What Size Water Tank Do You Need? A Guide for Sri Lankan Homes

Short answer: plan on roughly 150 to 200 litres per person per day, plus a margin for supply cuts. For most Sri Lankan families of four to six, a 1000 L tank is the right size. A small household or an annexe takes 550 L; three or four people take 750 L; a large household, guest house or shop takes 2000 L.

The sizes we stock

Stocked in S-Lon and Arpico Hybrid, in the Plumbing section.

Check the structure before you order

A filled 1000 L tank weighs about a tonne, and it sits on a small footprint. Before ordering, make sure the roof slab or the stand can carry it. This is the check people skip most often, and it is the one that matters most — if there is any doubt, have a mason look at it first.

Hybrid or plain?

Arpico Hybrid tanks use several wall layers. The practical difference is that sunlight does not get through, and light is what lets algae grow in stored water. The multi-layer wall also takes knocks better. A plain single-layer tank costs less; a hybrid keeps the water cleaner for longer under Sri Lankan sun.

Practical points worth knowing

• The lid matters. A poorly fitting lid lets in dust, insects and light — all three shorten how long stored water stays clean.
• Leave access all round. A tank pushed hard into a corner cannot be cleaned properly.
• Clean it twice a year. Sediment settles at the bottom and the outlet sits above it, so a tank can look fine from the tap and still be dirty inside.
• Two smaller tanks can beat one big one where access is tight — and you can clean one while the other stays in service.

Getting it delivered

Tanks travel by lorry, not by courier, so transport is quoted with the order. Tell us the size and the town and we will give you a delivered price — send it through Request a Quote or call us. If you are also fitting a pump, read our guide on how to choose a water pump.

Common questions

What size water tank is best for a family of four?

1000 litres is the usual choice for four to six people. It covers normal daily use with enough left over to ride out a supply cut of a day or so.

How much does a 1000 litre water tank weigh when full?

About one tonne. The empty tank is light — it is the water that has to be carried by the slab or the stand, on a fairly small footprint.

Is a hybrid water tank worth the extra?

If the tank sits in direct sun, yes. The multi-layer wall blocks light, which is what stops algae growing in the stored water, and it stands up to knocks better than a single-layer tank.

Can I put a water tank on my roof slab?

Only if the slab was built to carry it. Check with a mason or engineer before ordering — a filled 1000 litre tank is about a tonne concentrated on a small area.

Need help choosing? Call +94 71 302 4843, message us on WhatsApp, or send your list through Request a Quote. WPL Trading, No. 305, Kandy Road, Dummaladeniya, Warakapola — open every day, 9.00 a.m. to 6.30 p.m., with island-wide delivery.

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