Hot water systems almost never die at a convenient moment. They go on a Sunday, or the morning you have somewhere to be, and suddenly you are making a decision about a fairly expensive appliance while standing in a cold shower.
It is a much better decision if you have thought about it beforehand. Here is how to work out where yours is up to.
How long should a hot water system last?
It depends on the type, but as a rough guide:
- Electric and gas storage tanks: around 8 to 12 years
- Continuous flow gas: around 15 to 20 years
- Heat pump and solar: around 10 to 15 years, though the tank and the components often age at different rates
Brisbane water is reasonably kind to hot water systems compared with harder-water parts of the country, but the sacrificial anode inside a storage tank still does its job and still wears out. If a tank has never had its anode checked and it is past about eight years, the tank is on borrowed time whether it is leaking yet or not.
The warning signs
Rusty or discoloured hot water
If the hot runs brown or rusty and the cold runs clear, that is coming from inside the tank. It usually means the anode is spent and the tank itself has started to corrode. Once a steel tank is rusting from the inside there is no repair for it.
It runs out much faster than it used to
Sediment builds up in the bottom of a storage tank over the years and takes up volume that used to hold water. A tank that gave you two comfortable showers and now manages one and a half has not shrunk, it has silted up.
Banging, popping or rumbling
That is water boiling underneath a layer of sediment. It is not immediately dangerous but it means the system is working harder and less efficiently than it should, and it is a fair sign of age.
Water around the base
A small amount of water from the relief valve is normal, particularly on a hot day. A steady pool underneath the unit is not. A leaking tank is a replacement, not a repair.
The temperature keeps changing
Hot then cold then hot again, particularly on a continuous flow unit, usually points to a failing component rather than a failing system. This one is often genuinely repairable, which is why it is worth having someone look before you assume the worst.
Repair or replace?
The honest rule of thumb we use is this. If the tank itself is sound and the problem is a component, such as an element, thermostat, valve or igniter, repair is usually the sensible option. Those parts are replaceable and the rest of the unit still has life in it.
If the tank is leaking, rusting, or is past its expected lifespan and needing its second or third repair, you are spending money to delay a replacement you are going to make anyway. At that point putting the same money toward a new system usually works out better.
What we will not do is tell you a repairable system needs replacing. There is no head office setting sales targets here, so nobody has a reason to sell you a tank you do not need.
The safety bit most people do not know about
Two numbers matter, and they seem to contradict each other until you understand why.
Under AS/NZS 3500.4, a storage system has to keep water at a minimum of 60°C. That is not about comfort, it is to stop Legionella bacteria establishing in the tank.
But water at 60°C will scald a child in seconds. So the same standard requires that water delivered to bathroom fixtures does not exceed 50°C, and 45°C in settings like aged care, childcare and schools.
The part that reconciles those two numbers is the tempering valve. It blends the stored 60°C water down before it reaches your tap. If your system is being replaced and there is no tempering valve fitted, or the existing one is past it, that gets sorted as part of the job. It is not an optional extra.
The paperwork nobody mentions
Replacing a hot water system is classified as notifiable work under the Plumbing and Drainage Act 2018 (Qld). That means the licensed plumber who does it has to register it with the Queensland Building and Construction Commission on a Form 4 within 10 business days of invoicing.
This matters to you for two reasons. It is your evidence the work was done by someone licensed and done to code, and it is the sort of thing that gets asked about when you sell. If a quote seems unusually cheap, it is worth asking whether the person quoting intends to lodge it.
Planning ahead beats an emergency
If your system is over eight years old and showing any of the signs above, get it looked at while you still have hot water and time to compare options. You will make a better decision than you will at 6am on a Sunday.
We handle repairs, replacements and new installations for hot water system repairs and replacement in Brisbane, including electric, gas, solar and heat pump. If the unit is gas, we can look after the gas appliance installation and certification side at the same time. Call 0487 037 290.
