I currently have a 750 litre overhead water tank installed. Is it possible to install a 5000 litre water tank in the same place? Would the weight be a concern? The house is a two storied buliding bulit on a 1200 square feet site. The total height of building is about 23 feet. Thanks beforehand.

  • 2
    So you want to replace a tank that weighs about 1000kg with one that is 5 times heavier? Get it checked by an architect or engineer.
    – Solar Mike
    Commented Aug 16, 2020 at 10:34
  • 2
    Closer to 7 times heavier (the contents 6.667 and then the empty tank will weigh more too.) You could very easily go from 23 feet / 7 meters high to a pile of rubble a few feet/meters high, with loss of life. Definite need for a structural/civil engineer assessment. A safer alternative might be a ground level tank for more storage and a pump to the existing tank.
    – Ecnerwal
    Commented Aug 16, 2020 at 11:11

2 Answers 2


You need a structural engineer. There is no way for us to judge the stability of your roof


750 litres weighs -- well I'll spare you the gory math as it would make the answer too long, but it comes out to 750 kilograms or 1650 pounds. Or the weight of a small car.

Now I wouldn't put that on my roof without architectural review.

Now, you propose to put a 5000 litre tank there, which is 5000 kilograms (11,000 lbs). Or the weight of a semi tractor.

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So no... even the 750l tank is a risk. You need an engineer to certify and/or reinforce the building.

  • but, without an overhead tank, can we get running water for daily use? I think every office or residential building should have an overhead tank
    – vidyarthi
    Commented Aug 17, 2020 at 6:47
  • 1
    @vidyarthi Just have a competent engineer either certify the building or reinforce it. Alternately you can make the tank smaller or use several small tanks. A 100l tank weighs about the same as a human, you can have several spread out and connect the bottoms; they'll act like one big tank. A smaller tank just means needing to refill more often. If on-site storage is an issue, the big tank could be downstairs. Flush toilets and wash water are a huge boon to survival and quality of life esp. children, but it defeats the purpose if the building falls on your head. Commented Aug 17, 2020 at 15:36

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