Smith points to a gas supply or pilot problem. Check that the gas valve is on and look through the sight window for the pilot flame or the status light code. Follow the lighting instructions on the label exactly; never use force on the gas control. A thermocouple or gas valve that has failed is a job for a pro.

Not enough hot water

Rheem lists running out of hot water sooner than usual, longer recovery, and rumbling or popping noises as signs of sediment buildup and recommends flushing about once a year (every six months with hard water). On electric heaters, one failed element also cuts capacity.

When to call a professional

• You smell gas (leave first).
• The breaker or the reset trips again.
• The pilot will not stay lit or the burner will not ignite.
• The heater is about 8 to 12 years old or older and having problems.
• Water is leaking from the tank.

What it usually costs

HomeGuide (2026) lists typical tank water heater repairs at $150 to $700: heating element or thermostat about $100 to $350, thermocouple about $100 to $325, gas control valve about $150 to $550. A new tank heater runs about $600 to $1,800 installed.

Frequently asked questions

Why do I have cold water but no hot water?

The water heater itself is not heating: no power or gas, a tripped reset, a failed element or thermostat, or a pilot or ignition problem.

How long do water heaters last?

A. O. Smith puts the average life of a water heater at about 8 to 12 years.

Related problems

• Water heater leaking
• Hot water smells like rotten eggs
• Breaker keeps tripping
• Low water pressure in one faucet or shower

Sources

• A. O. Smith: When to repair or replace your water heater
• Rheem: How often to flush your water heater
• A. O. Smith: Water heater maintenance guide
• HomeGuide: Water heater repair cost (2026)

This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.

Short answer: Find where the water is coming from. A leak at the cold or hot connections on top, or at the drain valve, can usually be repaired. Water from the temperature and pressure (T&P) relief valve means the tank may be overheating or over-pressurized: turn the heater off and call a plumber. Water seeping from the tank body or under the base usually means the tank has failed and must be replaced.

Quick diagnosis

What you notice	Most likely cause	What to check	Call a pro?
Drip from pipes on top	Loose fitting or corroded connector	Wipe dry and watch	Often
Water from the relief valve pipe	Overheating, high pressure or worn valve	Is the discharge pipe dripping or spraying?	Yes, promptly
Drip at the drain valve	Valve not fully closed or worn	Check that it is closed; look for a cap	Sometimes
Puddle under the tank, no visible source	Tank corrosion	Dry everything and inspect	Yes, usually replacement
Water near the heater but not from it	Condensation or another pipe	Check nearby pipes and the AC drain	Depends

Make it safe

1. Turn off power at the breaker (electric) or set the gas control to off or pilot (gas).
2. Close the cold water supply valve on top of the heater.
3. Protect the floor and anything nearby from water.

Leak from the tank means replacement

A. O. Smith states that a heater leaking around the base of the tank is probably due for replacement, while leaks from faulty valves or loose connectors can often be fixed. A. O. Smith also puts the average life of a water heater at 8 to 12 years.

The relief valve

The T&P valve opens to release water when temperature or pressure gets too high. Occasional drips can come from thermal expansion, but steady discharge is a warning. Do not cap or plug the relief valve pipe. A plumber should check the thermostat, the system pressure and whether an expansion tank is needed.

When to call a professional

• The tank itself is leaking.
• Water is coming from the relief valve.
• You cannot safely shut off gas or power.
• The heater is old and showing rust or noise.

What it usually costs

HomeGuide (2026) lists a T&P valve replacement at about $50 to $300 and a new tank water heater at about $600 to $1,800 installed.

Frequently asked questions

Is a leaking water heater dangerous?

A slow fitting leak mostly causes water damage. Water from the relief valve can signal overheating or excess pressure and should be checked promptly.

Can I still use my water heater if it is leaking from the bottom?

A leaking tank usually cannot be repaired. Shut it off and plan a replacement.

Related problems

• No hot water
• Hot water smells like rotten eggs
• Pipes banging (water hammer)
• Water stain on the ceiling

Sources

• A. O. Smith: When to repair or replace your water heater
• Rheem: How often to flush your water heater
• HomeGuide: Water heater repair cost (2026)

This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.

Short answer: If the smell is only in the hot water, the water heater is the likely source. The Minnesota Department of Health explains that a water heater can turn sulfate in the water into hydrogen sulfide gas, both by hosting sulfur bacteria and through a reaction with the magnesium anode rod. If the smell is in cold water too, the source is the water supply, not the heater.

Quick diagnosis

What you notice	Most likely cause	What to check	Call a pro?
Smell only in hot water	Water heater anode and bacteria	Compare hot and cold at the same tap	Often
Smell in hot and cold	Well water or supply (hydrogen sulfide)	Test the water	Water professional
Smell after the heater was off a while	Bacteria growth in standing water	Flush the tank	Sometimes
Smell near a drain, not the tap	Drain or sewer gas	Smell the water in a glass away from the sink	See sewer smell guide

Confirm the source

Fill a glass with cold water and another with hot, step away from the sink and smell each. If only the hot glass smells, it is the water heater. If both smell, the supply (often a private well) is the source.

Fixes the Minnesota Department of Health describes

• Replace the magnesium anode with an aluminum-type anode (ask the heater manufacturer or dealer what is compatible). Removing the anode entirely can shorten the heater’s life.
• Disinfect and flush the tank with a chlorine bleach solution; the smell can return if bacteria survive.
• Raise the temperature to 160°F for several hours to kill bacteria, then flush, only after confirming the relief valve works, and then lower the thermostat to prevent scalding.

Most homeowners have a plumber or water treatment professional do these steps.

When to call a professional

• The smell is in cold water too (water testing needed).
• You are not comfortable replacing an anode or shocking the tank.
• You are unsure whether it is gas: leave and call the gas utility.

What it usually costs

HomeGuide (2026) lists anode rod replacement by a professional at about $150 to $350; the part alone is about $20 to $50.

Frequently asked questions

Is rotten egg smelling hot water safe?

The Minnesota Department of Health says rotten egg smells rarely indicate sewage, but recommends testing well water for coliform bacteria and nitrate to be safe.

Why does only my hot water smell?

The water heater provides warm conditions for sulfur bacteria and a magnesium anode that drives the reaction producing hydrogen sulfide.

Related problems

• No hot water
• Water heater leaking
• Sewer smell in the house

Sources

• Minnesota Department of Health: Hydrogen sulfide and sulfur bacteria in well water
• Penn State Extension: Common drinking water problems and solutions
• HomeGuide: Water heater repair cost (2026)

This guide is general information, not a substitute for an inspection by a licensed professional. See our disclaimer.