Groundwater In Your Basement Isn’t Good. Here's What You Need to Know

Ginny Bartolone
Written by Ginny Bartolone
Updated April 25, 2022
grey house with porch and backyard
Photo: Iriana Shiyan / Adobe Stock

Highlights

  • Groundwater changes play a large role in the integrity of your basement and foundation.

  • When paired with poor drainage or waterproofing, groundwater can lead to issues.

  • Mold, bacteria, pests, and rot are common problems caused by leaking groundwater.

  • Proper basement waterproofing stands up against hydrostatic pressure.

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The foundation of your home is in a constant dance with nature, and groundwater plays a large role in the tango. When hydrostatic pressure—in this case, water pressure—becomes too great for the walls, floors, or basement footing, you could end up with a costly headache and a long day with a shop vac. Let's walk through the obvious and more subtle issues caused by groundwater in your basement.

What You Need to Know About Groundwater

Dig a hole in your backyard, and after a bit of elbow grease, the hole will eventually fill with water. How long it takes to reach water depends on your land, rain amounts, and soil density. This represents the water table—or the area where groundwater saturates into the earth.

The water table around your home will play a significant role in how much pressure your basement or crawl space handles daily. Groundwater can change or differ depending on a few main factors, including:

  • Recent rainfall or snowmelt

  • Clay concentration in your soil

  • Proximity to major bodies of water

  • The slope of your lawn and proximity to hills

  • Direction of your gutter drainage pipes

Keep in mind that soil is just as important as the water itself in this equation. As the soil shifts, expands, and shrinks with the rise and fall of groundwater, it will also place greater pressure against the side of your basement.

How Groundwater Enters Your Basement

When you have a properly waterproofed basement, you shouldn't have to worry about the changes in groundwater. The right combination of interior and exterior waterproofing and drainage will keep groundwater outside where it belongs. But the most common causes of basement flooding from groundwater often stem from these systems wearing down over time.

Basement Cracks

Miniscule cracks in your basement floors and walls are the most common way groundwater enters your basement. A quick change in hydrostatic pressure from, say, a storm or misdirected rainwaters, can simply press too hard on the structure, causing small amounts of water to enter your basement.

Water Wicking

Also known as capillary action, water from below the footing of a foundation can move through the stones of your basement and leave your walls and floors wet. The process often indicates too much hydrostatic pressure underneath your home and requires better drainage.

Improper Basement Drainage

Homes built on high water tables should include additional defenses against groundwater in basements and moisture problems. There are many different types of basement waterproofing methods, from epoxy sealants to French drains. Sump pumps are also common in flood-prone regions. If these tools fail to work in tandem, you end up with a floor of puddles or worse.

Condensation

While condensation technically comes from the air, not groundwater, it's important to include it in our list. Condensation on basement floors occurs when cold air hits the warm surface on your basement walls and floors.

Common Basement Problems Caused by Groundwater

Let's say that the groundwater pressure rises higher than your basement can handle and water makes an appearance inside your basement. Here are the most common categories of groundwater damage and their related issues to keep in mind.

High Humidity

Let's start with the smallest amount of water—high humidity from the occasional breakthrough of groundwater. Perhaps you only see a few puddles on the floor when you have a big storm, and your sump pump kicks in with any larger issues. High humidity in your basement can lead to:

  • Oxidation of metal appliances such as your boiler, water heater, or washer and dryer

  • Wood rot in structural beams and furniture

  • Buildup of mold and bacteria that can lead to allergy issues or poor air quality

  • Attraction of pests to moist areas

Damage to Your Foundation

Areas prone to constantly changing groundwater can break down the integrity of your foundation over time. If the soil quickly expands or contracts, the push and pull can lead to cracks in your foundation walls, floors, and even the footings beneath. Larger shifts in the earth can cause soil areas beneath your home to move, leading to foundation shrinking or upheaval. Both can lead to uneven or bowing floors and structural issues throughout your entire home.

Flooding

In the worst-case scenario, groundwater will overwhelm your basement's waterproofing methods and lead to a flood. Flood damage can range from the relatively small-yet-intrusive issues we listed above to major damage to your appliances and personal items. 

If you have to clean a flooded basement, the process can be lengthy, so it's important to immediately call a local basement professional. The team will wait to find the water source and create a plan to add drainage and proper sealants for your basement.

Preventing Groundwater in Your Basement

Installation of waterproofing membrane to insulate exterior basement
Photo: Lex20/ iStock / Getty Images

By this point, it should be pretty obvious groundwater can have a pretty significant effect on your basement and foundation. The waterproofing process is two-fold for this reason. Experts install exterior drainage to control major changes in groundwater and interior waterproofing to control the remaining pressures of groundwater. 

Common methods include:

  • Sump and pump installation

  • Waterproofing paint and sealants

  • Cove sealing

  • Dehumidifiers

  • Epoxy injections

  • French drains

  • Weeping tiles

  • Yard grading

The cost of basement waterproofing varies anywhere from about $4,900 to $10,500, but the investment is integral to the longevity of your home. If you're concerned about the effects of groundwater on your basement, do not hesitate to reach out to local waterproofing specialists for a consultation.

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