The Dye Tracing Pages

Why Use Fluorescent Dyes?

Fluorescent dyes make excellent tracers for a variety of reasons, including: 1. They are water soluble. 2. They are hightly detectable (some below 1 part per trillion). 3. They have extremely low toxicity ratings. 4. They are inexpensive. 5. They are fairly stable in a normal water environment. 6. They have been used successfully for tracing for over 100 years. Over the past few years there has been some concern about the toxicity of the dyes used for groundwater tracing. Two points need to be made addressing these concerns: 1. Fluorescent dyes are typically used in low concentrations due to their excellent detectability. Even at high concentrations, these dyes maintain their extremely low toxicity ratings. Chlorine and Fluoride are both highly toxic substances that are added to drinking water to kill off microrganisms that may be present in the water and to strengthen teeth. People drink chlorinated and fluoridated water every day. People do not drink untreated groundwater with dye present on a daily basis. 2. Groundwater tracing usually occurs at sites where the groundwater is contaminated with enough toxic substances to be deemed unsafe to drink. The addition of a small quantity of dye into this water in order to map out its flow routes is not going damage the water quality in any appreciable manner. If fact, if the dye does show up in some person's drinking water, it is probably a good thing.