Replace your water heater when the tank itself leaks, the hot water runs rusty, it rumbles from built-up sediment, or it is past its expected life, which is about 8 to 12 years for a standard tank. A pilot that won't stay lit, lukewarm water, or a smelly hot tap usually points to a cheaper repair.
Clear signs it's time to replace the water heater
The clear signs are an old tank, rusty hot water, a leak from the tank body, sediment rumbling, a shrinking hot water supply, and repeat repairs.
The tank is past its expected life
Rheem puts a standard tank at 8 to 12 years and a tankless unit at 15 to 20 years or more with regular care. Heat pump (hybrid) models generally last 10 to 15 years. To find the age, read the serial number on the data plate, where most brands encode the manufacture date.
Rusty or discolored hot water
Rust in the hot water often means the anode rod is used up and the tank is corroding from the inside. If only the hot tap runs brown, the heater is the likely source. If both do, check the pipes. In a young tank, a new anode rod can slow the damage. In an older tank, rust usually means the end is close.
Water leaking from the tank body
A leak from the tank body or the bottom seam can't be repaired, because the tank has rusted through. Dry the area and find the highest wet spot. Water from a pipe connection on top, the drain valve, or the relief valve pipe is usually a repair. Water seeping from the base is the tank. Once you confirm a tank leak, shut the cold water supply valve above the heater. Switch off the breaker for an electric unit, or turn a gas unit's control to off if you smell no gas.
Rumbling or popping from sediment
Rumbling or popping during a heating cycle means sediment has built up on the bottom of the tank. Water trapped under it boils, which makes the noise and overheats the steel. Flushing helps when the layer is new, but hardened sediment in an older tank means it is wearing out faster.
You run out of hot water sooner
Hot water that runs out sooner can be a repair or a sign of decline. A failed lower heating element or a broken dip tube is a repair. If you still run short after the fix, sediment is taking up the tank or it's too small for your household.
Repairs keep coming back
A second or third repair call in a year on an aging tank means it's time to stop repairing, because no part fixes a corroding tank.
Symptoms that usually mean a cheaper repair
Many water heater problems come from one worn part that a plumber can replace in a single visit. These symptoms rarely mean you need a new tank:
- The pilot won't stay lit, or the burner won't fire (gas): a worn thermocouple, or the igniter or flame sensor on newer models.
- No hot water or lukewarm water (electric): a failed heating element. Most electric tanks have two, and losing one leaves water lukewarm.
- Water too hot, or a temperature that swings: a faulty thermostat.
- A rotten-egg smell in the hot water: the anode rod reacting with bacteria in the water, which is common with well water. A different type of rod usually fixes it.
- A drip from the relief valve pipe: a worn temperature and pressure relief valve, or water pressure that's too high. Have a plumber check it.
When to stop and call a pro right away
Stop and call a licensed pro if you smell gas, the relief valve leaks or hisses, or you see scorching at the burner.
- You smell gas near the heater. A rotten-egg smell in the air around a gas water heater is a possible gas leak. Leave the house, don't use light switches, phones, or lighters inside, and call your gas utility or 911 from outside. Don't try to relight the pilot.
- The relief valve is leaking, spraying, or hissing. The temperature and pressure relief valve opens when the tank gets too hot or the pressure gets too high, or when the valve itself is failing. The water can scald. Keep clear, never cap or plug the valve or its pipe, and call a licensed plumber.
- You see scorch marks, soot, or melted parts at the burner. Scorching around the burner access door can mean flames are rolling out or the vent is blocked, which can push carbon monoxide into the house. Stop using the heater and call a licensed plumber or your gas utility. If a carbon monoxide alarm sounds, get everyone outside and call 911.
How much repair costs compared with replacement
Most single-part repairs cost a few hundred dollars, while a new water heater ranges from under $1,000 for a basic tank to several thousand for tankless or heat pump models. HomeGuide puts typical repairs at $150 to $700, and Fixr gives $150 to $750 with an average of $450. For individual parts, their 2025 and 2026 cost guides list:
- Thermocouple: $100 to $325 (HomeGuide), $150 to $325 (Fixr).
- Heating element: $100 to $350 (HomeGuide), $200 to $750 (Fixr).
- Anode rod: $150 to $350 (HomeGuide), $125 to $300 (Fixr).
- Temperature and pressure relief valve: $50 to $300 (HomeGuide), $100 to $250 (Fixr).
- Thermostat: $100 to $250 (Fixr). Angi puts a typical thermostat job near $200 with labor.
Replacement costs depend mostly on the type of heater:
- Standard tank: Angi reports $882 to $1,825, with an average of $1,347. HomeGuide gives $600 to $3,100, with gas tanks costing more than electric.
- Tankless: Angi reports $1,400 to $3,900. HomeGuide gives $1,400 to $5,600, with gas tankless at $2,100 to $5,600 because it often needs new venting and a larger gas line.
- Heat pump (hybrid): HomeGuide gives $2,000 to $4,600 installed. Today's Homeowner puts the average near $3,600, within a range of $1,200 to $6,000.
Switching types costs more than a like-for-like swap, because venting, gas lines, or wiring may change.
Do you need a permit?
Many cities and counties require a permit to replace a water heater, but not all do. Angi puts permit fees at $25 to $300 depending on the city and the heater, and HomeGuide lists $50 to $200 for gas or electrical permits. The licensed plumber usually pulls the permit. When you compare contractor quotes, check whether each one includes the permit, haul-away of the old tank, and code updates such as an expansion tank or, in some states, earthquake straps.
How to decide between repair and replacement
Replace the heater when the tank leaks or rusts, and repair it when one part has failed on a tank that's still sound. For everything in between, weigh the repair price against the tank's age. Rheem's rule of thumb is to replace the unit when a repair costs more than half the price of a new one, and Fixr suggests weighing a new heater once a repair bill reaches $1,000.
Before you ask for contractor quotes, photograph the data plate, the vent pipe, the shutoff valves, and the floor around the base.
If you rent, report a leaking tank to your landlord in writing the same day. In a mobile or manufactured home, the new heater usually has to be a model rated for manufactured housing, which limits your choices and can change the price.
Common questions
How long does a water heater last?
A standard tank water heater lasts about 8 to 12 years, and a tankless unit can last 15 to 20 years or more, according to Rheem. Hard water and skipped flushing shorten that life.
Can a leaking water heater be repaired?
It depends on where the water comes from. A leak at a pipe fitting, the drain valve, or the relief valve can usually be fixed, but a leak from the tank body means the tank has rusted through and needs replacing.
Is it worth repairing a 10-year-old water heater?
Usually only for a cheap, single-part fix on a tank with no rust, leaks, or rumbling. At 10 years a tank is near the end of its life, so a bigger repair often goes into a unit that fails soon anyway.
Why does my hot water smell like rotten eggs?
Bacteria in the water reacting with the anode rod usually cause it, and a different type of rod often fixes it. If the smell is in the air around a gas heater instead of in the water, treat it as a gas leak and call your gas utility from outside.