Repaired where a repair is honest and replaced where it is not, starting with the question of whether the water you have found is a fault at all.
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One of the most common calls we get about hot water starts with somebody finding water near the tank and reasonably assuming the worst. Frequently they have found the system doing exactly what it is designed to do.
Every storage unit has a temperature and pressure relief valve. Water expands as it heats, and rather than allowing pressure to build inside a sealed cylinder, that valve lets the excess out through a discharge line. A small release while the unit is heating is not a fault. It is the safety device working.
What is a fault is a continuous discharge. A valve running steadily has either failed or is telling you the incoming pressure is higher than it should be, and either way that is mains water going down a drain around the clock. It is a repair, not a reason to replace a tank, and it is a fraction of the price.
The reason it goes unnoticed for months is geography. On plenty of properties here the unit sits at the side of the house and the discharge line finishes in a garden bed, which is not somewhere anybody checks. The first evidence is a bill.
That one is different, and it is the end of the unit. Shut it off and ring, because the flooring costs more than the cylinder does.
Water expands as it heats and the valve lets the excess go. A small discharge, occasionally, is the valve doing its job rather than a fault in it.
So a bit of water at the discharge point after the tank has heated is normal and not worth worrying about.
The distinction that matters is between occasional and continuous, and that is the whole of this page.
A valve running steadily has failed, or the incoming pressure is too high and it is relieving constantly because the system is being pushed above where it should sit.
Either way it is a fault with a cause, and either way it is putting a real volume of heated water somewhere it is not supposed to go.
It also costs money continuously, because every litre relieved was heated first and has to be replaced and heated again.
A garden bed at the side of the house is not somewhere anybody looks. Neither is a spot behind a screen, under a deck, or in a corner of a large garden.
Which is precisely why a failed relief valve can run for months here. On a big block there is a great deal of ground nobody walks on.
Go and find yours. It is a small pipe from the top or the side of the unit, terminating somewhere at ground level, and it is worth knowing where.
The domestic ceiling is 500 kPa static at any outlet, and a pressure limiting valve is what holds a property below it. Those wear out at around eight to twelve years and they fail open.
A relief valve discharging continuously is one of the ways an over-pressured property announces itself, alongside taps that keep dripping after repair and new water hammer.
It is worth measuring rather than replacing the relief valve and hoping. A gauge and two minutes tells you which problem you have.
Water put repeatedly into one spot beside a building is worth caring about, particularly on a slope, and these streets have plenty of slope.
It is also a nuisance rather than a catastrophe in most cases. The point is that it is doing something rather than nothing, and nobody chose it.
Redirecting a discharge line to a drain or a gully is a short job and it is worth doing whether or not the valve is currently faulty.
That points at the cylinder rather than at the supply. Run the cold and it is clear, run the hot and it is rusty or grey, and the difference is coming from inside the tank.
It means the lining and the anode are no longer keeping water away from the steel, and what you are seeing is the steel.
It is a warning rather than an emergency, and it is the most useful one a hot water system ever gives.
A low rumble, crackle or knock as the unit heats is usually sediment sitting on the base of the cylinder, with water trapped underneath boiling its way out.
It is not dangerous in itself. It says the tank has accumulated material and the element or burner is now heating through a layer.
Taken with discoloured hot water, the two symptoms say the same thing from different directions, and a unit showing both is worth planning for.
Sydney water is soft, so cylinders here do not silt up the way they do in hard-water regions. What ends a tank here is corrosion of the steel.
The sacrificial anode exists to corrode instead, and once it has gone the tank starts spending itself. That is the mechanism behind almost every hot water failure in Sydney.
Renewing one costs a fraction of a replacement and buys years. Around the six or seven year mark it is the best value item on this page.
These houses are large and they have been added to, so the run from the unit to the furthest bathroom can be considerable. The water standing in that run has to be pushed out before hot arrives.
That is pipe length rather than a failing heater, and no work on the unit shortens it. Insulating the pipe helps at the margins and recirculation genuinely solves it.
The exception is a wait that has got noticeably longer than it used to be, because a change has a cause.
Where the water is coming from the cylinder wall, the steel has corroded through and the tank is finished. That is a straightforward diagnosis and it is not a negotiation.
