A sump should be dug at the lowest elevation in the basement so that water will run down and collect in that spot.
A water-powered pump is not electric but works by using a valve hooked into the municipal water supply. As the pressurized municipal water flows through the main, suction is created and pulls the water out of the sump and into the discharge pipe. These pumps have a float-activated switch and are typically used as backup during a power outage. Models run about $400.
A battery-powered sump pump is also typically used as a backup. It fits next to the main sump pump and turns on during a power outage, main pump failure, or when the main pump can't keep up with the inflow of water. Models run from $150 to more than $1,000.
There are also backup sump pumps that are powered by generators. The generators must be rated for the sump pump's operational needs or wattage required to operate. These numbers are listed on the sump pump. When deciding on a sump pump, it is important to calculate the wattage required for startup of the pump and how many other appliances will require startup power from the generator at the same time.
For older homes that do not have a sump pit, there is a floor-sucker pump that removes water down to an eighth of an inch.
Sizing a Sump Pump Whatever the pump, it needs to be the correct unit for the job. For example, if a sump fills so fast that the pump is running a lot, the pump may be too small to do the work. Conversely, if flow into the sump is slow, there's no advantage to a larger pump.
There are two key considerations when choosing a sump pump: Capacity or waterflow; and lift required to discharge the water. Capacity can be determined by considering the area of drainage and depth to the groundwater or by measuring the amount and flow rate of water entering the basin during a heavy rain. Sandy soils have more gallons per minute entering the basin, meaning a larger system capacity, than do clay soils that hold water.
A pump is also judged by the amount of vertical lift required to take the water up through the discharge pipe until that pipe becomes horizontal outside. Sump pumps are rated by how high they can raise the water for discharge without losing flow. Charts or graphs explain the flow versus height-of-lift for each sump pump. Flow is usually shown as gallons per minute or gallons per hour. The height-of-lift is given in feet of vertical lift.
Maintaining the Sump System Problems do occur, so a sump pump needs occasional check-ups. The float can get hung up and need repositioning. The float may also fail to shut off the pump when the water level drops and need replacing. Debris can clog the pump's intake screen or valve and need to be cleared. The discharge pipe may be plugged or frozen. Batteries need to be replaced periodically. A pump that sits unused for a long time may seize up.
To check how a pump is working, remove the cover and slowly pour water into the sump until the float rises and starts the pump. When the pump is running, the water level should drop. Once it gets below the float, the float will trigger the pump to turn off. If that is not happening, it's time for a maintenance call.