DIY Installing Plumbing for a Toilet

Written by paul massey
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DIY Installing Plumbing for a Toilet
(Brand X Pictures/Brand X Pictures/Getty Images)

Many residential remodelling projects include the addition of a new toilet. Before the toilet can be installed, the waste drain line and water supply line must be run to the new toilet's location. Residential waste drainage lines are most commonly assembled out of acrylonitrile butadiene styrene pipe, a black plastic piping commonly referred to as "ABS," while water supply lines are fabricated out of copper piping. Both piping systems are relatively easy to install by following a basic procedure to fulfil the toilet's supply and drainage requirements.

Skill level:

Things you need

  • Tape measure
  • Tubing cutter
  • Soldering torch
  • Flux-core solder
  • 1/2-inch copper tubing
  • Insulated piping hooks
  • Toilet stop valve
  • 4-inch diameter ABS pipe
  • 4-inch toilet flange
  • ABS cleaner
  • ABS cement
  • Jigsaw or reciprocating saw
  • 2-inch plated wood screws

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    Install the Water Supply Line and Toilet Valve

  1. 1

    Turn off the main water supply to the house at the main service valve, typically found at the exterior of the house or in a concrete box near the street.

  2. 2

    Install a 1/2-inch copper water line to the toilet location, inserted up through the wall's bottom plate at approximately 8 inches to the left of the toilet location centerline. The water line supplying the sink is an excellent nearby connection point. Be sure to use a 90-degree elbow or stub-out fitting to extend the water line through the wall surface plane, parallel to and approximately 8 inches above the finished floor surface for a standard valve location.

  3. 3

    Secure the copper water piping to an adjacent wall stud will an insulated pipe hook or solder the line to a copper nailing strap secured to the wall studs at both sides of the water line position.

  4. 4

    Install a toilet stop valve and trim ring to the end of the 1/2-inch copper water line stub-out, making certain to trim the copper pipe so that the stop valve is positioned flush or nearly flush with the wall surface.

    Install the Waste Line and Toilet Flange

  1. 1

    Connect a 4-inch diameter ABS drain line to the main waste drain line nearest the toilet location, then extend the new drain line to the toilet location. If the new toilet location is part of an added full bathroom, the sink and bathtub drainage can tie into the toilet waste drain too. Make certain to maintain the minimum slope required by the building code and that a clean-out fitting is installed at the point where the waste drain line turns vertically to rise to the bathroom floor.

  2. 2

    Cut a 6-inch diameter hole in the bathroom subfloor surface, verifying the waste drain location with the manufacturer's specifications for the toilet being installed. The finished end of the ABS piping should centre through the subfloor at 12 inches from the bathroom's rear wall, 18 inches minimum to either side from a wall or cabinet, and flush with the subfloor surface.

  3. 3

    Secure support beneath the subfloor for the drain line using standard ABS strapping or blocks to hold the drain piping in position.

  4. 4

    Install a standard toilet flange to the end of the ABS waste drain pipe and secure the flange to the subfloor surface using plated wood screws. The necessary supply and drain plumbing is now complete for the new toilet.

Tips and warnings

  • Dry-fitting the ABS waste line and fittings prior to final gluing and the copper water line prior to final soldering helps to insure accurate alignment and locating of the lines.
  • As a precaution, the copper water line should be temporarily capped and filled with water to check for any leaks before completing the wall finish in the bathroom.
  • Installing the rough plumbing lines for a new toilet location requires a basic understanding of and ability to solder copper fittings, as well as an understanding of acrylonitrile butadiene styrene piping components and residential drain systems.
  • Local, state and national plumbing codes have specific requirements regarding the design, materials and locations of plumbing fixtures and waste drain lines, and you should consult your local building department to insure compliance.

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