Midwest homeowner has groundwater under basement floor and needs help
I received an e-mail from a reader in the midwest of the United States. This homeowner has groundwater leaking along the basement footing and under his basement floor. He asked for my opinion with respect to his perceived need for a sump pump installed to pump out the groundwater.
The larger question that needs to be asked however to solve this groundwater problem does not exist within the premise that groundwater is entering his basement from below grade, but why and how it is getting below grade and saturating his basement floor.
I told him that he should ask himself a basic question. Does the groundwater come in throughout the year, on a steady flow basis, or does the flow pick up during the rains? Most groundwater problems like his are caused by saturation and hydrostatic pressure that comes from not having hand excavated french drains on the surface levels between 8″-18″ deep to collect the rainwater, as it is raining, preventing saturation and hydrostatic pressure.
The fact that, once the side of the foundation is saturated, 8 feet deep probably, the foundation wall continues to leak and the groundwater floods below grade and under the floor, does not form evidence in my mind that his groundwater problem is caused by underground springs or rivers.
First off, most homes are not so old that they did not go through some sort of subdivision or county approval for siting, which pretty much tells you that the property is not in the flood plane or contains sufficient year round underground water, or it would not have been approved for construction by the city or county in the first place.
The more likely scenario is that the groundwater problem is caused by not having a compacted and sloped splash block of dirt and clay at the exterior foundation wall, and no hand excavated french drains.
It is very common also for rain drain dishcharges and gutters to contribute to this problem. Once the foundation is wet to that degree, around 8 feet deep in most cases, and the fact that no hand excavated french drain system exists to cut off the addition of groundwater at the surface levels that creates the weight and hydrostatic pressure, it only makes sense that groundwater would be there to a degree forever, just waiting for the next hard rains to get worse and continue the whole process at a greater pace again. Pumping is not the solution. It is a bandaid.
It is a self fulfilling prophecy that a sump pump is needed, in the homeowners mind, because you are always pumping groundwater if you do nothing to stop adding to the weight of the already existing saturated soil and previous groundwater in the soil by not having hand excavated french drains installed.
When you are confronted by this scenario, remember that it is super common, and if you want to be the tail wagging the dog, just keep pumping. If your goal is to solve the groundwater problem, stop adding groundwater weight to the side of your foundation with time tested methods of groundwater removal. Install hand excavated french drains. Very few homes are actually on top of underground rivers or year round groundwater flows. Cut the groundwater off on the surface and give yourself 6 months to start seeing real results. Pump if you want in between, but don’t forget to stop that saturation, and eventually shut off those sump pumps forever. Almost 100% of the time homeowners who argue for the necessity of pumping do not have a good compacted grade at the foundation, no hand excavated french drains properly engineered, installed, and placed; and probably other factors as well on the outside of the home contributing to the flow of the rainwater to the side of the foundation wall on the outside of the home. Sometimes it is the ground under decks that slope to the foundation. Sometimes concrete floated to slope towards the home is the problem. Sometimes trees planted right on the foundation with roots that have made in roads are the problem. Any below grade collection swales or trapped areas behind berms that can trap rainwater between the berm and the foundation wall, usually planted for curb appeal, can be a huge smoking gun for this kind of groundwater problem below grade.
Read this website for information on these and other common home drainage problem causes.