How to Calculate Rectangular Water Tank Size & Capacity in liters?

For a high rise building, we will receive approved drawings from architect office regarding water tank dimension.

But what if you need to calculate a water tank for a small residential.

In this post, we are going to see how to estimate rectangular water tank capacity & size?

How to Calculate Rectangular Water Tank Size & Capacity?

Volume of Water Requirement

As per IS code,  135 litres is needed for daily use per person per day. Breakup of the IS assumptions

  • Drinking – 5 litres
  • Cooking – 5 litres
  • Bathing & Toilet  – 85 litres
  • Washing Clothes & Utensils – 30 litres
  • Cleaning House – 10 litres

Water Tank Size & Capacity Calculation

For a typical family (4 members),

Total water requirement is 135 litres x 4 = 650 litres per day.

We all know Volume of water formula as 1 m3 = 1000 litres of water.

In order to get the size of the water tank, you need to mention at least one dimension (Length, Width or Depth of the water tank).

If you are planning to construct a water tank in car parking area there may be some restriction on length.

That’s the reason why we are planning to construct the underground water tank while foundation work.

From the above, volume of water formula,

1 m3 = 1000 litres

1 litre = 0.001 m3

Our requirement is 650 litres,

Therefore, 650 litres = 0.65 m3

Assuming our water tank depth as 0.6 m

Water Tank Volume Calculation

Note: you can also replace your input if you know the length,

Water tank depth calculationSo, For 650 litre water tank size, L = 1.47 m, B = 0.74 m & D = 0.6 m

rectangular water tank model

You can also play with the below calculator. If you know the water requirement, just adjust any one of the dimension to meet your requirement

Rectangular Water Tank Litre and Size Calculator

Happy Learning 🙂