How often should you clean your water tank?

Updated 7 October 2026 · 4 min read

Short answer

Clean an overhead or underground water tank every six months. Make it every three to four months if the water is hard, the supply is irregular or the area is dusty, and clean it straight away if the water smells, looks cloudy or the tank was left open.

Sediment, algae and dust settle in a tank between cleanings, and if the lid doesn't seal or the tank is cracked, insects get in too. Twice a year is the usual rhythm for a home tank.

How the cleaning is done

Drain the tank fully, keeping a bucket or two aside if you need water during the job.
Scrub the walls, floor and corners with a long-handled brush to loosen sludge and algae.
Rinse and drain until the water runs clear.
Disinfect with a bleach or bleaching powder solution, leave it for an hour or two, then drain.
Rinse several times until there's no chlorine smell, then refill.

Many families hire a tank cleaning service, which brings a pump and a vacuum for the sludge. For an underground sump, hiring help is the safer choice. Never climb into a closed tank alone, because the air inside can be unsafe to breathe.

Clean it sooner if

The water smells, tastes odd or looks cloudy.
You can see algae, slime or insects.
The lid was left off or the tank has a crack.
Your water purifier's filters are clogging faster than usual.

Common questions

How often should a water tank be cleaned?

Every six months for a home tank, and every three to four months with hard water, an irregular supply or dusty surroundings. A plastic tank with a lid that seals well can sometimes go longer, but twice a year is the safe default.

Can I clean the water tank myself?

An overhead tank, yes: drain, scrub, rinse, disinfect and rinse again. For an underground sump or a large tank, use a cleaning service, and don't climb into a closed tank alone because the air inside can be unsafe.

Is bleaching powder safe for cleaning a water tank?

Yes, as a disinfecting step, as long as the tank is rinsed several times afterwards until the chlorine smell has gone. Don't refill and use the water straight after disinfecting.

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