Some may not know this but your pool water is actually being refreshed every day! Every 24 hours, by running your pump for eight hours, water is pushed through your pool filter. If you find yourself wanting to drain and refill your pool, it is best you do so every 5-7 years (in mild weather conditions).
Replacing swimming pool water in hot weather may cause the pool surface to be affected by strong sunlight. However, removing the water after heavy rains or storms may put extra pressure on the pool bottom.