The Home Drain, Vent & Waste System

Once upon a time, DWV systems were manufactured strictly from cast iron and lead and sometimes copper and brass metals. Today, the products include plastic DWV parts which are especially designed with the do-it-yourselfer in mind. The plastic DWV systems go together as easily as an Erector Set. The products are lightweight, easy to cut and cement, and they are resistant to chemicals and corrosion. The plastic material is also resistant to fungi, bacterial action, and bad soil conditions. In short, plastic DWV systems should be considered when adding any new plumbing to you home that utilizes drain, waste, and vent pipes.

This article deals specifically with the basics of working with plastic DWV materials. These include PVC (polyvinyl chloride), CPVC (chlorinated polyvinyl chloride), and ABS (acrylonitrile-butadiene-styrene).
SPECIAL NOTE: Plastic pipe and fittings are accepted by most national Plumbing Codes, but some local codes will not accept it. Plumbing codes, sometimes called sanitary codes, are necessary to protect the health of homeowners. The restriction on plastic pipe, if any in your community, probably comes from trade groups- not that the products are inferior. Be sure to check with the Plumbing Department of your community government about these codes before you buy product and start working with it.

ASSEMBLY PROCEDURES:
DWV pipe is easy to assemble fast. Here are the procedures you should follow:

1. Measure and estimate the amount and size of pipes and fittings you will need for the project.
   You will find two types of DWV pipe: Schedule 30 and Schedule 40. Schedule 30 pipe is designed to fit inside a 2x4 stud wall. Schedule 40 is designed to fit inside a 2x6 stud wall. Buy accordingly.
   Pipes and fittings are solvent welded. Buy Schedule 30 adhesive for Schedule 30 pipe, or Schedule 40 adhesive for Schedule 40 pipe, or a "universal" cement that may be used for both types.
   Because plastic pipe tends to expand and contract with heat and cold, be sure to allow about 1/4-inch clearance in your measurements when running pipe through floors, ceilings, and framing members.
   Lengths of larger diameter pipe set horizontally should be supported with hanger straps about every 4 feet or so. Support vertical runs of pipes as needed.
2. Measure twice. Cut once. When you are absolutely sure that you have made the right measurements, cut the pipe to size, using a hacksaw with a fine tooth blade set in the saw with the teeth pointing toward the front of the saw frame. The cut should be made on the forward stroke of the saw.
   If you have a miter box, use the box to make square cuts. If not, keep the cuts as square as you can.
3. Deburr the plastic edges made by the saw cuts. We recommend medium grit abrasive (sandpaper) for this job. We do not recommend a knife or file, both of which can cut into the "good" plastic. The trick is to remove just the burrs; try "buffing" the edges lightly with the abrasive paper.
4. Make a "dry" run of the project by assembling the pieces WITHOUT adhesive. If the measurement is a tad "long," you can make cutting adjustments at this point. If the measurement is a tad "short," you can recut a small length to adjust the run accordingly.Also at this time, with a wax China marker, run a short line onto the fittings and the pipe. This mark will be used for aligning the pipe in the fittings when they are assembled with the adhesive. When you're perfectly satisfied that the project fits tightly together, disassemble the pieces.
5. With a fairly narrow clean paintbrush, apply the adhesive to the inside of the fitting and the outside of the pipe. A "medium" coating is plenty. Don't skimp on adhesive, but don't slop it on the parts, either.
6. Assemble the pipe and fittings, using the China marker lines for alignment. Once the pipe is in the fitting, twist the pipe or fitting slightly-about 1/4-inch, or so to "spread" the adhesive. You can offset the China marker lines slightly when you put the pipe in the fitting and then twist either to align the lines.
   Once the pipe/fittings are together, you can't pull them apart. That's why it is so important that your measurements are accurate and the reason for the "dry run." If you have made a mistake, the only way to correct it is to cut out a piece of the run and recouple it with a straight fitting or add more pipe to two fittings.
   If you find yourself in this situation, mark and cut the pipe between the new marks to the measurement of a slip coupling. Slip the coupling onto the pipe, leaving about 2-inches of the pipe ends exposed for the cement. Heavily coat the pipe with adhesive and slip on the coupling. Then slide the coupling into position.

PROJECT DATA/BACKGROUND:
Since we don't know what DWV project you will undertake, we can't give you specific DWV design and detail information. However, on the next pages you will find several typical projects involving DWV products. Hopefully, you can use this data to help plan and construct your project.

As background, explore the Plumbing Department of a home center, looking and handling the various DWV products on display. By doing so, we think that you'll become better acquainted with these products, and, therefore, see how they can be adapted to specific projects that you have planned for your home.

When figuring pipe size remember that pipes too small can't carry the drainage load. Pipes too large will tend to clog. "Average" drainage pipe sizes are:

Toilet: 3 inch pipes.
Bathtubs: 2 inch pipes.
Kitchen sinks: 1 1/2-inch pipes.
Lavatory: 1 1/2-inch pipes.
Floor drains: 1 1/2-inch pipes.
Laundry drains: 1 1/2-inch pipes.
Soil pipe: 3 inch pipes.
Sanitary tees: 3 inch pipes.
Vent stacks: 3 inch pipes.

Be sure to check local plumbing codes concerning sizes. The list above must be considered "average.

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Comments consumer I would like to use 2" abs dwv pipe under a liner type swimming pool. Will this sch 40 pipe stand up to the weight of 5' of water? Thanks, Matt #2 - matt - 04/03/2009 - 15:52 plumber it was verry helpfull to me with with my work and i will tell my friends about it. #1 - ralston oldacre - 02/08/2009 - 13:21 Helper Is there a site on the www that lists with a picture the basic ABS DWV parts such as elbow, T-Y, coupler, P-Trap (several) etc #0 - C Clements: code@dunnottar.ca - 06/09/2008 - 11:35 Name Title Comment To prevent automated Bots form spamming, please enter the text you see in the image below in the appropriate input box. Your comment will only be submitted if the strings match. Please ensure that your browser supports and accepts cookies, or your comment cannot be verified correctly.