Water Heater · Service

Water heater repair, and when to stop repairing

Most water heater faults are a cheap part. A few mean the unit is finished. Work out which one you have before anyone quotes you for a new tank.

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In short

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.

Triggers

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 →

The job

How water heater repair actually works

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 for: A 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.
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 for: Parts 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.
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 for: The 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.
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 for: A 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.
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 for: No 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.

Money

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 →

Straight answer

When water heater repair is the wrong call

Everyone else ranking for this is paid when you say yes. Here's when you shouldn't.

The leak is coming through the tank shell. Glass-lined steel that has rusted through cannot be repaired. Any offer to seal, weld or patch it is either a misunderstanding or a stalling tactic, and the tank will fail properly at some point of its own choosing.
The repair is a large fraction of a replacement on an already old unit. Once the quote approaches a meaningful share of a new installed heater, you are buying uncertain time on a unit whose next fault is somebody else's guess.
You have already replaced two components this year. Multiple failures in quick succession usually mean the whole unit has aged rather than one part having bad luck. Keep repairing and you fund the replacement twice.
You were already planning to change type. If a tankless or heat pump unit is on your list for next year, spending on the old tank now buys nothing you keep. Bring the replacement forward instead.
The unit is undersized for the household and always has been. No repair fixes "we run out of hot water when three people shower". That is a sizing outcome, and repairing components will not change it.

Before you sign

What to check when hiring for water heater repair

Can you show me exactly where the water is coming from?

The single most valuable question on a leak call, and the one that separates a diagnosis from a sales opportunity.
What is the manufacture date on the data plate?

It frames every other decision. A unit still inside its tank warranty is worth repairing on terms an old one is not.
Is the tank still under warranty, and have you checked?

A covered tank changes the maths entirely. It is easy to check by serial number and easy for a busy tech to skip.
What test told you that part had failed?

You want a measurement, not a hunch. Speculative part-swapping is billed to you one part at a time.
Why did this fail, and will the replacement part do the same?

Relief valves, elements and thermocouples usually fail for a reason. Fixing the symptom alone means a repeat callout.
How long do you expect this unit to last after the repair?

It lets you choose the timing of your replacement instead of having it chosen for you at an inconvenient hour.

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Local pros

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Related work

Often done at the same time

Water Heater Replacement

When repair is no longer the answer

Emergency Water Heater Replacement

A tank failing right now

Water Heater Maintenance

Preventing the next fault

Expansion Tank Installation

The fix behind a dripping relief valve

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FAQ

Water Heater Repair — questions people ask

Still have a question? Talk to our team →

Is a leaking water heater always a replacement?

No — and this is the most valuable distinction on the page. Leaks from the cold inlet, the hot outlet, a union, the drain valve or the relief valve are fittings, and fittings are repairable. A leak coming through the tank shell itself is not, because the glass lining has failed and the steel behind it has corroded through. Have somebody establish which one you have before agreeing to anything.

Why do I have no hot water at all?

On a gas unit the usual suspects are the pilot, the thermocouple, or the gas control valve — all replaceable parts. On an electric unit it is most often a failed element, a failed thermostat, or a tripped high-limit reset behind the upper access panel, which itself trips for a reason worth finding. In both cases the fault is a component far more often than the tank.

What makes the banging and popping noise?

Sediment. Minerals settle out of the water and bake onto the tank bottom, and steam bubbles forming under that layer produce the popping. It insulates the burner or the lower element from the water, so the unit works harder and the bottom of the tank runs hotter than it should. Regular flushing prevents it; once the deposit has hardened, flushing helps less and the noise tends to stay.

Why does my hot water smell like rotten eggs?

Usually a reaction between the anode rod and bacteria in the water. It is characteristic that the smell appears only on the hot side — if the cold smells too, the issue is the water supply rather than the heater. Changing the anode rod material is the usual remedy, and it is a job worth having done at the same time as any other service on the unit.

My relief valve keeps dripping. Do I need a new valve?

Possibly, but check the cause first. A relief valve discharges when pressure or temperature exceeds its rating, which frequently means a closed plumbing system with no expansion tank, or high incoming supply pressure. In that case the valve is doing its job and a new one will drip identically. Never plug, cap or restrict the discharge line — it is a safety device.