Abstract: A dye strip for tracing liquid flow comprises a water-soluble paper impregnated with tracing dye. The dye-impregnated paper is in a dry form prior to use. A process for preparing the biodegradable dye strip calls for providing a water-soluble paper, communicating the water-soluble paper with liquid dye to absorb said liquid dye into the paper and forming a resulting dye-impregnated paper. The resulting dye-impregnated paper is dried. The product can be placed into a vat containing liquid. Dye diffuses from the paper into the liquid to form dyed liquid. The flow of the dyed liquid is then observed.