Insect Note Logo with NCSU Brand and insect note mast Cooperative Extrension logoResidential,Structural
    & Community Pests
Department of Entomology
Insect Notes
Insect Note - ENT/rsc-22

Termite treatments must always be done in a manner that avoids damaging or contaminating water sources. Wells, cisterns and foundation drains can pose a challenge to termite treatments. Although these situations are difficult, there are options for protecting your home with some type of termite treatment.

Wells and Cisterns  
Most termiticide labels and some local building codes prohibit or limit soil treatments when a well or cistern is located under or within a certain distance of a house. This restriction is intended to prevent accidental contamination of your water supply and it applies even if the well is not in use. A liquid treatment may be possible if the well/cistern is located outside, although there may be restrictions or special instructions based on the distance of the well from the foundation (usually greater than 5 feet from the foundation). You can ask the pest control company to provide a copy of the pesticide label so you know how the treatment must to be done.
A house with a well within or near the
foundation may require special treatment.
Options for liquid treatments on houses with a well inside or near the foundation:
  • Most termiticide labels permit "treated backfill technique". This tedious and time-consuming procedure involves removing the soil along both sides the foundation wall near the well. The excavated soil is placed into a wheelbarrow or on a plastic tarp, then treated with termiticide, and then filled back into the trench along the foundation.

  • A well can be legally "abandoned" and you can drill another well elsewhere on the property. Abandoning a well does not mean that you simply stop using the well. There is still concern that the well and groundwater could be contaminated accidentally during a termite treatment. You can obtain a copy of the specifications for "well abandonment" through the regional offices of the NC Dept. of Environment and Natural Resources.

Subsurface (Foundation) Drains

Subsurface or foundation drains (sometimes called "French" drains) are used to prevent or correct moisture problems under and around homes. Many new homes in our area have drains installed during construction when the soil beneath the drain or backfilled on top of it can be treated in a way that avoids contaminating the drainage system.

Problems can arise when drains are installed on an existing home. Digging or removing the soil along your foundation also removes any chemical termite barrier around your home. Most termite protection contracts stipulate that removing or disturbing the soil along the foundation will void your termite protection guarantee. If you are planning to install a drain system around your home, then call your pest control company before you start the project.

Foundation drain being installed on new home.
Foundation drains may go unnoticed during a termite inspection. If a pest control company is going to treat your house for termites, make sure that they know about the drain before any work is started. This will help prevent accidental runoff of the termiticide into your yard, storm sewer, a pond or wherever your drain line empties.
Options for liquid treatments on houses with foundation drains
  • Prior to treatment, the applicators must take precautions to limit the risk of applying the termiticide into subsurface drains that could empty into any bodies of water. They must evaluate whether the application to the top of the foundation footer might contaminate the subsurface drain.

  • When appropriate (e.g., on the side of the structure near a body of water), the "treated backfill technique" described previously can be used to minimize off-site movement of termiticide.

For houses with a well or foundation drain (or both), an alternative to the liquid soil treatment is a termite bait system. There are several bait products on the market and many companies offer only one brand of termite bait. If you think you would prefer baiting system, you should call several companies and ask about the availability (and feasibility) of using baits for your particular situation.

Controlling termites in houses with wells or drain systems can be more difficult and more labor-intensive whether a liquid or baiting technique is used. Although this added or alternative work may increase the cost of a termite treatment, the environmental concerns justify it. The pesticide label is the law; don't ask or allow the pest control company to do otherwise. If you have a well, cistern, drain or other unusual situation under or adjacent to your house, make sure that the pest control company is aware of its location before any termite treatment is done.

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Pest information and control recommendations presented here were developed for North Carolina and may not be appropriate for other states or regions. Any recommendations for the use of chemicals are included solely as a convenience to the reader and do not imply that insecticides are necessarily the sole or most appropriate method of control. Any mention of brand names or listing of commercial products or services in the publication does not imply endorsements by North Carolina Cooperative Extension nor discrimination against similar products or services. All recommendations for pesticide use were legal at the time of publication, but the status of pesticide registrations and use patterns are subject to change by actions of state and federal regulatory agencies. Individuals who use chemicals are responsible for using these products according to the regulations in their state and to the guidelines on the product label. Before applying any chemical, always obtain current information about its use and read the product label carefully. For assistance, contact the Cooperative Extension Center in your county.

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