In Texas, there are an estimated 150,000 abandoned water wells, and each one poses a threat to water safety, says Bruce Lesikar, Texas Cooperative Extension agricultural engineer. If the abandoned well is uncapped, a contaminant can easily enter and potentially pollute the underlying aquifer.

In some cases, landowners can close the well themselves. Landowners can generally plug both water wells with less than 100 feet of standing water, and large diameter, hand-dug wells, Dr. Lesikar says. But before any work is done, you need to check with your state or local water district for information on what paperwork must be filed.

To plug the well, the dimensions are taken, debris is removed, and the well is disinfected with bleach. Some of the outside casing is removed, and the well is properly filled. In Texas, the last step is completing the well-plugging report, which is critical to documenting the proper closure of the water well.

Wells can be filled using bentonite chips (an absorbent aluminum silicate clay), cement slurry, clay or caliche soil, says Dr. Lesikar. If well type or depth requires a professional to fill the well, or if the job is too much to handle, a licensed well driller and pump installer can legally fill wells according to code.

State laws vary on this matter, so contact your local water district or extension agent to find out how to go about plugging up abandoned wells.