Guide · 4 min read
Repair or replace: what decides it for an old hot water system
Repair or replace a hot water system? A leaking tank, rusty water or hot water that runs out early: which faults are a part, and which mean a new tank.
Published · Updated
By Jamie Vesey, licensed plumber and gas fitter
- Contractor licence QBCC 15090309
- Plumber's licence PD56245
- Gas work licence L91819
In this article
Most hot water faults are in a part that can be swapped, which makes them worth repairing. One fault is different: a tank that leaks from its body.
Faults that are usually worth repairing
- A relief valve that drips constantly. The valve is a replaceable part.
- An electric system with no hot water at all. The cause is often an element or a thermostat.
- Water that never gets past lukewarm, or runs out part way through a shower.
- A gas system whose pilot will not stay lit. This one is for a licensed gas fitter, not for a home fix.
A plumber can tell you which part has gone, and you get a written price before any work starts.
Signs the tank itself is finished
- Water pooling under the tank, not at a pipe or valve.
- Rusty or brown water from the hot tap only. If the cold tap runs clear, the rust is coming from the cylinder.
- A tank past its warranty, where a repair may only buy a little time.
- Repeat faults. A second major repair within a short time on an old tank is usually the sign.
A corroded cylinder cannot be repaired at any age. Once water is coming through the wall of the tank, the choice is which replacement to fit.
How age changes the answer
Tank type and warranty are a better guide to age than a number of years. CHOICE says mild steel tanks usually carry 5- to 10-year warranties and can corrode over time, while stainless steel tanks generally last longer and need less maintenance. Check the warranty first: a failed part on a system still covered is the easy case. On a tank well past its warranty, a large repair is harder to justify, and a leak from the tank body ends the question on any hot water system. The date the tank was made is on a sticker or plate on its side.
| Tank or part | What the source says | What to do |
|---|---|---|
| Mild steel tank | CHOICE says it usually comes with a 5- to 10-year warranty and can corrode over time. | Check the warranty date, then ask when the anode was last replaced. |
| Stainless steel tank | CHOICE says it generally lasts longer, needs less maintenance, and usually carries a 10-year warranty. | Check the warranty date. It still needs occasional upkeep. |
| Anode | CHOICE says to have a plumber replace the anode every five years, or as the manufacturer instructs, and that this can add years to the life of the tank. | Ask for the anode to be checked before judging the tank. |
| Valves and seals | CHOICE lists replacing valves and seals as occasional upkeep, and says they often carry only a one-year warranty. | A failed valve or seal is a part fault. Ask for it to be replaced on its own. |
| Your own system | Rheem says its warranty terms are in the Owner's Guide supplied with the product, and may differ for an older water heater. | Find the guide, or the model plate, before you decide. |
Gas hot water: call a licensed gas fitter
Gas hot water faults are a job for a licensed gas fitter. Do not try to relight, adjust or open up a gas system yourself. A gas system may need gas fitting work as well as plumbing, and the fitter should hold the gas work licence for it.
Before you agree to a replacement
- Get the price in writing, including removing the old system.
- Ask what type of system the quote is for, and why it suits your household.
- Ask what the manufacturer's warranty covers, and what the installer's workmanship covers.
- Ask whether the new system needs changes to pipework, the electrical supply or the gas supply.
- Ask for the paperwork once the job is finished.
Electric, gas, heat pump and solar systems each have different install requirements, so the right choice depends on the house. Ask your plumber to explain the options for yours rather than quoting the one system.
Who can do the work in Queensland
The QBCC lists installing or replacing water heaters, including electric, gas, solar and heat pump, as notifiable work. Notifiable work needs no local government permit. The plumber registers it with the QBCC on Form 4 within 10 business days of invoicing, so ask for your copy. The QBCC guide for licensees lists water heaters in the same way, and says a plumber working on a gas water heater also needs the relevant gas licence.
If the fault is a part, see hot water repairs. If the tank has gone, you get a written price for hot water system replacement before any work starts.
Written by
Jamie Vesey, licensed plumber and gas fitter
Jamie Vesey is the licensed plumber and gas fitter who comes to the door at Vesey Plumbing Solutions. He looks after homes, rentals, strata and businesses across the Gold Coast, from the coastal suburbs to the hinterland. He works from blocked drains and hot water to gas fitting and renovation plumbing. He finds the cause first and writes the price down before any work begins.
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