7 signs your water tank needs cleaning

What you notice at the tap

The water in your taps is only as clean as the tank it sits in. Since nobody looks inside a rooftop tank or an underground sump very often, the first clues usually show up in the kitchen or bathroom.

1. A smell. A musty, earthy or "rotten egg" smell when you open a tap, especially first thing in the morning, often means organic matter is breaking down in the sludge at the bottom of the tank.
2. Yellow, brown or cloudy water. Fill a clear glass or a white bucket and hold it to the light. A tint, or water that takes a while to settle, usually points to silt lifting off the tank floor.
3. Grit or particles. Fine sand at the bottom of a bucket, or tap aerators and shower heads that clog quickly, are a classic sign of a thick sediment layer.
4. A slimy feel or film. If the inside of buckets, the washing machine drawer or the RO pre-filter turns slimy or greenish, algae or biofilm may be growing in the tank.

What you see in and around the tank

You do not need to go inside to check. Open the lid of a rooftop plastic tank and use a phone torch. For an underground sump, look in from the manhole only; never lean in or climb down.

5. Green or black patches on the walls. Algae shows up as green streaks near the waterline and under the lid, especially after a hot summer. Black spots can be mould or old deposits.
6. A visible layer on the floor. If you can see a brown or black layer at the bottom, or the water turns murky when you stir it with a long stick, the sludge is overdue for removal.
7. Lower pressure or air in the lines. Thick sludge can partly block the outlet pipe and the motor's foot valve, so pressure drops or the motor sputters. Not every pressure problem is a dirty tank, but it is worth ruling out.

Other reasons to clean even if the water looks fine

Clear-looking water is not proof of a clean tank. Book a cleaning anyway if:

• It has been more than 6 months since the last cleaning, or you do not know when it was last done.
• You have just moved into a new flat or house.
• A bird, rat, lizard or insects got into the tank.
• The lid was left open, or blew off in a storm.
• The monsoon has just ended and supply water was muddy for weeks.
• Someone at home has had repeated stomach upsets and you want to remove the tank as a possible factor. Please also see a doctor; a clean tank is not a substitute for medical advice.

Our guide on how often to clean a water tank in Gurugram explains why 6 months is a sensible routine.

Rooftop tank or sump: which one is the problem?

A simple test: run the motor and fill a bucket from the pipe where sump water enters the rooftop tank, then compare it with water from a tap. If both look dirty, the sump is likely the source. If only the tap water looks bad, the rooftop tank itself needs attention. In practice we usually recommend cleaning both together, because sludge in the sump keeps refilling the rooftop tank. See our overhead tank cleaning and underground sump cleaning pages for how each is done.

If the smell is strong, or water looks very discoloured, it is sensible to avoid drinking it until the tank has been cleaned and the water replaced.

Spotted one or more of these signs? Send your tank sizes and sector through the free quote form. We reply on WhatsApp with a fixed quote including GST, share before and after photos of the job, and you pay only once you are happy.

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