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The Basics of Sump Pumps

Sump basics: Standard sump pumps are electric, powered by household current. There are two main types: submersible and pedestal. A submersible pump is completely concealed inside the tank. A pedestal model has a column that protrudes up through the tank’s cover; the motor is mounted on the column, above the floor level. Both types draw water in through a filter trap (this should be cleaned periodically). They pump water out through a discharge pipe and/or hose. As soon as an automatic pump empties the tank to a certain level, its motor turns off.

First decide between a pedestal and submersible pump. A submersible is out of sight and earshot, an important advantage if the basement is used as a primary living area. It’s also much safer if there are children in the house.

But pedestal pumps are less expensive and last longer. Because submersibles sit in water a good deal of the time, they have a life span of from 5 to 15 years. Pedestals, on the other hand, may continue to operate for as long as 25 or 30 years. (Because a pump’s life is closely related to the conditions and frequency of its use, most manufacturers offer limited 1-year warranties.) Pedestal pumps are also much easier to repair.

Switches: Automatic switches come in several types, including floats, diaphragms and mercury switches. It doesn’t really matter which type you choose, but be sure to choose one of them. By the precepts of Murphy’s Law, if you put in a pump with a manual control, you won’t be home to turn it on the next time your basement begins to flood. An automatic switch can protect the pump, too. Most pumps burn out if they run “dry” for too long. An automatic switch prevents this from happening.

Price: Price is directly connected to a unit’s strength. Almost without exception, the least expensive models are also the weakest. A sump pump is measured by horsepower—pumps range from 1/6 to 1/2 HP.

But more important is the number of gallons per minute (GPM) or gallons per hour (GPH) a pump will move. This capacity is a factor of both the pump’s efficiency and the “head” or “lift”—that is, the vertical distance from the bottom of the sump to the highest point of discharge. A pump may advertise “2400 GPH” but this may be measured at a 1-foot head. At a 5-foot head, that figure might drop to 2100 GPH and at 10-feet, 1800 GPH. Also note whether the pump is strong enough to pass small solids, such as leaves and twigs.

Materials: Materials that make up a pump also affect price. Look for parts and housings that won’t corrode—cast bronze, alloy, stainless steel and epoxy-coated cast iron housings are favorable; avoid sheet metal. Polypropylene and related plastics are used in all grades of pumps.

Pay attention to the power cord’s length, too. They come with 5-, 10-, 15-, 20- and 25-foot-long power cords. Extension cords shouldn’t be used with sump pumps.