A water heater is a simple machine: a tank, a way of heating it, and controls. Most failures are in the controls or the heating, and most of those are repairable.
One failure is not, and it is worth knowing which is which before anyone quotes you.
The failure that ends it
The tank body leaking. Water heaters fail from the inside out. The steel tank is protected by a lining and by a sacrificial anode rod, and once that protection is exhausted the tank corrodes. When it finally goes, it goes through the wall of the tank.
That is not repairable. There is no patch for a corroded tank, and a tank that has started leaking will get worse — sometimes gradually, sometimes suddenly and completely.
If you are told the tank body is leaking and you should replace it, that is correct advice, not an upsell. You can verify it yourself: water coming from the bottom of the tank, not from a fitting or valve at the top.
The failures that are repairable
Heating element, in an electric tank. A consumable part and a routine replacement. A failed lower element is the classic "runs out of hot water quickly" symptom.
Thermostat, electric or gas. Controls the temperature, fails predictably, replaceable.
Thermocouple or pilot assembly, in a gas tank with a standing pilot. The safety device that proves the pilot is lit. It is the most common single failure on an older gas tank and it is a small part.
Gas valve. More significant in cost, and it is where the arithmetic starts to matter on an older tank.
Temperature and pressure relief valve. A safety device that opens if pressure or temperature gets too high. If yours is weeping, it needs attention — either it has failed, or it is doing its job because something else is wrong, and that distinction has to be established rather than assumed.
Anode rod. The sacrificial rod that corrodes so the tank does not. It is consumable, and replacing it before it is entirely gone extends tank life meaningfully. Almost nobody does this, which is part of why tanks fail when they do.
How to think about the decision
The usual rule — replace when the repair approaches a large fraction of replacement — is a reasonable starting point but it misses two things.
Age matters on its own. A significant repair on a tank near the end of its service life is buying an unknown amount of time. The same repair on a young tank is straightforwardly worth doing. A technician who has looked at yours can tell you roughly where it sits, and the serial number label usually encodes the date.
A replacement is a decision point, not just a purchase. It is the moment to reconsider size, fuel type, whether tankless or a heat pump water heater suits you better, and whether the location still makes sense. Those options are not available on a repair, and some of them have rebate programmes attached that a repair does not.
Sediment, and the maintenance nobody does
Minerals settle in the bottom of a tank over years. In a gas tank they insulate the burner from the water, which makes the tank work harder and can cause rumbling or popping noises. In any tank they occupy volume you paid for.
Flushing the tank periodically removes sediment, and combined with anode rod replacement it is the difference between a tank that reaches the end of its expected life and one that does not.
The reason almost nobody does either is that a working water heater asks nothing of you until the day it fails. That is a bad property in a machine sitting above a finished floor.
The thing worth doing regardless
Know where the shutoff for your water heater is, and know whether there is a drain pan under it with somewhere for the water to go.
A tank in a garage or an unfinished basement that fails is an inconvenience. The same tank in a closet on an upper floor, over finished flooring, with no pan and no drain, is a very different event. If that describes yours, it is worth addressing before it becomes relevant.
If yours is failing
Tell us gas or electric, roughly how old, and what it is doing. If there is water on the floor, tell us where it is coming from — that one detail usually determines the whole conversation.
Vancouver, Burnaby, Richmond, Coquitlam, Port Coquitlam, New Westminster. 604-865-7979.
Related: Hot water tank repair · Hot water tank replacement · No hot water
