Sump pumps are great tools for people who live in areas where there is frequent flooding, either because of a high water table or a high occurrence of storms. This certainly includes much of the Mid-Atlantic, as many homes along the coast, especially during hurricane season, are prone to basement flooding and power outages.
A lot of properties already have sump pumps in their basement that essentially flush water right out through the lowest point in the floor. However, in most cases, these pumps are either powered by the home's electricity or a battery. In the event of a power outage, an electric sump pump is essentially useless and may be insufficient in getting standing water out of your house during large and damaging rain storms. In addition, if you don't regularly check to make sure that your battery-powered sump pump is functioning, you could unexpectedly find your basement filled with water after nasty weather.
To prevent these disasters, many homeowners look into installing a water-powered sump pump to do the work in the event that your electric or battery-powered pump fails when you most need it.
These pumps are configured to turn on automatically only in the event of a primary sump pump failure. The water-powered pump is hooked up to the city or town supply and essentially forces liquid through a constrictor, then an ejector, which causes a decrease in water pressure. This pressure variance causes the water at the pump level to be sucked out of your basement and mix with the city's water supply, exiting through a discharge line.
An experienced Washington DC plumber like John C. Flood can help you evaluate what precautions you should take in protecting your home from damaging floods.