Start with the fault, not the age
Age alone does not decide the question. What matters first is which part has failed. A tank that has corroded through cannot be repaired, regardless of how old the unit is. A failed thermostat on a five-year-old system is a routine repair.
| Symptom | Likely cause | Usual outcome |
|---|---|---|
| Water pooling under the unit | Internal tank corrosion | Replace |
| Constant discharge from the relief valve | Faulty valve or high mains pressure | Repair |
| No hot water, electric system | Element or thermostat | Repair |
| No hot water, gas system | Ignition, thermocouple or gas valve | Repair, subject to parts |
| Rusty hot water only | Tank corrosion or failed anode | Assess, usually replace |
| Rumbling during heating | Sediment build-up in tank | Assess, often nearing end of life |
When replacement is the practical answer
- The tank is leaking, not the fittings around it
- The system is past its expected service life and has failed again
- Repairs in the last two years already add up to a substantial figure
- Parts for the model are no longer readily available
- The system is undersized for how the household now uses hot water
When repair makes sense
If the tank is sound and the failed component is a standard serviceable part, repair is normally the sensible option. That is particularly true where the unit is still within its warranty period, because the manufacturer may cover the part.
Before spending anything, photograph the data plate on the side of the unit. It carries the model, capacity and manufacture date, which is the fastest way to establish age and warranty status.
The cost comparison that actually matters
Compare the repair cost against the remaining useful life of the system, not against the full price of a new installation. Spending a moderate amount on a system with several years left is reasonable. Spending the same amount on a unit already at the end of its life usually is not.
What to do right now if it has failed
- If water is escaping, isolate the cold supply to the unit or turn off the water at the meter
- Switch off power to an electric system at the switchboard, or close the gas isolation valve on a gas unit
- Photograph the unit, the data plate and the surrounding installation area
- Call a plumber with those details ready so the advice can be specific