Should I repair or replace my water heater?

The quick decision table

Situation	Usual answer	Why
Tank leaking from the body	Replace	A rusted-through tank cannot be repaired
Tank under 6 to 8 years, one failed part	Repair	Rheem's guidance for units with no structural damage[1]
Tank 8 to 10 years, cheap part (thermocouple, element)	Usually repair	Low cost buys time; start planning a replacement
Tank 10+ years, any significant repair	Usually replace	Failure risk rises past 10 years, per Rheem[1]
Repair quote above 50% of a new unit	Replace	Rheem's 50% rule[1]
Tankless under 10 years, sensor or fan fault	Repair	Tankless units often last 15 to 20+ years[2]
Tankless with a failed heat exchanger out of warranty	Compare carefully	Heat exchanger repairs run $600 to $1,300[3]
Hot water runs out, household grew	Replace or resize	A repair will not fix an undersized unit

Step 1: find the real age

The age on the sticker matters more than how long you have lived in the house. Every major brand encodes the build date in the serial number on the rating plate, and our age decoder reads most of them. Two reasons this matters:

• Lifespan. Rheem and A.O. Smith put typical tank life at 8 to 12 years, and tankless at 15 to 20 years or more with care^[1][2].
• Warranty. Many warranties are dated from manufacture, not install. Lochinvar's warranty, for example, starts its tank coverage 60 days after the manufacture date shown in the serial number^[7]. A tank that sat in a warehouse uses up some of its coverage before it is installed.

A myth to ignore: some cost sites say tanks last "8 to 15 years" or longer. The makers themselves say 8 to 12^[1][2]. Plan on the makers' number.

Step 2: price the repair against the replacement

Rheem's rule is simple: if the repair costs more than 50% of a new unit's price, replacement is almost always the better investment^[1].

Typical repair costs, from HomeGuide's August 2025 national data^[3]:

Repair	Typical range
Thermocouple	$100 to $325
Heating element	$100 to $350
Thermostat	$100 to $350
Anode rod	$150 to $350
Gas control valve	$150 to $550
Relief valve	$50 to $300
Expansion tank	$300 to $800
Tankless heat exchanger	$600 to $1,300

HomeGuide's national average for a tank repair is $455, based on 349 reported projects, and service call fees of $50 to $200 may apply^[3].

Replacement costs vary more. HomeGuide's January 2026 guide puts a standard 40 to 50 gallon tank at $600 to $3,100 installed and a tankless install at $1,400 to $5,600^[4]. ProjectCostPro's July 2026 planning ranges, which include an expansion tank, drain pan and permit, run higher: $2,900 to $5,050 for a 50-gallon gas tank and $2,700 to $4,650 for 50-gallon electric^[8]. See our replacement cost guide for why the sources differ.

Worked example. Your 9-year-old 50-gallon gas tank needs a gas control valve, quoted at $450. If a like-for-like replacement in your area is quoted at $1,800, the repair is 25% of replacement, so it passes the 50% test. But the tank is close to the end of Rheem's 8 to 12 year range, so the $450 may buy only a year or two. Many owners in that spot replace. If the same tank were 4 years old, repair is the clear call.

Step 3: check for signs the tank is failing

Repairs are a poor bet when the tank itself is wearing out. Warning signs:

• Water seeping from the base or under the jacket (not the relief valve or drain valve).
• Rusty or brown water from the hot taps only.
• Rust on the tank, fittings or the base.
• Loud rumbling that flushing does not reduce.
• Recovery getting slower year over year.

Any one of those on a tank past 8 years is a reason to replace rather than repair. Our signs you need a new water heater page covers each.

Step 4: know what replacing will involve

Replacement is more than a swap:

• Permit and inspection. Many cities require both. Some, like Houston, require that a city-registered master plumber pull the permit^[9]. See our state pages.
• Code upgrades. An older install may need an expansion tank, a drain pan, venting changes or a new gas connector to meet current code. These add to the price^[8].
• No federal tax credit in 2026. The IRS says the 25C Energy Efficient Home Improvement Credit is not allowed for property placed in service after December 31, 2025^[5]. Utility rebates may still apply. See 25C status.
• The 2029 efficiency rule. For units made on or after May 6, 2029, electric storage heaters in the most common sizes must reach entry-level heat pump efficiency; gas storage heaters face a moderate increase^[6]. It does not affect what you can buy today.

Repairs that usually pay off, and ones that rarely do

Usually worth it on a sound tank: a thermocouple ($100 to $325), a heating element or thermostat ($100 to $350 each), a relief valve ($50 to $300), or a flush ($75 to $250)^[3]. These are small parts on a tank that may have years left.

Rarely worth it on an older tank: a gas control valve ($150 to $550) or any combination of repairs on a tank past 10 years, and anything at all once the tank itself leaks^[1][3]. The money is better spent toward the replacement.

Tankless units: a different math

Tankless heaters last longer, so a repair at year 8 can still be worth it. The big-ticket risk is the heat exchanger. Scale is its main enemy: A.O. Smith names hard water mineral deposits as the primary failure cause^[2]. If your unit has gone years without a flush and now shows scale codes, budget for descaling before deciding.

When to call a pro

• Any leak from the tank body: get replacement quotes.
• A repair quote you want to test against the 50% rule: ask for a written replacement price too.
• Any gas, electrical, venting or relief valve work.
• Warranty questions: the installer or maker can confirm coverage from the serial number.