Where should my new well be located?

Well water availability is obviously the most important factor in deciding where to locate your well and will dictate what types of well you might have. There are other considerations that help ensure your water stays safe to drink and your well can be maintained and repaired. For example, if your well is buried or in a building, proximity to potential sources of contamination can be a concern, or you might not be able to repair your well or pump easily.

Your well should be away from buildings, wires, trees, and anything else that would prevent a drilling contractor from being able to access the well with a drill rig or truck. This ensures there is ample room for repairing a well, pulling a pump, or even deepening an existing well. Other important factors to consider are sources of contamination. Wells should be located as far as possible from features that could contaminate the well if they spilled, malfunctioned, or started to leak.

This figure shows setback requirements for constructing a new well in Minnesota. Setbacks are legally required minimum distances. This figure doesn't mean that all swimming pools should be located exactly 20 feet from wells — Instead, it's explaining that no swimming pool should be closer than 20 feet (and further is better). Though the specific regulations vary from state to state, these images demonstrate many of the factors a well owner needs to consider when locating their well. It's a good starting point for asking questions like: where's my septic system in relation to my well, where is my neighbor's septic system, and is groundwater flowing from the septic system toward my well?

Groundwater flow direction isn't always easy to determine. If you have a shallow aquifer, the flow direction is most likely toward a point of discharge (like a stream or river), so looking at the landscape might give you some idea of groundwater flow direction locally. But if there are other active wells nearby, pumping can draw ground water toward those wells, changing the flow direction.

For deeper aquifers, the flow direction is even more difficult to determine unless you know where the recharge and discharge areas are. If your shallow well is down gradient from your septic system, it means that the groundwater is flowing from the septic system towards your well. It could be a source of contamination. On the other hand, if your well is getting water from a deeper aquifer far below and not connected to the shallow water table, then a properly constructed well probably won't get contaminated from shallow sources no matter the flow direction. If you're concerned about groundwater flow direction, it's worth the effort to contact your state agency that maps aquifers and monitors well levels to request information on your aquifer. It might be that there was no other choice where to drill your well.

At the Illinois State Water Survey, we have seen wells over one-quarter mile from the house because there is no aquifer closer to the home. Geology can change dramatically over a very small distance, and with those changes there can be differences in what water supply is available. If you're in a subdivision with only a one-third acre lot, for example, there isn't much location to choose from. In these cases, what your neighbors are doing may also influence your well. If there are other wells in the area, are they pumping? If they're abandoned, are they properly sealed? Nearby wells are a potential route of contamination. If not properly constructed (and if they are in use), they can impact the direction of groundwater flow.

The Private Well Class is a collaboration between the Rural Community Assistance Partnership and the University of Illinois. Through the Illinois State Water Survey and the Illinois Water Resource Center, and funded by the United States Environmental Protection Agency. The views expressed here solely from the class authors and not endorsed or reviewed by US EPA. For more information on private wells, sign up for our free 10-week email course at PrivateWellClass.org.