Sump crock and pump

The Sump Pump

The sump crock collects water though a drainage system around the perimeter for the foundation The sump pump removes the water from the sump crock. The system is designed to help keep the basement dry. There are two components to every sump pump: the pump that discharges the water and the switch that activates the pump. Either the pump or the switch can require replacement. Water is removed form the sump by the pump that is attached to a discharge pipe. The discharge should be made of schedule 40 PVC pipe with a integrated check valve. The pipe should discharge to “daylight”- that is on to the ground or buried just below grade so that water can evaporate in to the air.


Sump pump diagram


There are two types of pumps: pedestal and submerged

The pedestal pump is often thought of as the older style with the pump motor placed on top a pedestal above the sump and out of the water.

Submerged pumps are designed to be placed in the bottom of the sump, below the water line.


There are three types of switches- pressure, float, and tethered float.

-The pressure switch operates when sufficient head pressure is exerted on a pressure sensitive switch and engaging the pump. This type of switch often does not operate properly in a shallow crock because sufficient head pressure cannot be exerted on the switch mechanism. These switches can also malfunction due to debris build up clogging the switch inlet. These work best in a deep sump crock.

-The standard float switch or side switch incorporates a float device that moves up as the water rises activating the switch. This switch works well in most applications.

-The tethered float switch uses a float device that contains a switch that when inverted, activating the pump. The sump crock needs to have a large enough circumference to allow the switch to float up without being obstructed by the crock side wall. These work best in large modern crocks.

All three types of switches have advantages and disadvantages. It is important the switch be best matched to the style of crock in use. The sump pump should be activated occasionally to check that that the pump operates properly. If the pump isn’t working, it may just be that the float is stuck or the pressure diaphragm inlet is dirty. Most switches can be replaced independently from the motor is there is a failure.

Backup Power

In situations where there is a lot of foundation drain activity or basement flooding is predictable, a backup power source should be considered. There are two types of backup systems, water activated and battery power back up pumps.

Battery powered units are the most common and reliable as long as the battery is properly conditioned and in good working order. Water powered back up pumps are used where there is a municipal water source.

The Discharge Pipe

The discharge pipe should have a one-way check installed and the pipe be secured to the foundation or basement wall. Often over looked, the location of the final discharge is important. It is important to keep the water at least 6-8 feet away from the structure. It wouldn’t make sense to allow that water to discharge right next to the house just to move right back down to the foundation and back into the sump.  Many installations discharge into a larger pipe that is buried under ground and allows the water to seep into the topsoil and to evaporate. Proper installation of the discharge pipe is important so that it does not become clogged with debris or freeze in the winter. Older homes may have the discharge into a dry well. Discharge water from the sump crock should not be directed into the sanitary sewer or the sanitary septic system.

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