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Why are Sump Pump Check Valves Important?

By Braedlyn McEwen

A sump pump is designed to collect and eliminate any water that can accumulate beneath a basement floor before the water can enter the basement. The sump pump is there to help protect your basement from getting flooded and a check valve helps the sump pump do it's job.

In this blog, we will explore the job of a sump pump check valve and the importance of installing one to eliminate sump pump short cycles, ultimately causing you to have a high electricity bill. Let's take a look.

What is a Sump Pump Check Valve?BSC-150-150B

A Sump Pump check valve is a flapper style, one way valve that gets installed in the discharge pipe of the sump pump. The flapper opens by the force of the water when the pump starts up. The valve flapper closes when the force of gravity pushes down once the pump has shut off. Some valves with a flat seat will make a clunking noise caused by water hammer when the flapper fully closes. The impact of the valve hitting the seat is the water hammer.

Why Install a Sump Pump Check Valve?

Pumping Efficiency

Once the pump starts to run, the water is forced out through the valve. When the pump shuts off, gravity wants the water that is in the discharge pipe to fall back into the pit. The check valve is there to prevent that from happening. The check valve prevents the pump from having to re-pump that water out which could result in short cycling. Eliminating short cycling will save on electricity costs in the long run.

Pump Protection

Short cycling causes the pump motor to run hotter. Heat is the enemy of electric motors because it can shorten the life of a pump drastically. By installing a check valve, you will reduce the risk of short cycling which will eventually extend the life of the sump pump.


The most suitable location for a sump pump check valve is close to the floor level to minimize the volume of water that drains back at the end of each pumping cycle and it is a convenient location for easy servicing or replacement of the valve. The check valve may be installed down inside the sump pit but installation and servicing are not as convenient making regular inspections extremely difficult.

Improper Installation or Not Installing one at all

Not having a sump pump check valve installed causes the water in the discharge pipe to empty back into the sump pump pit. This makes the water level in the sump pit rise and a high water level can cause the pump to run more often, increasing your energy costs.

If the check valve is installed in the incorrect spot such as too high up on the discharge pipe, the pump will empty the pit during the run cycle but when it shuts off, the water below the check valve will drain back into the basin causing the water level to rise very quickly. When that happens, it will trigger the float switch to start the pump again right away, eventually wearing out your pump too early.

ABS Sump Pump Check Valve

BSC-150This style of sump pump check valve has a 15° seat that reduces any noise caused by water hammer. It is created with a one piece flapper which ensures a positive seal. This style of check valve is a very universal sump pump check valve. It can be installed in multiple different ways:

  • With a 1-1/4" polyethylene pipe by clamping the pipe over the barbed end of the valve.
  • With a 1-1/2" Sch 40 PVC pipe by gluing a coupling directly to the valve right after the barb part of the check valve.
  • With 1-1/4" corrugated hose by clamping the hose over the barbed section of the check valve.
  • With 1-14" Sch 40 PVC pipe with the use of any 1-1/2" x 1-1/4" reducing bushing and 1-1/2" deep coupling.

Air Release Hole

FirstAn air release hole is also referred to as a weep hole or air vent. This hole is typically drilled in the discharge pipe approximately 5" above the pump discharge connection and below the check valve by the installer. The purpose of the air release hole is to provide a passage way to allow the air to exit that normally getsSecond trapped in the sump pump housing, preventing the pump from removing water from the pit.

Any check valves with a MPT (Male Pipe Thread) connection that are designed to thread directly to the sump pump discharge housing must have the air release hole drilled into the check valve body directly above the MPT connection and below the flapper. Having an air release valve with the moulded-in hole eliminates the time and expense of drilling at the time of installation.


Installing a sump pump check valve is critical, but it is also extremely important to ensure it is being properly installed in the correct location. Be sure to keep in mind pump efficiency, pump protection and location when you go to install a sump pump check valve. Proper installation the first time will save you time and money.

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Tags: Sump Pump Check Valves, Sump and Sewage