Water Filtration Periods

Periods Required

The Effect of the Ambient Temperature

The safe periods of time that a filtration system on a UK swimming pool should be run for is dependent on the water temperature as shown in the following table.


Water Temperature
Daily hours that pump should be run
0 to 10 degrees C None
10 to 15 degrees C

2 hour when the pool can be polluted (no cover) and 1 hour otherwise

15 to 20 degrees C Whole pool volume / flow rate
> 20 degrees C Whole pool volume / flow rate x 1.5 + 1 hour for every extra degree C
> 25 degrees C Whole pool volume / flow rate x 2 with a minimum of 12 hours

Influence of Bathers

To calculate the influence of bathers using the pool on the required filtration periods just multiply the number of bathers x 2 and divide by the flow rate.

So for instance 6 bathers in a pool with a flow rate of 12 m3 per hour will require an extra 2 x 6 / 12 = 1 hour of filtration.

Number of Bathers allowed

The above rule allows the number of bathers that can use a swimming pool to be calculated

i.e. Number of allowable bathers = Design Flow Rate / 2