Drain, Waste, and Vent (DWV) System

Drain, Waste, and Vent (DWV) System Overview

• The Drain, Waste, and Venting (DWV) System provides collection of sanitary soil (solid particles) and waste (fluids) within a building.
• It also manages the discharge of these products outside the building to a septic system.

General Design Rules

• Pipes should take the shortest possible route to the house sewer or the sanitary system's terminating point.
• Control components like clean-outs, traps, and vents should be located strategically for efficient circulation.

Subsystems of the Sanitary System

• Waste Collection System
• Ventilation System

Components of Sanitary System

• Vent Stack
• Vent Pipe
• Shutoff Valve
• Lavatory Drain
• Toilet Drain
• Soil Stack
• Cold Water Supply
• Hot Water Supply
• Overflow Pipe
• Trap
• Tub Drain

Waste Pipe

• Conveys wastewater or liquid waste free of fecal matter.

Vent Pipe

• Ensures air circulation in a plumbing system.
• Relieves negative pressure exerted on trap seals.

Trap

• A fitting that provides a liquid seal to prevent backflow of foul air or methane gas.
• The liquid seal doesn't affect sewage or wastewater flow.

Stack

• The vertical main of a soil, waste, or vent piping system.
• It extends through one or more stories and through the roof.

Branch

• Any part of the piping system other than a main, riser, or stack.

House/Building Drain

• The lowest horizontal piping of a plumbing system receives discharges.
• It conveys sewage outside of the building to the house sewer.

House/Building Sewer

• Extends from the house drain at a point of 0.60 meters from the building's foundation wall.
• It goes to the junction with the street sewer or discharge point.

Minimum Slope for Drainage

• A minimum slope or pitch of horizontal drainage pipe is 2% or 20mm/m (¼" per foot).
• Pipes 102 mm dia or larger may have a slope of not less than 1% or 10mm/m (1/8" per foot).

Permissible Traps

• Common P-Trap
  • Used for lavatories, kitchen sinks, laundry tubs, and urinals.
  • Made of PVC, nickel, chrome plated brass, or galvanized malleable copper.
• Deep Seal P-Trap
  • Water seal is about 2x the size of the common P-trap.
  • Used for extreme conditions
• Stand Trap
  • Used for fixtures built low in the ground with little space for a foundation and trap like slop sinks.
  • Serves as water seal and enhances structural support for the fixture.
• Running Trap
  • Used within the line of the house drain.
  • it is Sometimes used with a washing machine waste outlet or for dishwashers.
• Drum Trap
  • Has a large diameter (around 0.16m).
  • Used for fixtures that discharge significant water, such as bathtubs, showers, or floor drains.
  • Cylindrical container installed between the drain and the plumbing fixture.
  • The trap contains a water seal which prevents sewer gases from entering the building.

Elements of Sanitary System

• Soil Pipe
  • Any pipe that conveys the discharge of water closets, urinals, or fixtures.
• Stack
  • A general term for any vertical line of soil, waste, or vent piping.
• Soil Stack Pipe
  • A vertical soil pipe conveying fecal matter and liquid waste.
• Stack Vent
  • An extension of a soil or waste stack above the highest horizontal drain connected to the stack.
• Vent
  • A pipe or opening ensuring air circulation to reduce pressure on trap seals.
• Unit Vent
  • Arrangement of venting where one vent pipe serves two traps.
• Wet Vent
  • That portion of a vent pipe through which liquid waste flows.
• Branch
  • Any part of a piping system, other than the main riser or stack.
• Main
  • The principal artery of the system to which branches connect.
• Branch Vent
  • Vent pipe connecting from a branch of the drainage system to a vent stack.
• Waste Pipe
  • Pipe conveying only liquid wastes free of fecal matter.
• Drain
  • Sewer/pipe used for conveying groundwater, surface water, wastewater, or sewage.
• Sewer
  • Conduit for carrying sewage and waste liquids.
• Sewage
  • Liquid wastes conducted away from buildings/structures, including stormwater.
• Sewerage
  • Term covering all construction for collection, transportation, pumping, treatment, disposal of waste.
• Cleanout
  • Sleeve joined to an opening where a plug can be removed for cleaning or examining the pipe interior.
• Trap
  • A fitting that prevents air/gas/vermin passage, doesn't materially affect sewage flow.
• House Drain
  • Receives discharge inside a building and conveys it to the house sewer.
• House Sewer
  • Extends 4-5 feet from foundation wall to where the building connects to another sewer.
• House Trap
  • Trap connected to the lowest horizontal piping or House Drain.
• Relief Vent
  • Vent that provides circulation of air between drainage and vent systems.
• Public Sewer
  • Common sewer controlled by the public authority where all abutters have equal connection rights.
• Siphonage
  • Suction caused by flow of liquid in pipes.
• Spigot
  • The end of a pipe fitting into a bell, or a synonym synonymous with faucet.
• Seal
  • Vertical distance between the dip and crown wire of a trap.
• Roughing-In
  • Installation of all pipes within partitions and under floors.
• Finishing
  • the setting of fixtures.
• Sump
  • Pit/receptacle at a low point to which liquid wastes are drained.
• Sleeve
  • Sheet metal placed when concrete is poured to accommodate future plumbing pipes.
• Pipe Chase
  • Space to accommodate pipes.
• Plumbing Fixtures
  • Receptacles or installed devices supplied with water or discharge into the drainage system.

Vents

• Dry Vent
  • A vent that does not carry liquid or water-borne wastes.
• Wet Vent
  • Portion of a vent pipe through which wastewater flows.
• Stack Vent
  • Extension of a soil or waste stack above the highest horizontal drain, connected to the stack.
• Vent Stack
  • Vertical pipe providing air circulation from the soil and waste system while preventing fumes.

Downspout

• Usually smaller and more suited for residential properties.
• Manages less water flow.
• Often drains water at the surface away from the property.

Leader

• A vertical pipe transporting rainwater from roof gutters to a storm drain or sewer system.
• Larger and commonly inside buildings ideal for large structures
• Is typically connected to a city's storm sewer system.