Water heater: repair or replace?

A conventional gas or electric tank water heater typically lasts 8 to 12 years. Tankless units run considerably longer, usually 15 to 20 years. That range matters more than almost anything else in this decision, because the same $200 repair means something completely different depending on where in that lifespan your unit sits. On a 3-year-old heater, a $200 repair is an easy call. On an 11-year-old heater, that same repair might only buy you another year before something else fails, at which point you've paid for a repair and a replacement instead of just the replacement.

If you don't know the age of your unit, it's printed on a manufacturer's sticker on the tank itself, usually as a manufacture date or the first few digits of the serial number. Worth checking before making any decision, since guessing at age is where most bad calls happen.

If the tank itself is leaking, this stops being a repair-or-replace question. A steel tank that has corroded through cannot be patched or repaired in any meaningful way, and a failed tank can release 40 or more gallons onto your floor without warning. Regardless of the unit's age or how much you've already invested in it, a leaking tank means replacement. This is the same category as a cracked engine block or a foundation crack running through a load-bearing wall: the container itself has failed, not a part inside it.

Everything else covered below assumes the tank itself is sound and the failure is something repairable.

Most water heater problems trace back to one of a small number of parts, and the repair costs vary enormously depending on which one it is. A pilot light that's gone out costs nothing to fix yourself. A failed thermocouple, the most common reason a gas water heater won't ignite, runs $150 to $300 professionally installed and typically buys 1 to 3 more years of service. A failed gas control valve is a bigger job, $300 to $500, for roughly the same amount of additional life.

If the complaint is not enough hot water rather than no hot water at all, the usual causes are sediment buildup in the tank ($100 to $250 to flush, buying 1 to 3 years), a broken dip tube ($150 to $350, buying 2 to 4 years), or a failed thermostat ($150 to $300, buying 1 to 3 years). A leak from a fitting or valve, as opposed to the tank itself, is usually a $100 to $300 repair and can buy 3 to 6 more years, since these are wear parts rather than a sign the tank is failing.

The pattern across all of these: the repair cost is rarely the problem. The years of life it buys you, relative to the unit's age, is what actually determines whether it's worth doing.

Comparing a $300 repair to a $1,800 replacement sounds like the repair obviously wins. But that comparison only makes sense if you also compare what each option buys you in years of service. A full replacement gets you a fresh 8 to 12 year lifespan, roughly averaging out to $150 to $220 a year over that span. A $300 repair on a unit that's already 10 years old, buying you maybe 1 more year, works out to $300 a year, genuinely worse value than just replacing it, even though the upfront number is smaller.

This is the calculation most people skip, and it's the reason a technically working, cost-effective-sounding repair can still be the wrong financial decision on an older unit. The repair isn't a bad idea because it's expensive. It's a bad idea when the cost per year of life it buys is worse than what a new unit would cost per year over its own full lifespan.

A mid-range 40-gallon gas water heater, installed with a permit, typically runs $1,435 to $2,220. That figure already accounts for the unit itself, standard installation, and the permit most jurisdictions require for water heater work. Tankless units and higher-efficiency models cost more upfront but last longer and run more efficiently, which is worth factoring in if you're already leaning toward replacement rather than treating it as a separate decision.

Worth noting separately: a water heater at the end of its life typically costs $30 to $80 more per year to operate than a new one would, purely from efficiency loss. That's a real, ongoing cost that doesn't show up on any repair invoice, and it's part of why an aging unit is sometimes worth replacing even when nothing has technically failed yet.

Most water heaters carry a manufacturer's warranty somewhere between 6 and 12 years, and it's worth checking before assuming a repair or replacement is coming entirely out of pocket. If your unit is still within its warranty window, a failed part, sometimes even the whole tank, may be covered or significantly discounted. This single check can change the entire calculation, and it's the first thing worth doing before calling anyone, not the last.