Colour coding is the accepted idea of designating particular colour cleaning products & processes to consistent colour schemes. Its purpose is to segregate equipment & procedures in order to prevent infection & cross contamination. Follow the `Golden Rules` below to use colour coding successfully & help protect health.
Red High Risk Sanitary Areas such as toilets, urinals & washroom floors. Blue Low Risk General Area such as desk tops, window ledges, dusting & polishing. Green Catering Departments Food processing, food services & bar areas. Yellow Washbasins & surfaces including tiled walls, mirrors, glass & metal.
Its not "Law" just good practice. You can always adapt to suit your needs such a Blue for Catering.