Plumbing Piping Symbols Cold water Soft cold water Hot water Storm drain Drain or waste above ground Vent Drain or waste below ground Sprinkler main Sprinkler branch and head Compressed Air Vacuum Gas Sewer - Cast Iron Sewer - Clay Tile Sewer - Plastic Air Conditioning Piping Symbols Condensed Water Supply Condensed Water Supply Return Chilled Water Supply Chilled Water Supply Return Refrigerant Liquid Refrigerent Discharge Make-up Water Humidification Line Heating Piping Symbols Fuel Oil Supply Hot Water Heating Supply Hot Water Heating Return Low-Pressure Steam Medium-Pressure Steam High-Pressure Steam