Sump pump maintenance: how to test and look after yours

Test it yourself, twice a year

Do the test in autumn, before the wet months, and again in spring.

• Pour clean water into the sump until the float lifts.
• The pump should start promptly, clear the water and stop cleanly.
• Watch for a pump that starts and stops repeatedly — usually a float or non-return valve issue.
• Check the discharge point outside is actually running and not frozen or blocked.
• If nothing happens, check the supply and RCD before assuming the pump is dead.

Annual service checklist

• Clean silt, grit and debris out of the sump — abrasive silt is what wears impellers out.
• Inspect and free the float switch; check the set levels.
• Check the non-return valve seats properly.
• Inspect the discharge run for leaks, sags and blockage.
• Test running current against the rated figure.
• Check any alarm or telemetry, and the battery backup if fitted.

Do you need a second pump or a battery backup?

If a basement holds anything valuable — a plant room, stock, a habitable room, a server — the honest answer is yes. Two failure modes account for nearly every flood: the pump dies, or the power goes off.

A twin-pump arrangement covers the first. A battery backup or generator feed covers the second. Storm-related power cuts and heavy rain arrive together, so the two risks are not independent.

Signs a sump pump is on the way out

• Running for longer than it used to for the same amount of water.
• Noisy, rattling or vibrating operation.
• Cycling on and off rapidly.
• Visible rust or silt build-up in the chamber.
• Tripping the RCD or breaker.