Four signals that say “replace”
- Visible rust around the tank seam or the inlet/outlet ports. Once corrosion reaches the steel of the tank, you are on borrowed time. A patch is a stop-gap, not a fix.
- Rusty water from the hot tap only. Run the cold tap first; if cold is clear and hot is brown, the rust is inside the tank.
- Rumbling, banging or popping noises as the heater warms. Heavy sediment at the bottom of the tank. Sometimes a flush extends life, but if the unit is over eight years old, a replacement is usually the better spend.
- Heater is more than ten years old (storage) or eight years old (instant) and needs any non-trivial part. The cost-per-remaining-year favours replacement.
Two signals that say “just service”
- Hot water runs out faster than it used to. Often a thermostat or heating element issue — both are inexpensive on a young storage tank.
- Slow drip from the T&P (temperature & pressure) safety valve. This valve is designed to weep under thermal expansion; if your home does not have an expansion tank, a small drip is normal. We can advise whether to fit one.
The cost-versus-life maths, made simple
Take the estimated repair quote and divide by the years of remaining life you can reasonably expect. Then take the price of a fair replacement (unit + install) and divide by 10 (storage) or 8 (instant). If the “repair per year” is more than half the “replace per year”, replace it.
This is exactly the calculation we do for our customers on the spot. It removes emotion from the decision.
What a proper install includes
- Inlet and outlet ball valves, so the next service does not need a whole-house shut-off.
- A new T&P safety valve with a discharge pipe to a safe drain point.
- A drip tray (for storage units installed above a finished ceiling).
- Earth bonding checked and confirmed.
- A label on the unit listing install date and isolation point. The next plumber will thank us.
What we will not do
We will not upsize you to a 60L tank if your hot-water habits fit a 35L. The larger unit costs more, heats more water you do not use, and adds a small standing electrical cost every month for the rest of its life. Pick the size that fits the household, not the showroom display.