Signs Your Water Heater Is Failing (Repair or Replace?)

Most water heaters give warning before they fail. ENERGY STAR and Rheem point to corrosion, leaks, rusty water, rumbling noises and running out of hot water sooner. Some of these are repairable. A leak from the tank itself is not, and A.O. Smith says a unit over 10 years old with several symptoms is usually due for replacement.

Stop and call a pro now if

  • Water is pooling around the base of the tank or spraying from a fitting. If you can reach it without getting sprayed, turn off the cold water supply valve on top of the heater. If not, shut off the home's main water valve. Then turn off the heater's power or gas. Don't stand in water to reach the breaker panel.
  • The relief valve is releasing hot water or steam. Stay clear of the discharge pipe, turn off the power or gas, and call a plumber. Never cap or plug the discharge pipe.
  • You smell gas (a rotten-egg smell in the air) near a gas heater. Leave the house without switching anything on or off, and call your gas utility or 911 from outside.
  • You see scorch marks, soot around the burner door or vent hood, or melted wiring. Turn off the gas or power and call a plumber. On a gas heater, soot can mean poor venting and carbon monoxide. If your CO alarm sounds, get everyone outside and call 911.

Likely causes

  • Water around the base

    Rheem notes some leaks come from loose fittings, the temperature and pressure relief valve or condensation. Water coming from the tank body usually means it has corroded through, and the only fix is replacement.

  • Rusty or discolored hot water

    ENERGY STAR says rust in the water usually means the inside of the tank is corroding. Rheem adds it can also come from a worn-out anode rod, which can be replaced.

  • Rumbling or popping

    Sediment settles on the bottom of the tank and the burner or element has to work harder to heat through it. ENERGY STAR and Rheem both tie these noises to sediment buildup.

  • Running out of hot water sooner

    Sediment takes up space in the tank. Rheem lists a failing thermostat, a burned-out element or a damaged dip tube as other causes.

  • Corrosion on the fittings or tank

    ENERGY STAR calls visible corrosion around the water lines or on the unit a sign the heater is breaking down.

  • A dripping relief valve

    A relief valve that drips or discharges isn't always failing. High house water pressure, or a missing or failed expansion tank, can push it open. A plumber will check the pressure before replacing the valve.

  • Smelly hot water

    A rotten-egg smell only in the hot water usually comes from a reaction between the anode rod and bacteria in the water, not a gas leak. Rheem lists smelly water among its warning signs. A plumber can swap the anode rod.

  • Age

    A.O. Smith puts typical water heater life at about 8 to 12 years. ENERGY STAR suggests planning a replacement once a heater passes 10 years, before it fails.

What you can safely check

These checks are visual. Leave the access panels, the relief valve and the gas controls alone.

  1. Find the age

    Read the label on the tank. ENERGY STAR notes the manufacture date is sometimes printed there. If not, decode the serial number with the brand's chart on its website.

  2. Trace any water to its source

    Dry the floor and look again in a few hours. Water on top of the tank at the pipe connections or dripping from the relief valve pipe is often repairable. Water seeping from the tank body is not.

  3. Compare hot and cold water

    Run cold water, then hot water, into a white cup. Rust only in the hot water points to the heater. Rust in both points to your pipes or water supply.

  4. Listen while it heats

    Rumbling or popping while the burner or elements run is a sign of sediment.

  5. Note how long the hot water lasts

    If showers run cold noticeably sooner than they used to, write down roughly how long. The plumber will ask.

Avoid these

  • Lifting the relief valve lever on a hot tank to test it. Scalding water can shoot out. Leave that test to a plumber.
  • Draining or flushing a tank that is over 10 years old and has never been flushed. Opening an old drain valve can start a leak that won't close.
  • Ignoring a small drip from the tank body. Rheem warns a compromised tank can suddenly release much more water.

When to call a pro

  • Water is coming from the tank itself.
  • The hot water is rusty or brown and the cold isn't.
  • The heater rumbles loudly or hot water runs out much sooner than before.
  • The heater is over 10 years old and needs any major part.

Tell the plumber the heater's age, whether it is gas or electric, and which signs you saw. Ask for a repair quote and a replacement quote together. A.O. Smith says replacement is usually the better path for a unit over 10 years old with multiple symptoms.

Typical repair costs

National ranges for parts and labor from HomeGuide. Replacement prices vary with tank size, fuel type and venting.

Repair Typical cost Source
Typical water heater repair $150–$700 HomeGuide
Anode rod replacement $150–$350 HomeGuide
Tank flush and clean $75–$250 HomeGuide
Pressure relief valve replacement $50–$300 HomeGuide
Heating element replacement (electric) $100–$350 HomeGuide
Thermocouple replacement (gas) $100–$325 HomeGuide
Dip tube replacement $100–$300 HomeGuide
New 40–50 gallon tank heater, installed $600–$3,100 HomeGuide
New tankless water heater, installed $1,400–$5,600 HomeGuide

Replacing a heater before it fails gives you time to compare models and quotes. ENERGY STAR warns an emergency replacement can cost more and limit your choices.

Frequently asked questions

How long do water heaters last?

A.O. Smith puts the typical service life at about 8 to 12 years. Water quality, maintenance and installation shift that range.

Can a leaking water heater be repaired?

A leak from a fitting, the drain valve or the relief valve usually can. A leak from the tank body cannot, because the steel has corroded through.

Is rusty hot water dangerous?

It isn't usually a health hazard, but it is a sign of corrosion. Rheem notes it can come from a worn anode rod, which is replaceable. If the rust keeps coming back, the tank is likely near the end of its life.

Should I repair or replace a 10-year-old water heater?

A.O. Smith says replacement is often the smarter move at that age, especially with more than one symptom. A single cheap part such as a relief valve can still be worth replacing.

Sources

  1. When Should You Replace Your Water Heater? , ENERGY STAR
  2. 5 Signs Your Water Heater Is Going Bad (And What to Do About It) , Rheem
  3. When to Repair or Replace Your Water Heater , A.O. Smith
  4. Water Heater Repair Cost , HomeGuide
  5. How Much Does Water Heater Installation Cost? , HomeGuide

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