Size your overhead tank to hold about one day of water. This guide gives the per-person figures and a sizing table you can use directly.
A common planning figure for domestic use is roughly 135 litres per person per day. For a family of five, that's around 650–700 litres a day for normal use. Your tank should comfortably cover at least a full day's needs, with a margin for guests and supply interruptions.
| Household | Daily use (approx.) | Overhead tank | Underground sump |
|---|---|---|---|
| 2 people | ~270 L | 500 L | 1000 L |
| 4 people | ~540 L | 500–750 L | 1500–2000 L |
| 5 people | ~675 L | 750–1000 L | 2000 L |
| 8 people | ~1080 L | 1500 L | 3000–5000 L |
| Small apartment block (20 flats) | ~10,800 L | 5000–10,000 L | 20,000 L+ |
For a typical home, size the overhead tank to hold about one day of usage, and an underground sump to hold two to three days as a buffer against supply cuts. So a family of five might use a 500–1000L overhead tank with a larger underground sump. Larger families and buildings scale up from there.
Overhead tanks supply water by gravity and are easy to install; underground tanks store larger volumes and protect against supply interruptions but usually need a pump. Many homes use both together.
Look for multi-layer tanks with a UV-resistant outer layer and an anti-bacterial inner layer to keep water clean and the tank durable in the sun. Tell us your family size or project details and we'll recommend the right capacity and type.
A common planning figure for domestic use in India is roughly 135 litres per person per day, covering drinking, bathing, washing and cleaning. Actual use varies with lifestyle and season.
At roughly 135 litres per person per day, a family of five uses about 675 litres a day. A 750–1000 litre overhead tank with a larger underground sump is a common setup, leaving margin for guests and supply cuts.
Overhead tanks supply water by gravity and are simple to install. Underground sumps hold much larger volumes and buffer against supply interruptions, but need a pump. Many homes use both together.
Look for multi-layer construction with a UV-resistant outer layer and an anti-bacterial inner layer, which keeps the water clean and helps the tank last in direct sun.
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