How to Clean a Sintex Water Tank

Understand your tank first

Sintex is a brand name, but in Delhi NCR people use it for most rotomoulded plastic tanks. These tanks are typically made from polyethylene in layers: a dark outer layer to block light and UV, and an inner layer in contact with the water. The inner surface is smooth when new — and keeping it smooth is the key to a tank that stays clean longer. Scratches give biofilm and sediment somewhere to grip.

What you'll need

• Soft-bristled brush or sponge on a long handle.
• Buckets, a mug or a wet-dry vacuum.
• Rubber gloves and non-slip shoes.
• A helper.

Don't use: wire brushes, steel wool, sandpaper, scouring powder, acids, phenyl, toilet cleaner or kerosene. They scratch or chemically attack the plastic, and residues can taint the water.

Step-by-step

1. Switch off the motor and close the inlet. Store water in buckets for a few hours.
2. Use up the water through taps until only the bottom few inches remain — that's where the sediment is.
3. Scoop or vacuum the sludge out into buckets. Don't flush it down the outlet.
4. Scrub gently with a soft brush and clean water — walls, floor, corners and the underside of the lid. Use circular motions on stained areas rather than force.
5. Rinse and remove the rinse water. Repeat until clear.
6. Disinfect if needed using a product intended for drinking water, at the label dose and contact time, then rinse well. See our chemicals guide.
7. Close the lid securely, reopen the inlet and run taps briefly after refilling.

Removing green algae from a plastic tank

Green patches on the walls mean light is getting in. Scrub them off with a soft brush, then deal with the cause: replace a cracked or ill-fitting lid, shade the tank, or replace a faded tank whose outer layer no longer blocks light. Our guide on removing algae goes further.

Getting into a larger tank

For tanks above about 1,000 litres you'll usually need to climb inside to scrub properly. Doing that on a rooftop platform is risky, and the tank can flex under your weight. This is where a professional Sintex tank cleaning makes sense.

Keeping a plastic tank cleaner for longer

• Keep the lid tight. Replace warped or cracked lids — they're inexpensive.
• Fit mesh on overflow and vent pipes.
• Keep the sump clean, since it feeds the tank.
• Inspect the outside: chalky, cracking or bulging plastic means the tank is ageing.

How often?

Every six months for most homes; every three to four months if the tank is in full sun, translucent, or fed by tanker or borewell water.

Preventing algae in a Sintex tank

Algae needs light. Keep the lid closed and in good condition, shade the tank if it's in full sun, and replace a tank whose walls have faded so much that light passes through. Clean every 3–4 months in summer.