Three questions that decide it
1. Is the tank leaking?
Water coming from the tank body itself, rather than a valve or fitting, means the inner tank has corroded through. There's no repair for that. It needs replacing.
2. How old is the system?
Check the date on the compliance label. Storage tanks usually last 8 to 12 years (see typical lifespans by type). Spending a few hundred dollars on a 12-year-old tank often buys only a short extension before the tank itself fails. On a four-year-old system, the same repair is clearly worth it.
3. What has failed?
Elements, thermostats, relief valves, thermocouples and anodes are all replaceable parts. Heat pump compressors and the control boards on some continuous flow units can cost a large share of a new system, so age matters more for those.
A simple rule of thumb
| Situation | Usually |
|---|---|
| Under 8 years old, valve, element or thermostat fault | Repair |
| 8 to 10 years old, minor fault | Repair, and start planning a replacement |
| Over 10 years old, major part needed | Replace |
| Tank leaking from the body, any age | Replace |
| Parts no longer made | Replace |
When replacement saves money
If your old electric tank is on a continuous tariff, replacing it with a heat pump can cut the power used for hot water substantially, and STC incentives on eligible models reduce the purchase price. Sometimes a working but old system is worth replacing on purpose, on your timeline, rather than in an emergency.
Common questions
Is it worth repairing a 10-year-old hot water system?
Usually only for a minor part such as a relief valve or thermostat. A 10-year-old tank is near the end of its typical life, so for anything major, replacement is usually better value.
How do I find out how old my hot water system is?
Look for the compliance or rating label on the side of the unit. It shows the manufacture date or a serial number that the manufacturer can date.
Sources and further reading
- Business Queensland: hot water systems (temperature control devices on new and replacement systems)
- QBCC: Form 4 notifiable work (installing, replacing or removing a water heater)
- Clean Energy Regulator: solar water heaters and air source heat pumps (STC eligibility)
- Residential Tenancies Authority: emergency and routine repairs