Find the right water tank size in 30 seconds

What size water tank do I need?

Allow 135 litres of water per person per day. For an overhead tank, buy about 1.5 times the daily need, so the house does not run dry when supply is late. This is how we size tanks at Raja Industrials in Chennai.

People at home	Water used per day	Overhead tank
1-2 people	135-270 litres	500 litres
3-4 people	405-540 litres	1000 litres
5-6 people	675-810 litres	1500 litres
7 or more people	945 litres or more	2000 litres or larger

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What size sump do I need?

A sump, or underground tank, should hold 2 to 3 days of water as a buffer.

Building	Sump size
Single home, 3-4 people	1000-2000 litres
Single home, 5 or more people	2000-3000 litres
Small apartment, 4-8 units	6000 litres
Larger building, more than 8 units	10000 litres or more. Check it against your structural plan first.

What size loft tank do I need?

Backup for	Loft tank size
One bathroom	100-150 litres
Kitchen and bathroom	225-270 litres
A whole floor	300-500 litres

Should I replace my water tank?

Bad smell or yellow water: clean the tank first. Clean it every 6 months. Replace it only if the problem comes back straight after cleaning.
Cracked or leaking: replace it. A patch on a plastic tank fails quickly.
Yellowing on the outside: this is usually only sun damage to the surface. Replace the tank if it has cracks, the water stays poor after cleaning, or it is over 15 years old.
Water runs out: compare your tank with the table above. If it is big enough, the problem is supply, such as a low borewell, a slow pump or short metro water timings. A bigger tank will not fix that.

Should I repair or replace my pump?

Pump age	What we advise
Under 3 years	Rarely needs replacing. It is usually an electrical fault, such as the capacitor, MCB or wiring.
3-7 years	Probably repairable. Replace it only if the motor windings have gone or parts are no longer made.
8-12 years	A judgement call. A capacitor is worth doing, but a rewind near 12 years usually is not.
Over 12 years	It has done its job. Replace it, and check the right pump for your water level and building today.

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Checking a tank in a new home

Weight: 1000 litres of water weighs 1000 kg, so the platform must be built to carry it.
Genuine tank: look for the ISI mark, a food-grade label, and the brand name moulded into the tank body, not only on a sticker.
Dry running: ask for a float switch or dry-run protector. A pump that runs dry damages the motor quickly.

Porul Store by Raja Industrials has supplied water tanks and pumps to Chennai since 1984. We are authorised distributors for Sintex, Vectus, Texmo and Aquatex.

No 10, (26), Errabalu Chetty Street, Parrys, Chennai, Tamil Nadu 600001. Phone +91 44 2522 3260.

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