Waste Water Treatment : Pipe Labeling Guide

Water Treatment Plant Color Guide

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Pipe TypeType of Liquid / GasCOLOR OF LABEL
Water Lines:Raw waterGreen
Settled or clarified waterAqua
Finished or potable waterDark Blue
Chemical Lines:Alum or primary coagulantOrange
Carbon slurryBlack
CausticYellow w/ green band
Chlorine gas or solutionYellow
FluorideLight blue w/ red band
Lime slurryLight green
OzoneYellow w/ orange band
Phosphate compoundsLight green w/ red band
Polymers or coagulant aidsOrange w/ green band
Potassium permanganateViolet
Soda ashLight green w/ orange band
Sulfuric AcidYellow w/ red band
Sulfur DioxideLight green w/ yellow band
Waste Lines:Backwash wasteLight Brown
SludgeDark Brown
Sewer (sanitary or other)Dark Gray
Other Lines:Compressed AirDark Green
Other PipesLight Gray

Wastewater Treatment Plant Color Coding

Sludge Lines:Raw SludgeBrown w/ black bands
Sludge recirculation or suctionBrown w/ yellow bands
Sludge drw offBrown w/ orange bands
Sludge recirculation dischargeBrown
Gas Lines:Sludge GasOrange (or Red)
Natural GasOrange (or Red) w/ Black bands
Water Lines:Nonpotable WaterBlue w/ black bands
Potable WaterBlue
Water for heating digestors or buildingsBlue with a 6 in. (150mm) red band space 30 in. (760mm) apart
Other Lines:ChlorineYellow
Sulfur DioxideYellow w/ Red bands
Sewage (wastewater)Gray
Compressed AirGreen

Also include an arrow to indicate direction of flow.

To facilitate the identification of piping in plants ad pumping stations it is recommended that the following
color scheme be utilized:

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 or 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 and Coagulant Aids — Orange with Green Band
  • Soda Ash — Light Green with Orange Band
  • Sulfuric Acid — Yellow with Red Band
  • Back Wash Waste — Light Brown
  • Sludge — Dark Brown
  • Sewer — Dark Gray


  • Compressed Air — Dark Green
  • Gas — Red
  • Other Lines — Light Gray

In situations where two colors do not have sufficient contrast to easily differentiate between them, a six-inch band of contrasting color should be on one of the pipes at approximately 30-inch intervals. The name of the liquid or gas should also be on the pipe. I some cases it may be advantageous to provide arrowsindicating the direction of flow.

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