Some degree of water loss is a normal part of owning a pool. Evaporation, splashing, and the natural movement of water during use all contribute to a gradual decline in water level that requires periodic topping off. What is not normal is a water level that drops consistently and quickly, or one that requires frequent refilling to maintain. When that pattern develops, a leak is the most likely explanation, and addressing it promptly is considerably less costly than allowing it to continue.