From Article 2.14 of the Ten States Standards
Water lines
raw or recycle olive green
settled or clarified aqua
finished or potable dark blue
Chemical Lines
alum or primary coagulant orange
ammonia white
carbon slurry black
caustic yellow with green band
chlorine (gas and solution) yellow
chlorine dioxide yellow with violet band
fluoride light blue with red band
lime slurry light green
ozone yellow with orange band
phosphate compounds light green with red band
polymers or coagulant aids orange with green band
potassium permanganate violet
soda ash light green with orange band
sulfuric acid yellow with red band
sulfur dioxide light green with yellow band
backwash waste light brown
sludge dark brown
sewer (sanitary or other) dark gray
compressed air dark green
gas red
other lines gray