How Does a Sump Pump Work?

• By Andrew Fox
•

Before we talk about sump pumps we need to describe what it is supposed to do.  The purpose of a sump pump is to remove storm water or flood water from your home.   A sump is a low space that collects liquids.  It is also referred to as an infiltration basin used to manage surface runoff water.   The most common location of all sumps is the lowest point in a basement or crawl space, into which flows water that seeps or is piped in from the outside.  If water is regularly flowing into this sump, a pump is added to move water outside and away from the foundation.

Perimeter Drainage

In areas where homes are more subject to heavy amounts of hydration or in jurisdictions where required, a perimeter drain tile is added underground around the foundation.  This drain tile is directed into the sump pit or crock.  The drain tile is, in most cases, perforated and will allow excess water at the foundation to enter the system before it has the opportunity to seep in through the foundation.

What is a Sump Pit?

The sump pit, also known as a sump crock, is a basin at the lowest part of the basement or crawl space that the perimeter tiles terminate into.  This basin is placed deep enough to allow the drainage pipe to fully evacuate all of the collected water and to not allow water to hold in the pipes.  Allowing water to hold in the pipes will keep unnecessary moisture against the foundation and provide for a damp feeling space and a potential for mold growth.  These drain pipes are extended into the pit far enough to create a well-sealed union.  If the drainage pipe does not extend into the pit, there will be a high likelihood or opportunity to have the extra hydration erode under the foundation or not be fully collected.

What is a Sump Pump?

A pump is placed in the pit.  So, what types of sump pumps are there? There are two basic types of sump pumps; submersible and pedestal.  Let’s take a quick look at the difference between these sump pumps:

  • What is a Submersible Sump Pump?
    • A submersible pump is a fully contained electric pump that is placed at the bottom of the sump it
  • What is a Pedestal Sump Pump?
    • A pedestal pump has the pump, or impeller, placed at the bottom of the pit while the motor is above the pit, in the open air

Both pumps should activate and operate automatically, doing so without fail and without human contact.  If the system has to be manually operated, there is a high risk for failure.  In order to operate automatically there has to be some form of switch. The two most common sump pump switches are float activated and pressure activated.  The float is a very common method.  Within the pit, there is a floating device this has a tilt sensor.  If the float rises to a pre-set level, it will activate the pump and allow it to remove all of the water from the pit.  If it is a pressure system, the level of water above the sensor causes the switch to activate the pump.

Regardless of the type of pump and sensor being used, there should always be a back-flow or check valve installed in the discharge pipe above the unit.  This prevents any discharge water from dropping back into the pump at the conclusion of the pumping cycle.

Common Sump Pump Issues

A sump pump can fail.  The most common life span of a sump pump is seven years.  The drain tiles can become clogged with debris or root intrusion.  You also want to monitor the float activation, as water in the pit should never be high enough to flow back into the drain tiles. However, the most common issue with a sump pump is the easiest to predict — without power the pump cannot operate.  To fully protect your foundation, and your home, consider installing some form of alternative power to operate your sump pump. Also, be sure to check out our seasonal home maintenance checklist for tips on other home care things to monitor.