Sump pumps are a flood prevention device. They remove groundwater when the levels rise to prevent a flooding situation within the home. A sump pit, otherwise know as a basin,  is installed in the lowest area of the home and holds the pump which can detect when the water levels are increasing. This basin collects water and when the level becomes too high, it will pump the water out and away from the home through a discharge line. Sump pumps are normally wired but many also have a battery backup so that when the power is out, they can still operate. 

Sump pumps are strongly recommended if you live in an area that experiences flooding or if your basement is built under the water table. They are a very effective and efficient tool against basement flooding that can save you thousands of dollars in water damage.