Dye Trace Information and Instructions for Well Owners

Geological Survey Program fact sheet
Missouri Geological Survey Director: Joe Gillman

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

To evaluate the integrity of a well casing seal, a small hole is dug close to the well. Dye is injected

into the ground via the hole. The dye will migrate down the borehole adjacent to the well casing. If a satisfactory grout seal is present, the dye will be blocked from entering the well below the casing.

Department staff will provide the well owner four dye recovery packets (composed of activated charcoal) to be used during a dye trace, along with pre-addressed, postage-paid envelopes that should be used to mail the samples. Four packets should be placed (one per week) in 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 also is important to inform the staff if you have a carbon filter or UV light on your water line.

During the four week dye trace test, 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 is visible.

Staff 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, you will be contacted by the staff and provided further instructions. If you have questions during the dye trace, or if you see dye, please call 573-368-2165 or email welldrillers@dnr.mo.gov.

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