Water Table and Negative Effect on the Basement
The water table is the water level below the ground surface that is completely saturated with water. The height of the water table is measured by the meter (m). Water table height can rise and fall according to the accumulation of the groundwater.
During the rain and snow melting season, groundwater can rise and reduce during the dry season. The water table negatively affects the below-ground constructions such as the basement. These 4 signs help you to identify the level of the water table, such as basement seepage, continuous water leaking, septic tank level rising, and stain marks on the basement walls.
The negative impacts of the water table on the basement are water seepage, water leaking, dampness on the walls, mold and mildew growth, reduced basement stability, foundation cracks forming, and rotting the wood foundation.
Building a French drain system can reduce the water table effect on the basement wall. If the water table is higher, you should build both exterior and interior French drain systems. For the shallow basement interior French drain is sufficient to minimize the water table effect. You should follow the proper step-by-step guide to build a French drain system when you do it DIY.
What is a Water Table?
The water table is the water level below the ground surface that is completely saturated with water. The boundary of the water table is between water-saturated soil (below the water table) and the unsaturated, or 'dry', soil above. The water table level can rise during the rainy season and go down in dry seasons. The ground water table is not flat; it has peaks and valleys. It varies with the landscape.
What is the Depth of the Water Table?
The depth of the water table is the distance from the ground level to water-saturated soil on the top of the water level boundary. The depth of the water table is measured by the meter (m). The groundwater table can vary depending on the area and the time of year.
Therefore, water table depth can vary with groundwater saturation. When the groundwater is saturated by water, the water table height is reduced, while desaturation of ground soil can increase the water table height.
What Happened to the Water Table During the Rain?
During the rainy season water table can rise. The water table rising can cause flooding in areas where the water table is naturally high. Due to the water table rising it tends to increase the water pressure in the soil profile. The increase in water pressure negatively affects the groundwater structures. Due to the pressure increments, water can seep through the groundwater structures such as foundations and basements.
What are the Signs of the Water Table in the Basement?
The water table is not increase all over the year. It rises when the water accumulates underground. The below signs will help you to understand the water table under the ground.
- Seepage on the basement walls: Continuous basement seepage can occur due to permanent water sources
- Stain marks on the basement walls: Stain marks on the basement wall up to a certain height can be a common sign of a water table. Stain marks can occur due to prolonged seepage.
- Continuous leaking and seepage: When you observe continuous water leaking and seeping the water during and after the rain or snow melting, it is one of the signs of an underground water table.
- Septic tanks level up: If the septic tank level is rising up rather than its regular level, it will be a sign of the water table underground.
What are the Effects of the Water Table on the Basement?
The water table affects the basement negatively. Because the rising water table increases the pore water pressure and increases the seepage rate. Below are the most severe water table problems on the basement.
9 negative effects of water table on the basement
- Water can seep through the pores on the concrete basement: Higher water pressure tends to pressure the water through pores on the basement walls.
- Water can leak through the cracks and joints in the basement: A higher water table makes higher water pressure. Hence, it tends to weaken the cracks and joints in the basement.
- Dampness on the basement walls: Basement walls can dampen due to a higher water table.
- Mildew and mold growth in the basement - Due to the continuous seepage and higher humidity, mold and mildew growth can occur in the basement.
- Higher seepage and leakage can flood the basement: High seepage and leakage can accumulate the water and then pump it out. This can cause water to stand in the basement.
- Reduce the basement stability: A higher water table has a higher water pressure. It can affect the soil stability. As a result of this, foundation stability will be reduced.
- Build foundation crack: Due to reducing the soil stability, foundation cracks can occur.
- Basement erosion: The basement can erode due to heavy water pressure in the basement wall over time. This can occur when the water flows inside the basement wall.
- Wood foundation rotting: When the foundation is made of wood, it can be rotting due to prolonged open to water. It will reduce the structural strength of the building.
How Do You Lower the Water Table Around the Basement?
You can reduce the water table around the basement by building an exterior drainage system. This drainage system is called a French drain. The French drain is an exterior drainage system that is built around the outside perimeter of the basement in order to accumulate excess saturated water close to the basement wall. The French drain is essential for the higher water table areas and higher grading lands.
Can You Waterproof the Basement With a Higher Water Table?
Yes, you can waterproof the basement with a higher water table. You should build an interior French drain system to waterproof the higher water table basement. You should follow these steps. You have to drill through the basement wall to leak the outside water properly.
Then, build a drain to receive the leaked water. This should be done along the perimeter of the basement and the drain should be pointed to the one hole (sump hole) below the basement level in the basement. Then, you can place a submersible pump to remove the accumulated water from the sump hole.