Water heater repair, and when to stop repairing

What is water heater repair?

Most water heater faults are a component, and components are cheap. Thermocouples, gas control valves, heating elements, thermostats, dip tubes and relief valves are all replaceable on a unit that otherwise has life in it. There is one fault that is never repairable: a leak coming through the tank itself. The steel shell is glass-lined, and once that lining fails and the steel rusts through, there is no patch, weld or sealant that constitutes a repair. So the first question on any water heater call is not "what is it costing" - it is whether the water is coming from the tank or from something bolted to it.

Signs you need water heater repair

• No hot water at all - on gas, usually a pilot, thermocouple or gas control valve; on electric, an element, a thermostat, or a tripped high-limit reset
• Lukewarm water, or hot water that runs out unusually fast - a failed lower element on electric, or a broken dip tube sending cold water straight to the outlet
• Water that starts hot and turns cold within a minute or two, then recovers slowly
• Rumbling, popping or kettling on every heating cycle - sediment hardened onto the tank bottom
• A steady drip from the relief valve, or a discharge line that is always damp
• Rusty or discoloured hot water while the cold runs clear - the anode is spent and the lining is under attack
• A rotten-egg smell in the hot water only, which usually points to the anode rod rather than to the water supply
• Water pooling on the floor under the tank with no visible source above it - the one on this list that is not a repair

Seeing something not on this list? Browse water heater problems by symptom →

How water heater repair actually works

1. 1

   Find where the water is actually coming from

   This is the whole job on any leak call. Water runs down the outside of a tank and pools at the bottom regardless of where it started, so the source has to be traced upward - the cold inlet, the hot outlet, unions and nipples, the relief valve and its discharge line, the drain valve, or the shell itself. A dry tank with a wet floor is a fitting problem. A weeping seam or a wet patch on the shell is not.

   Watch forA verdict of "the tank is gone" delivered from the doorway. If nobody has dried the unit and watched where it re-wets, the diagnosis is a guess, and it happens to be a guess that sells an appliance.

2. 2

   Test the component, do not swap it speculatively

   Electric elements and thermostats can be tested electrically; a gas control and thermocouple can be checked for output; a dip tube failure has a distinctive signature. Diagnosis is quick when someone brings the right meter and knows what reading they expect.

   Watch forParts being replaced in sequence until the symptom stops. You pay for every step of that, and it usually ends with a recommendation to replace the unit anyway.

3. 3

   Weigh the repair against what is left of the unit

   The honest calculation is the repair price against the remaining useful life and the cost of a replacement. A cheap part on a unit still under tank warranty is an easy yes. The same part on a heavily corroded tank whose anode has been gone for years is money spent on a unit that will fail on its own schedule regardless.

   Watch forThe age of the unit not being established. The data plate carries the manufacture date, and it should be read before the repair-versus-replace conversation, not after.

4. 4

   Fix the cause, not just the symptom

   A relief valve that keeps discharging is often reporting excess pressure rather than failing - that points at a closed system without expansion control, or a supply pressure problem, and swapping the valve just removes the messenger. Sediment noise points at water quality and a flushing habit that has lapsed.

   Watch forA relief valve replaced with no discussion of why it was discharging. If pressure is the cause, the new valve will do exactly the same thing, and it is doing its job when it does.

5. 5

   Leave with the expected life stated out loud

   After a repair you should know roughly what you have bought - whether this is a unit likely to run for years or one being kept alive until you can plan a replacement properly rather than in an emergency at 9pm.

   Watch forNo opinion offered on remaining life. A tech who has just had the unit apart has the best view anyone will get of it. Ask directly, and plan the replacement on your timetable rather than the tank's.

What does water heater repair cost?

Component repairs commonly land roughly $150 to $700 depending on the part and access, which is a fraction of a replacement. Tank shell failures are not repairable at any price. See the cost guide for how repair and replacement compare.

See the full water heater repair cost guide - by material, size and region →

If the number is the problem, here are the ways people pay for it →