AP NEWS

What is the water table, and how does it affect homes?

March 31, 2019

The groundwater table plays a role in home construction, foundation stability and home comfort. Because the groundwater table is so significant, it behooves homeowners to understand how it works.

National Geographic defines a water table as the boundary between water-saturated ground and unsaturated ground. Well beneath the ground, at various depths depending on geography, topography and weather conditions, pockets of water, called aquifers, exist. The water table marks the boundary between that available water and the dry surface.

Ground water is impacted by precipitation, irrigation and ground cover. It also may be affected by land use and tides. The water table can fluctuate with the seasons and from year to year because it is affected by climatic variations, as well as how much water may be drawn from underground, advises Encyclopedia Britannica. The water table where one person lives may be several inches or feet below the surface of the ground and follow the topography of the land. For others, it may be much higher, even coming above the surface of the soil.

The water table as well as local soil conditions and drainage can impact homes and their foundations. If soil drains efficiently and there is a relatively low water table, it may not be problematic. However, if soil is dense and absorbent and the water table is high, the ground around a home may swell and become saturated. This can exert significant pressure against the foundation walls, states Rytech, a water damage and mold rehabilitation company.

In areas where a local water table rises near the surface, water can push against the underside of the foundation in a condition known as “hydrostatic pressure.” This may cause water to infiltrate through the bottom of the foundation — even permeating solid concrete over time. If hydrostatic pressure is severe, it could lift certain portions of the foundation out of the ground, but this is very unlikely. But it could cause shifting of foundation walls and structures like fencing and decks.

Even if ground water does not cause foundation cracking or shifting, it could lead to humidity issues, resulting in rust, bacteria and mold. Wood structures in a home may be compromised by a high level of humidity.

The home improvement resource Angie’s List says certain steps may need to be taken to protect against damage from a water table and abundant ground water. Basement and foundation waterproofing professionals can help homeowners develop a plan to mitigate water damage. This can include grading changes and the installation of drains and pumps to move water away from the house. Special paints and sealants also can protect the foundation.

Ground water can be a hindrance when it affects the home, but homeowners who learn about it can be in a position to confront any ground water issues.