The size of a sump pump depends on factors like the size of the basement or crawlspace, the water table level, and the potential volume of water entry. Sump pump capacity is measured in gallons per minute (GPM) or gallons per hour (GPH). A common recommendation is a pump with a capacity of at least 2,200 GPH for an average-sized home. However, consulting with a professional to assess specific conditions and requirements ensures the selection of an appropriately sized sump pump for effective water management.