A couple in Ingleburn asked me last month whether to keep patching the electric tank in their laundry. It had a new element three years ago, a new relief valve last winter, and now the tempering valve was weeping. I looked at the compliance plate on the side. Manufactured 2009. That's a 17 year old storage tank, and it had already outlived the average by a good margin.
So, how long do hot water systems last? As a rule of thumb: an electric or gas storage tank lasts 8 to 12 years, a gas continuous flow unit 15 to 20, a heat pump 10 to 15, and solar collectors 15 to 20 with a tank that goes at the same rate as any other tank. Water quality, how hard the system works and whether anyone ever checked the sacrificial anode move those numbers a fair bit. The rest of this post is how to find out how old yours is, how to get more years out of it, and how I decide between repairing and replacing. If the shower is cold right now, we are a hot water plumber, no call-out fee, across Liverpool, Campbelltown and Camden.
Electric and gas storage tanks last around 8 to 12 years, heat pumps 10 to 15, and gas continuous flow units 15 to 20. The date is on the compliance plate on the side of the unit. A leaking tank should be replaced at any age; parts like valves and elements are worth repairing on a tank under 8 years old.
How long do hot water systems last, by type
| System type | Typical life | What usually ends it |
|---|---|---|
| Electric storage (mains pressure) | 8 to 12 years | Tank rusts through once the anode is gone |
| Gas storage | 8 to 12 years | Tank corrosion, burner and thermocouple wear |
| Gas continuous flow (instantaneous) | 15 to 20 years | Scale in the heat exchanger, electronics |
| Heat pump | 10 to 15 years | Compressor and fan wear, tank corrosion |
| Solar | 15 to 20 years for collectors, tank as per storage | The tank goes first, the collectors keep working |
A few notes from the tools. Continuous flow units last longer because there's no tank of hot water sitting there corroding, but they're fussier about scale and need their filters cleaned. Heat pumps have a tank like any storage unit plus a compressor like a fridge, and the tank is usually the part that decides it. A storage tank that's been serviced (anode checked, valves replaced) will outlast a neglected one by years. I still see 20 year old tanks working. I also see 7 year old ones rusted out because nobody ever looked at the anode.
Hot water system age: how to read the compliance plate
You don't need to guess. Every unit has a compliance plate (a rating plate, a data plate, the sticker on the side) with the make, model, capacity in litres, and either a date of manufacture or a serial number that encodes it. On most Australian brands the plate says it outright or the serial number starts with the date. If the plate has faded, the brand's website usually explains how to read the serial. Take a photo of it; it's the first thing I ask for on the phone.
The other clues
If the plate is gone, look at the installation. A tank with a modern tempering valve on the hot outlet and a relief valve drain line run to a proper outlet is a reasonably recent install. Older tanks around Fairfield often have no tempering valve at all, which tells me they went in before that requirement, and that they're overdue. The compliance certificate from the last installation, if you can find it, has the date on it too.
The sacrificial anode: the cheapest years you'll ever buy
Inside every glass-lined steel storage tank there's a magnesium or aluminium rod hanging from the top. It's there to corrode so the tank doesn't. Water attacks the anode before it attacks the steel, and once the anode is eaten away, the tank is on the clock. Checking it is a short job for a plumber with the water off: unscrew it from the top, pull it out, look. If it's down to the wire, it gets replaced. The common advice from manufacturers and plumbers alike is a check somewhere around the 5 year mark, earlier in areas with harsh water. I'd rather do it at 5 and again at 10 than replace a tank at 8. If your system is under 8 years old and nobody has ever looked at it, this is the single best thing you can do for it. It's quoted on inspection, because anode types and access vary.
Signs your system is on the way out
These are the ones that make me say replace rather than repair. Rusty or brown hot water from every hot tap (not just the first few seconds) means the tank lining is gone. Water weeping from the base of the tank, or a rust stain on the concrete under it, means the cylinder has failed, and there is no repair for that. Rumbling and popping as it heats is sediment cooking on the bottom, which shortens its life and costs you on the bill. Hot water that runs out faster than it used to, or never gets as hot, is often an element or thermostat, but on an old tank it's a warning. And a relief valve that gets replaced and starts running again is usually pressure or a failing tank. I've written a whole post on a hot water system leaking if that's where you are now.
Repair or replace: how I decide
This is the honest rule I use. If the tank itself is leaking, replace it, whatever the age. If the system is under 8 years and the problem is a valve, an element, a thermostat, a thermocouple or a hose, repair it: those are parts, and the tank has life left. If the system is over 10 years and the repair is more than a valve, I'll tell you to put the money towards a hot water system replacement instead, because you'll be doing it within a couple of years anyway and you'll have paid twice. Between 8 and 10 it's a judgement call on the tank's condition, the water where you are, and whether a renovation is coming up. If one is, a renovation is the right time to move the tank, upsize it or go to a heat pump, and I'd rather plan that than replace it in a hurry in July.
