How long a geyser lasts in hard water, and how to double it

Geyser life is mostly a function of water. The same unit that runs a decade on a soft municipal supply can be scaled solid and leaking in four or five years on hard groundwater. That gap is not bad luck. It is maintenance.

What hard water does

Every litre heated leaves a little calcium and magnesium behind. It coats the element, so it runs hotter to do the same work and eventually burns out. It settles in the tank bottom and holds heat against the steel, which corrodes faster. It consumes the anode rod ahead of schedule.

The three habits

• Descale every year, before winter. A scaled element is the single biggest reason geysers die early here.
• Check the anode rod every two years and replace it when it is more than half gone.
• Keep the thermostat at 55 or below. Scale forms far faster above 60.

Signs it is being shortened

Taking longer to heat than it used to. A knocking or crackling while heating. Rust in the first draw. A rising electricity bill with no change in use. Each is scale or the anode, and each is reversible if caught.

If a geyser is more than six years old in a hard-water home and has never been descaled, have it inspected before spending on a repair. Sometimes the honest answer is that the tank is near its end and a new unit with a maintenance plan is better value.

The arithmetic

An annual descale costs a fraction of a geyser. Doubling the life of the unit is the return. It is one of the few maintenance jobs where the maths is that clear.