# Measuring a Water Tank for a Replacement Liner

All that is needed to work out the size of the tank liner is the internal diameter (d) of the tank and the height (h) of the inside of the tank.

You can also use these measurements to calculate the volume of your water tank. This example assumes you are measuring in meters.

Calculating the volume of your water tank:

p x (d/2) x (d/2) x h where p is pie = 3.14159

so for a 2 m high tank with a diameter of 5 m, the volume is them

= 3.14159 x (5 ÷ 2) x (5 ÷ 2) x 2 = 39.27 m3

The amount of water that can be held is then 39.27 x 1000 = 39,270 litres

Measuring a Rectangular Water Tank, eg a slim line water tank

Slim line water tanks are a little more difficult to measure, but not too much. To work out the size exactly, you just need to take into account the flat middle section and then both rounded ends. Each end of the water tank is like a semi-circle. I will assume each end is the same as this is usually the case.

To measure you need:

h - height

d - width of flat middle section

a - width of water tank

b - distance from flat section to end of tank

volume is then:

2 x area of end pieces plus area of middle section

2 x p x (a/2) x (b) x h + a x d x h where p is pie = 3.14159

so for a 1.8 m high tank, with a flat section that is 2 m long, is 800 mm wide and b is 500 mm.

2 x 3.14159 x (0.8 ÷ 2) x 0.5 x 1.8 + 1.8 x 2 x 0.8

2.26 m3 + 3.4 m3 = 5.66 m3

This means the volume of water that can be held is 5660 litres.