Frequently Asked Questions How safe are Dyes and Tracers? The use of dye is not a preferred method to evaluate the condition of a septic system. Dyes and tracers are often used to locate leaks and to determine whether the drainfield is clogged and if the system has contaminated nearby wells, other potable water sources, or surface waters. One drawback to this method is that some dyes are thought to be carcinogenic and may contaminate nearby water sources. Dyes sometimes do not become visible for hours or days or may not appear at all, even in systems that are malfunctioning. Improper testing with dye may cause hydraulic overloading and can potentially harm drainage systems. Return to FAQ's