A weeping fitting on top is a different thing entirely and it is usually a modest repair.
In the meantime, isolate the water and the power or gas, particularly if the unit sits anywhere the contents would do damage.
When a repair is no longer honest, the choice comes down to what the property will support and what you want it to cost to run. Here is how the five compare.
| Type | How it works | Expected span | What it asks of the property |
|---|---|---|---|
| Electric storage | A submerged element warms a stored volume | About 8 to 12 years | Very little beyond a position and a circuit |
| Gas storage | A burner beneath keeps the volume hot | About 8 to 12 years | Gas connected and flue clearances met |
| Continuous flow | Heated in transit, with nothing stored | About 15 to 20 years | Gas, and a compliant wall position |
| Heat pump | Ambient warmth moved into the tank | About 10 to 15 years | Outdoor space with genuine airflow |
| Solar with boost | Roof collectors with an element for poor weather | About 15 to 20 years | Roof area with a workable orientation |
A starting point rather than a rule. Storage is judged on how much can be drawn before it empties, so the number that counts is how many people want hot water inside one hour.
| Occupants | Electric storage | Gas storage | Continuous flow |
|---|---|---|---|
| One or two | 125 to 160 L | 90 to 135 L | 16 L/min |
| Three to four | 250 to 315 L | 135 to 170 L | 20 L/min |
| Five or more | 315 to 400 L | 170 L or twin | 26 L/min |
| Two bathrooms at once | Size up a step | Size up a step | 26 L/min |
Fixed price agreed before anything starts. These are indicative 2026 ranges.
Taken off the repair in full if you ask us to carry it out.
The answer to a valve that has started discharging continuously.
The most common electric fault, and the reason a cold tank is not automatically a dead one.
Cheap insurance on a cylinder with years left in it.
Unit, install and removal of the old one, in a single figure.
Electric storage through a great deal of the older housing here, gas where a property is connected for it, and continuous flow wherever a cylinder had to come off the floor. These are the makes behind it.
We service and replace these systems as an independent licensed plumber. We are not an agent for, or endorsed by, any of these manufacturers.
A pipe near the unit or the body of the tank itself. Those two answers lead to completely different visits.
Every unit carries a compliance plate with a date, and we read it out, because a real age turns repair or replace into arithmetic.
Relief valve, anode, element or thermostat where that genuinely solves it. Nothing gets changed over while it has life left.
We run it, check the delivered temperature, take the old unit away and leave you the paperwork.
A licensed plumber answers directly. Repairs are usually same-day and plenty of changeovers are too.
Call 1300 381 569Very often not. A storage system has a temperature and pressure relief valve, and it is meant to release water. As the tank heats, the water expands, and that valve lets the excess go rather than letting pressure build. A small discharge while the unit is heating is the system working correctly.
When it is continuous. A valve that runs steadily rather than occasionally has either failed or is telling you the incoming pressure is too high, and both of those are repairs rather than reasons to replace a tank. It also costs money quietly, because that is mains water going down a drain around the clock.
Because of where the discharge line ends. On a lot of properties around here the unit sits at the side of the house and the line runs down into a garden bed, which is somewhere nobody has a reason to look. A valve can run for months and the only sign is a bill.
That is a different fault, usually a corroding tank or a spent anode. Discoloured hot water with clear cold water points at the cylinder rather than at the supply, and it is worth acting on.
Soft water is why they fail this particular way. In hard-water places a tank silts up with scale. Sydney's supply is not like that, so instead the sacrificial anode is consumed protecting the steel and the tank starts corroding once it is gone, or an element burns out. Both are frequently repairs.
Replace. Water from the body of the cylinder means the steel has gone and there is no patch for that. Shut it off and ring, because the damage compounds daily.
Diagnosis is $120 to $250 and comes off the repair. A relief valve replaced is $200 to $400. An element or thermostat is $250 to $550. An anode is $300 to $600. A storage replacement is $1,400 to $2,800.
Tell us the type, roughly the age, and if there is water, whether it is coming from a pipe or from the tank itself. That last one settles most of it.
Kept if it can be kept, replaced if it cannot, at a figure agreed first.
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