Dye Trace Information and Instructions for Well Owners

Geological Survey Program fact sheet
02/2017
Missouri Geological Survey Director: Joe Gillman
PUB02216

The Missouri Department of Natural Resources performs dye trace testing on a drinking water well to evaluate the quality of their construction or to find the source of a contaminant.

To evaluate the integrity of a well casing, a small hole is dug close to the well. Dye is introduced into the ground.

The department will provide the well owner charcoal packets to be used during the dye trace, along with postage-paid envelopes that should be used to mail the samples to the department.

Four charcoal packets should be placed (one per week) in the back of the toilet tank that is used most often. The toilet tank must be free of cleaners and disinfectants before the recovery packets are introduced, and throughout the duration of the test. It is also important to inform the department if you have a carbon filter in your water line.

During the four weeks of the dye trace the well owner should:

Dyes most commonly used are rhodamine, which is red in color, and fluorescein, which is a lime-green color. In concentrations used for dye traces, both dyes are non-toxic and harmless; however, you may not want to use the water for drinking or washing if the dye can be detected visually.

The department will analyze the packets as they are received and mail the well owner a notice of results after all packets have been analyzed. A positive result would indicate the presence of dye; a negative result would indicate no dye was present in the recovery packet. The presence of dye indicates potential problems with the well’s casing. If dye is detected, a case will be started and you will be contacted by staff to further inspect your well. Should you have questions during the dye trace, call the department’s Wellhead Protection section at 800-361-4827 or 573-368-2165.


For more information
Missouri Department of Natural Resources
Missouri Geological Survey
Wellhead Protection Section
111 Fairgrounds Road
PO Box 250
Rolla, MO 65402-0250
Phone: 573-368-2165
Fax: 573-368-2317
dnr.mo.gov/geology/#water