Sump Pumps and Perimeter Drains: The Ultimate Guide

Date Published: October 5, 2023

Water and moisture are one of the biggest threats to the exterior of a house. So it is crucial to have a solid exterior defense system to protect your home. Of course, you need a suitable roof, a good foundation and siding, and sufficient grading. But even if a home is well equipped with all these features, water will often find its way down through the ground, trying to sneak through any imperfections in the foundation. That’s where a good perimeter drain and sump pump system can save the day!

During home inspections, we receive many questions about how sump pits and pumps work. We typically explain that sump pumps and drains are the last line of defense against water intrusion, while the proper watershed of a home and proper grading are what most homeowners should focus on. The less a sump pump gets used the better.

However, if you want to significantly reduce the potential for water damage to your home, then you better bet that you need a solid sump system! Let’s take a closer look at what it’s all about and why it’s so important.

What Are Sump Pumps and Perimeter Drains?

Simply put, sump pumps and perimeter drains are equipment meant to protect a home from water intrusion and pressure. Heavy rain, snowmelt and rising groundwater causes water to work its way into the soil and toward the foundation of the home.

If unhindered, the water can then seep in through into the basement and crawlspace and wreak havoc. Additionally, residual water build-up can create hydrostatic pressure against the foundation, and cause potential structural damage.

The sump pump and perimeter drain are a great duo that serve as the last line of defense against these types of water-related issues. They are generally found in homes with basements and crawlspaces. However, these systems weren’t required by building code until the middle of the last decade, and so some older homes won’t have systems installed.

However, in this article, we will focus on the most common installation method you will see on most modern builds.

sump pump diagram

Image sourced from: https://www.fema.gov

How Does It All Work?

Perimeter Drains

A perimeter drain  (sometimes known as a footing drain or a weeping tile) is a long, flexible plastic tube that extends around the entire perimeter of the home. This pipe is perforated with thousands of small holes, often fitted into a permeable, mesh sock. The sock allows water to flow into the pipe, but helps to prevent soil or debris from entering the pipe.

Builders will dig a shallow trench in which to lay the piping. Once the pipe is laid, it will be covered first with larger gravel, followed by finer gravel, then finally soil. This layering of descending sizes of gravel, helps to filter out chunks of debris as water seeps toward the pipe.

Perimeter drain covered in gravel.

Vertical sections of piping can also be installed at each window well, which then tie into the perimeter drain (as shown below). This configuration helps provide ventilation for the piping system to promote water flow. Furthermore, these sections of piping also serve as drains for the window wells when there is heavy rain fall or snowmelt.

Window well drain.

The trench should have a slight grade leading toward a sump pit. The sump pit is hole dug below the surface of the basement or crawlspace floor. A plastic tank is installed in the pit, and this is where the perimeter piping drains. This is where you will find the sump pump.

Perimeter drain heading to sump pump

Perimeter drain tying into a sump pit.

Sump pit before sump pump has been installed

Sump pit.

Sump Pumps

The sump pump is a motorized device that is designed to pump water out of the the sump tank once it reaches an established threshold. There are two major types of sump pumps – float and pressure.

As illustrated in the picture below, the float style pump has a float that rises with the water level. Once the water pushes the float up to a certain height, a switch is activated. When the switch turns on, the pump will send the water up through a discharge pipe and out of the house. This process repeats each time the water reaches that same height.

A pressure pump works similarly in that it pumps water once a certain threshold is reached. The difference is that it has a water pressure gauge. Once the gauge is fully submerged and reaches a certain pressure, then the pump kicks on to discharge water.

Sump pump diagram

Inspecting Sump Pumps

Here in Colorado, we may get lots of sunny days, but we also get plenty of snow and rain. That’s why having a properly operating sump system is such an important aspect of a home. This not only mitigates potential water intrusion and foundational damage, but it also helps to reduce soil erosion around the foundation. Using this method is bound to save you money one way or another!

Also, Colorado is well known for its terrible soil. Clay-heavy soils can expand with moisture, which is a big cause of structural issues. The better you can mitigate and move water away from your foundation, the better chance you have of keeping your foundation in great condition.

When conducting home inspections, we always make sure to inspect the sump pit when present. If the pump is a float style, we can test it by reaching in and pulling the float up to see if the motor kicks on. However, we are unable to manually test pressure-based pumps. Regardless of the pump type, our inspectors will always make sure the water level is at or below the drain inlet as an indication that the pump is working properly. And while this can be a limited inspection, it is a great indicator of a pump working during the inspection.

At Scott Home Inspection, we proudly offer complete performance assessments of CO homes – from the roof to the basement, and everything in between (including sump pumps). If you are based in the Colorado Front Range, and in need of inspection services, we would love to be of service! Visit us online to learn more, or book your services today!

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About the Author: Chris Kimmel

Chris Kimmel worked as an Associate Home Inspector for two years, handling numerous services including sewer scope inspections, pest inspections, mold air sample testing, radon testing, and water quality testing. Chris now works with Scott Home Inspection as a Content Writing Specialist.

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