A sump pump is a pump used to remove water that has accumulated in a water-collecting sump basin, and is usually found in the crawl spaces and basements of homes. The water may enter via the perimeter drains of a basement waterproofing system, funneling into the basin or because of rain or natural ground water, if the basement is below the water table level.
Sump pumps are used where basement flooding happens regularly and to solve dampness where the water table is above the foundation of a home. Sump pumps send water away from a house to any place where it is no longer problematic, such as a municipal storm drain or a dry well.
Usually hardwired into a home's electrical system, sump pumps may have a battery backup.
There are generally two types of sump pumps—pedestal and submersible. In the case of the pedestal pump, the motor is mounted above the sump—where it is more easily serviced, but is also more conspicuous. The pump impeller is driven by a long, vertical extension shaft and the impeller is in a scroll housing in the base of the pump. The submersible pump, on the other hand, is entirely mounted inside the sump, and is specially sealed to prevent electrical short circuits. There is debate about which variety of sump pump is better. Pedestal sump pumps usually last longer (25 to 30 years) if they are installed properly and kept free of debris. They are less expensive and easier to remove. Submersible pumps will only last 5 to 15 years. They are more expensive to purchase but can take up debris without clogging.