Hot water runs out quickly
moderate 30–90 min
Tools: garden hose, bucket, screwdriver, multimeter (electric)
Steps
- Check the thermostat setting first; on electric tanks there are two, behind the upper and lower access panels, and both should match.
- Flush the tank: switch off power or set gas to pilot, close the cold inlet, connect a hose to the drain valve, open a hot tap upstairs, and drain until the water runs clear. Sediment on the bottom steals capacity.
- Electric tanks: if the lower element has failed you get a short burst of hot water then cold — test the element with a multimeter (it should read 10–16 ohms) or have it tested.
- Look for a broken dip tube: white plastic bits in tap aerators mean cold water is short-circuiting to the outlet.
- Count the demand: two showers plus a dishwasher on a 150-litre tank will always run out — stagger use or plan a larger or tankless unit.
Stop and call a pro if
- the drain valve will not close after flushing
- the lower element or thermostat has failed and you are not comfortable working inside the heater's wiring
- the tank is over 10–12 years old and rusty water comes out during the flush
What a pro does that you can't
A technician replaces the lower element, thermostat or dip tube in one visit, flushes stubborn sediment, and sizes a replacement tank or tankless heater to the household.
DIY cost: $0–35 for a hose, an element or a dip tube