Should There Be Water In My Sump Pump Pit?

Many people wonder if it is normal for a small amount of water to remain in the sump pump pit after the pump finishes its pumping cycle. This is a natural question for anyone who is not intimately familiar with how a sump pump operates. Whether or not water should be left in the sump pit after the pump shuts off can depend of a few different factors. 

How a Sump Pump Works

First, before you can determine if the water in the sump pit should be there, it is important to understand how a sump pump operates. As water runs downhill, a basement is the natural place for water to accumulate in any building that has a below-the-ground foundation. Unless preventive measures are taken to keep the water away from the foundation, most basements that set below grade will eventually get wet. However, there is a big difference between becoming “wet” and underwater. 

A properly installed sump pump will keep your basement from becoming flooded. A sump pump sits in a sump pit below the basement’s floor level. Some basements may have an in-floor drainage system that channels water into the pit for the sump pump to discharge, typically into the sewer line or an ancillary drain that leads to the building’s exterior. Because the sump pump sits below the level of the floor, it drains out any water that penetrates the foundation before the level of the water can rise to the level of the basement floor. 

Sump pumps are designed to automatically activate, via a switch connected to a float, when the water in the pit reaches a certain level. This float switch works exactly the same way as the float in your toilet, except in reverse. The float in your toilet tank drops as the water level does when the toilet is flushed, opening to allow water to refill the tank, and shuts off when the tank is full. However, a sump pump comes on as the water level rises and raises the float and then shuts off again when the pump has expelled enough water from the pit for the float to drop enough to turn off the sump pump, until the water raises the float again. Because of the way sump pumps are designed, this cycle typically allows a few inches of water to remain in the pit after the pump shuts off. 

Should Water be in the Sump Pump Pit?

It is perfectly normal for a few inches of water to remain in the sum pit during periods of heavy groundwater runoff, such as heavy rains or snow melt, after each pumping cycle ends. However, if there is water in the pit even during dry periods, when there has not been any recent groundwater runoff, you may have a broken or leaking pipe that is causing the pit to stay wet. 

Checking for Leaking Pipes

The easiest way to determine if the water in the pit is the result of a leaking or broken pipe is to shut off the main water supply to the building for a few hours and see if the water level in the pit rises. If the water continues to rise with the main water supply shut off, then the water in the pit is most likely the result of a naturally high water table. The residual water in the pit in this situation is normal, and there is nothing to worry about. However, if the water level in the pit stops rising, or recedes, with the main water supply shut off, then the water in the pit is most likely being caused by a water leak somewhere in the plumbing system. 

The first thing to check is the sump pump discharge hose and fittings, because if either are compromised the water the pump is trying to evacuate from the pit is simply running right back into the hole. Wait for the sump pit to fill up enough with water for the pump to activate and then carefully examine the length of the sump pump hose and the clamps at both ends of the hose, if present, for leaks.

If water is leaking from the hose it may be a simple matter of replacing the hose and or clamps, or perhaps just tightening up the offending clamp. However, if the sump pump hoses and clamps look good, you will probably need to call a plumber to find the source of water infiltration, or try to fix the sump pump yourself.

You then may want to try to reset the sump pump, unclog it, or try out any of the other troubleshooting tips on sump pumps that we have on our website. As a last resort, you can always replace it. We have various resources that you can consult on choosing the right sump pump for you.