Fountain rule

Allow us to introduce you to the fountain rule, it is called the "J.W rule"

The J.W rule states that the height of water emanating from a fountain / water feature jet should be no more than 50% of the diameter of the pool in which it sits.

This is because water will fall as far as it is high. 

So for example if you have a pool that is 4 M* across if you have a jet that is 4 M* high in this pool that means water can fall 2 M outside of the pool. Obviously over time this will empty the pool. this applies to ANY pool.

There are certain "Exceptions" such as if you have a large surface, such as a rock or wall where the water runs down its surface, or  wind controls to reduce jet height.

When designing a fountain this rule must be taken into consideration