FAQ: "What is a Well Log?"

Question

Where can I obtain my well log and what information does it contain?

Answer

Depending on your location, your state or county health department, Department of Natural Resources, or some other similar agency may house well logs that you can access or request a log from. If you know who drilled your well, it might be a good first step to contact them and ask for your log. They should be able to provide a copy to you. If not, search online for ‘“your state” well construction code’ and the relevant state agency should come up. Call them, and find out what agency houses well logs, if any, and that will get you on your way.

You will need to know the legal description of the well location, and additional information that will be helpful include the drilling company that installed the well, the depth, the date drilled, and the original owner, if not you. In some states, only the owner can request the log, but in others it is public information. ;There are a number of states, including Illinois, that have websites with interactive maps that allow you to zoom into your location and see what logs are available, as well as other information in some cases, like water quality information.

The problem many well owners find is that there log is not on file with these agencies. The laws have changed over time, but 40+ years ago, most states did not require a driller to get a permit or file a log, so if you have an older well, the drilling company might be your only hope. In these cases, if there is information that you really need, like pump or well depth, it might be that you need a contractor to come out and determine this for you.

As far as what is on a well log, this also varies by state and jurisdiction. Below is a well log from Illinois, and this is what we can say about this well based solely on the log. This is a 318 ft deep well, constructed with 314 ft of PVC and a 4’ stainless steel screen at the bottom. The water bearing unit is course gray sand from 307-318 feet below land surface. Sim’s Drilling Company drilled the well for Tom Parrett, the land owner. It shows the legal description of the location as well as the location in decimal degrees. The static water level is 140 ft below land surface, meaning there is about 180 feet of water in the well. They installed a 18 gpm submersible pump at 200 ft, meaning there is about 60 feet of water over the pump. It’s for domestic (home) use, the well was completed on 8-3-06, and the pump was installed on 9-6-06. They grouted the annulus from 5 feet below land surface to 148 feet below land surface as well.


If you are able to retrieve your well log, hopefully it has at least this information. It really does differ by jurisdiction.