Water Tank Size Calculator: Litres Needed for Your Family
Free tool · Updated October 2, 2026 · By CouponTalk
Your result
Enter your measurements to see your result.
Quick answer
Tank size = people × water use per person per day × days of storage. Indian building codes use 135 litres per person per day for homes with flush toilets, so a family of 5 needs 675 litres a day. With one day of storage that rounds up to a 750-litre tank, and a 1,000-litre tank if water supply is irregular.
How to use this calculator
- Count everyone who lives in the house, plus regular guests or staff.
- Pick daily use per person; 135 litres is the standard for city homes.
- Choose days of storage based on how regular your water supply is.
Tank size chart
| People | Daily use (135 L each) | Tank for daily supply | Two days of storage |
|---|---|---|---|
| 2 | 270 L | 500 L | 540 L |
| 3 | 405 L | 500 L | 810 L |
| 4 | 540 L | 750 L | 1,080 L |
| 5 | 675 L | 750 L | 1,350 L |
| 6 | 810 L | 1,000 L | 1,620 L |
| 8 | 1,080 L | 1,500 L | 2,160 L |
| 10 | 1,350 L | 1,500 L | 2,700 L |
These are typical figures for Indian homes. Check the product spec sheet, and ask an electrician or installer before you buy or fit anything.
Frequently asked questions
What size tank for a family of 4?
About 540 litres a day at 135 litres per person, so a 750-litre tank with daily supply, or 1,000 litres for safety.
Is a black or white water tank better?
Lighter-coloured tanks heat up less in summer. Multi-layer tanks with an inner white or food-grade layer stop algae growth.
How often should I clean a water tank?
Clean overhead tanks every 6 months, and after the monsoon.
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