Horobin also offers Pipe and Drain Tracing Dye. Tracing Dyes are supplied in 200gram Poly-jars in a range of 6 colours – GREEN FLUORESCEINE, RED, BLUE, ORANGE, YELLOW & VIOLET and are used for detecting the flow of water in drains or pipes, identifying individual drain runs into a common gully, and tracing leaks in pipes. Dyes are non-toxic and odourless and are approved by the National rivers Authorities, Water Companies and Local Authorities. Green Dye contains 50% Fluorescence. The other colours are made from 100% food grade products.