pool and runoff coefficient

I consider a pool the same as a pond or lake. If the pool can contain the rainfall event with no discharge to the sanitary sewer, then the runoff coefficient is essentially zero. If, on the other hand, the rain that falls directly into the pool raises the water level sufficientl6y to overflow into the sanitary sewer, the runoff coefficient is 1.0. Many times the pool will have a bit of freeboard before the water level rises enough to overflow and this will allow you to capture the rainfall, and even make up for some evaporation that would otherwise be made up using potable water. Much depends on the overflow elevation compared to normal water elevation and the elevation at which makeup water is introduced into the pool to make up for evaporation..