The author had earlier published formulas for evaporationfrom occupied and unoccupied indoor swimming pools.The formula for unoccupied pool was derived from the analogybetween heat and mass transfer during natural convection. Itwas shown to be in good agreement with all published test data.However, it was applicable only to positive density difference(i.e. when the density of room air was greater than that of airat the pool surface). It has now been extended to apply to negativedensity differences. It has also been extended to include thecase when air is forced over the surface of the pool to removeoff gases. Calculation method is also provided for varioustypes of occupied pools. Tabulations of calculated evaporationrates from unoccupied pools at typical design conditions havebeen provided.