Hot water system leaking? Where it's coming from and whether it's an emergency

Water pooling around your hot water system is unsettling, but not every leak means the same thing. Some are minor and expected. Some mean the tank is on its way out. A small number need attention straight away. Here is how to tell which is which, and what we look at before recommending a repair or a replacement.

The three places a leak usually comes from

Before anything else, work out where the water is actually coming from. This changes everything about how urgent it is and what fixes it.

Each of these tells a different story, so it is worth looking closely before assuming the worst.

• The temperature and pressure relief (TPR) valve, usually on the side or top of the unit, with a pipe running down to the ground.
• The tank body itself — the main cylinder that stores the hot water.
• Fittings and connections — the pipes, valves and joins where water lines connect to the unit.

TPR valve drip: usually not an emergency, but not nothing either

The TPR valve is a safety device. It is designed to release water if pressure or temperature inside the tank gets too high, and a small amount of dripping from its outlet pipe is sometimes normal, especially after the system has been heating water and pressure has built slightly. An occasional drip on its own is not usually cause for alarm.

A steady, ongoing drip or a constant trickle is different. That can mean:

A dripping TPR valve is a repair, not usually a full tank replacement, and it is worth fixing promptly because a valve that is failing to seal properly is also a valve you are relying on to work correctly if pressure actually spikes.

• The valve itself has failed and is no longer sealing properly
• Pressure in your water supply is running higher than it should
• Sediment or mineral build-up is stopping the valve from seating correctly

Tank body leak: this one matters more

If water is coming from the body of the tank itself — a crack, a rusted section, or seepage from the cylinder wall — that is a different situation. Storage tanks are not designed to be patched or resealed once the tank body itself has failed. Once the cylinder is compromised, it is generally at the end of its working life, and the leak will not improve on its own.

Signs the leak is coming from the tank body rather than a fitting:

A tank body leak is a replacement situation in almost every case. Trying to patch a failed cylinder is not a durable fix, and continuing to run the system risks a bigger and messier failure later.

• Rust staining or discolouration on the tank's outer casing
• Water appearing to seep from a seam or the base of the unit rather than from a pipe or valve
• The leak getting worse over days or weeks rather than staying constant

Fittings and connections: often the easiest fix

Leaks at a valve, an inlet or outlet connection, or a joint in the pipework near the unit are usually the least serious of the three, and often the cheapest to put right. These are mechanical connections rather than the tank itself, so a worn washer, a loose fitting or a failed seal can usually be repaired without touching the tank. If your leak is coming from a visible pipe joint rather than the tank body, there is a reasonable chance the unit itself is fine.

When to switch the system off

If you cannot immediately tell where the leak is coming from, or the leak is more than a slow drip, it is worth switching the system off while you arrange for someone to look at it.

This is about limiting damage while you wait for a proper diagnosis, not a permanent fix. Our burst and leaking pipes service covers the wider range of leak situations beyond the hot water unit itself.

• Electric storage systems — switch off at the isolation switch or the circuit breaker for the unit.
• Gas storage or continuous flow systems — the gas isolation valve at the unit can generally be turned off; if you are unsure, treat it as a job for a licensed gas fitter rather than guessing.
• Water supply — the cold water isolation valve feeding the unit can be turned off to stop water continuing to flow through a failing tank.

Why a leaking hot water system should not wait

Water pooling near an electrical or gas appliance is a hazard in its own right, separate from the question of what the leak means for the tank. An electric storage unit leaking near its wiring, or a gas unit leaking near its connections, is a reason to isolate power or gas at the unit rather than leave it running while you decide what to do. Beyond safety, a slow leak left unattended for weeks can damage flooring, timber framing, or nearby fittings, turning a hot water repair into a bigger job than it needed to be. Catching a leak early and getting it assessed properly is almost always the cheaper path, whatever the eventual verdict on repair versus replacement turns out to be.

Repair or replace: how we make the call

This is the question everyone wants answered straight away, and the honest answer depends on where the leak is and the condition of the rest of the unit.

If your existing unit can be saved, we tell you. We are not in the business of replacing tanks that only need a valve or a washer.

• Fitting or connection leak, tank otherwise sound — repair. Often a same-visit fix.
• TPR valve failure, tank otherwise sound — repair, replacing the valve.
• Tank body leak — replacement in almost every case, regardless of the unit's age, because the cylinder itself cannot be reliably repaired.
• Older unit with a fitting leak — this is the judgement call. If the tank is near the end of its typical lifespan and starting to show other signs of wear, repairing a fitting on a unit that is likely to fail elsewhere soon is not always the best use of money.

What this costs

Most residential hot water replacements, supplied and installed, run $1,200 to $3,000, depending on the type and size of system. A fitting or valve repair is a smaller job, priced separately and clearly before work starts. You hear the number before we start, not after. For more on diagnosing hot water faults generally, see our hot water issues page, or hot water replacement if you suspect the tank itself has reached the end of the road.

When to call a plumber

A leak you catch early is usually a cheaper fix than one left to run. If in doubt, switch off what you safely can and get it looked at.

• Water is pooling around the base of the unit, however small the amount.
• The TPR valve is dripping constantly rather than occasionally.
• You notice rust staining on the tank's outer casing.
• The leak is getting worse day to day.
• You are unsure where the water is coming from and want it checked before it gets worse.

Get it looked at properly

Not sure if your hot water leak is a five-minute fix or a sign the tank has had it. We check the tank, the valve and the fittings, then tell you straight which one it is and what it costs to fix. Call Dave on 0409 364 858, serving Redland Bay, Capalaba and right across the Redlands and Brisbane bayside. Lifetime workmanship guarantee: it works when we leave, or we come back and fix it.