Water tank cleaning: a simple checklist every housing society should follow

Most housing societies in Pune clean their water tanks twice a year. Some clean once. A few do not clean at all until residents complain about taste, smell or stomach upsets. Whichever camp your society is in, here is a checklist that takes the guesswork out of it.

Before the cleaning visit: • Get written quotes from at least 2 vendors — and check if they are ISO certified • Ask whether they bring their own pumps, pipes and disinfectants, or expect you to supply • Confirm whether confined-space safety equipment (gas detectors, harness, PPE) is included • Ask for a sample of the digital service report from a previous job • Schedule the cleaning when residents will use the least water — most societies pick Sunday mornings

On the day of cleaning: • Inform residents 24 hours in advance — most will store a day's water in advance • Drain the tank fully through the outlet — never through the overflow (this floods the terrace) • Watch the team set up safety: PPE, ventilation, gas check before any operator enters the tank • If they enter without these — stop the job. Confined-space accidents are real and have killed cleaners in Pune.

What proper cleaning actually involves: • Manual removal of mud, scale and sediment from the floor (jet cannot reach corners) • High-pressure washing of all walls and the floor — top to bottom • Inspection of the inlet, outlet, overflow and ball-valve assembly • Inspection of the manhole cover gasket — most are torn and let dust in • Food-grade disinfection — the chemical name should be on the bill • Rinse to neutral pH before the tank is refilled

After cleaning — what the report should contain: • Date and time of service • Tank capacity in litres • Photos of the tank before cleaning, mid-cleaning and after • Names of operators and supervisor • Disinfectant used and concentration • Any defects observed (cracks, leaks, missing gaskets) • Recommendations and next-due date

Refill the tank with fresh municipal water. The first 100 litres should be drained from each outlet — that flushes the supply pipes. Residents can use the water normally after that.

How often: every 6 months for most overhead tanks; every 3 months for underground sumps in summer; immediately if there is any change in taste, smell, or colour of the water.

If your society has not had a written cleaning report in the last 12 months, you are overdue.