How to Do Plumbing on Drains & the Angles You Need


Almost all communities require basic plumbing be installed by professionals. That involves running the main water supply lines into a house and connecting a central drain that ties to the sewer line or a septic tank. A main drain system will be installed during initial construction, usually under a basement floor or concrete slab foundation. A homeowner in some instances can install and usually can replace specific drain elements, such as to a kitchen, bathroom or utility sink. The material of choice today is plastic, usually polyvinyl chloride or PVC pipe.

Things You'll Need

  • Sketch pad
  • Pipe and connectors, elbows and angles
  • Hack saw
  • PVC cement
  • P-traps
  • Draw a rough diagram of the plumbing plan, to show the routing for pipes from a sink to a main drain. Locate cabinet sides, walls and other obstructions that the pipes must go through or around. Indicate the angles for connections, to go around obstacles or just veer from a center sink drain to a line inside a wall. Locate vents; all plumbing drains must vent to the outside or be equipped with special interior venting.

  • Check plumbing supply houses for angled connectors, at 90-degree, 45-degree or other angles. Use a tape measure to figure the distances for straight run pipes between connectors, from a kitchen sink, for instance, to a pipe leading to the main drain. Mark all the connections on your plans, showing every turn. Cut PVC pipe for straight runs to length with a hack saw and connect it with the appropriate angled fasteners.

  • Combine elbows and angled connectors to work around obstacles horizontally and go down through walls to main drains. Form almost any shape by blending angled and elbow connectors, with straight pipes between as needed to extend an elbow or angle.

  • Dry fit pipes together to make sure all the elements fit. Remove sections one at a time and cement them with PVC cement; apply cement to the outside of one element, the inside of the connecting piece, slide the two together, twist them slightly, then let the cement set. Use cemented connections up to the point under a sink or other drain where you will install a P-trap.

  • Install P-traps, actually U-shaped pipes, with screw-on compression connectors under every sink or other basic drain point. Buy the P-trap of the correct size for the pipes being drained. Slip the pipe from the sink or other drain into one end of the P-trap and fasten it; the connector has a plastic washer that expands to seal the joint between the two pipes. Put the pipe leading to the main drain in the other end of the P-trap and fasten it.

Tips & Warnings

  • All drains must have a P-trap, which retains water in the bottom to block odors from coming back up the pipe, and vents, which provide outside air pressure to release odors to the outside. All drains also need clean-outs, covers that can be removed to get access to the drain for cleaning.
  • Vary pipe size to fit the drain. Most sinks are drained with 2-inch pipe, toilets usually with 4-inch, but these can vary.

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