Originally Posted by **piupiu** Hi, **I would like to know how to calculate the force on side of a water storage tank.**. |

OK ..fair enough .. lets take the side 3m by 5m ....=15 square meters

So you want to find the force that is pushing on that whole wall

We saw in my previous post the pressure under 3 m of water depth is 0.2904 Atmospheric pressure , or 29.4 KPa (KN/m squared)...

But at the top of the tank the pressure is zero , and as you move down the pressure increase linearly to the max 29.4 at 3 m

So the

**average pressure** on the wall is 29.4/2 = 14.7 KN/m squared

And the area of the wall is 15 msq ...

So force is ...15 x 14.7 = 220.5 KN or 22.05 tonnes weight

**The force pushing this wall out is equivalent to the weight of 22 tonnes in earth gravity ** ...I kid you not ...that is correct!

**And the force pushing downwards on the bottom of the tank is 60 tonnes**
If the tank is resting on a flat solid surface this is no problem , the surface pushes back supporting the bottom ....

But if the tank was supported by it's edges as it might be if on a tower , the the bottom of the tank had better be strong enough to hold the weight of 60 cars without buckling! and this is a relatively small 4 by 5 meter bottom.