One more thing to know. A new storage system installed in NSW has to have a tempering valve limiting bathroom hot water to 50 degrees, it's licensed work, and it ends with a compliance certificate. That's part of why a like-for-like changeover on an old install sometimes costs more than people expect: the valves and pipework get brought up to standard at the same time.
How much to replace a hot water system in Sydney
For hot water system replacement cost, Sydney 2026 price guides put an electric storage system installed at $920 to $2,875, gas storage at $1,375 to $4,025 and a heat pump at $3,450 to $6,900 before rebates. The rebates are worth knowing about if you're replacing an electric or gas tank: roughly $900 to $1,350 off between federal STCs and the NSW hot water upgrade incentive, with a minimum $220 co-payment and the work done through an accredited provider. Continuous flow is quoted on inspection, because the gas line sizing and where it mounts make a big difference. What moves any of these numbers: whether it's like-for-like on the same spot, the size of the tank, how much of the old pipework and valves can stay, and whether it's an after-hours emergency. I break it all down in hot water system installation cost in Sydney.
When to call a plumber
Call now if the tank is leaking from the body, if there's water near the switchboard or the element cover, or if you've got no hot water and the breaker isn't the answer (run through no hot water? what to check first). Call during business hours to have the anode checked, to get an age check and an honest opinion on an older unit, or to plan a replacement before it fails on the coldest morning of the year. A tank that's still holding water is not an emergency, and I'll say so rather than make a night call-out of it. Done right. Done once.
Monarch Civil & Plumbing covers South West Sydney and the Macarthur region for hot water system repairs and replacements, from Liverpool to Camden, with 24/7 emergency call-outs for the ones that can't wait. If you need a plumber in Ingleburn, a plumber in Camden or anywhere in between, call 0455 222 292 with a photo of the compliance plate and I'll give you a straight answer on repair or replace.
Related guides: hot water system installation cost and hot water system leaking.
Need it sorted? Ring 0455 222 292 any hour or book online. Monarch Civil & Plumbing is a hot water plumber, no call-out fee: repairs where they are worth it, same-day replacement where we can, and the NSW rebate sorted.
No hot water in Campbelltown, Liverpool or Camden?
Campbelltown has its own page: hot water service Campbelltown. For Liverpool, Camden and the rest of South West Sydney start with hot water systems, then the suburb pages plumber Liverpool and plumber Camden. Same-day replacement for common electric and gas sizes where stock allows, no call-out fee, NSW rebate sorted for heat pumps.
Frequently asked
How long does a hot water system last on average?
Storage tanks, electric or gas, last 8 to 12 years on average. Gas continuous flow units last 15 to 20 years because there's no tank to corrode. Heat pumps sit around 10 to 15 years, and solar collectors 15 to 20 with a tank that lasts like any other tank. Anode checks, moderate mains pressure and good water quality push you toward the top of those ranges.
How do I find out the age of my hot water system?
Look at the compliance plate, the metal plate or sticker on the side of the unit. It shows the make, model, capacity in litres and either the date of manufacture or a serial number that encodes it. Most brands explain their serial format online. If the plate is unreadable, the style of the installation and the compliance certificate from the last install are your next best clues.
What does a sacrificial anode do and how often should it be replaced?
The anode is a magnesium or aluminium rod inside the tank that corrodes in place of the steel. Once it's used up, the tank starts rusting from the inside. The usual advice is to have it checked at around 5 years and replaced if it's worn, earlier in areas with harsh water. It's a short job with the water off and the best value maintenance you can do on a storage system.
Is it worth repairing a 10 year old hot water system?
It depends on the fault. A valve, element, thermostat or hose on a tank that's otherwise sound is worth fixing at almost any age. A leaking tank is not repairable at any age. Past 10 years, if the repair is more than a simple part, the money is usually better spent on a replacement, because the tank is near the end of its life and you'd end up paying twice.
How much does it cost to replace a hot water system in Sydney?
Sydney 2026 price guides put electric storage at $920 to $2,875 installed, gas storage at $1,375 to $4,025 and a heat pump at $3,450 to $6,900 before rebates of roughly $900 to $1,350. Continuous flow is quoted on inspection. Like-for-like on the same spot sits at the bottom of the range; a change of fuel or location, or an after-hours job, pushes it up.
Can a hot water system last 20 years?
Some do, especially continuous flow units and well maintained storage tanks in areas with good water. I still see the odd 20 year old tank going strong. But by that age a storage tank is running on borrowed time, spare parts get harder to find, and it uses more energy than a new unit. Plan the replacement rather than waiting for it to fail on a cold morning.
Licensed plumber and drainer based in Austral, 13+ years in the trade, working across Liverpool, Fairfield and the Macarthur region. About Paul