Drain Pipe Plumbing a.k.a.
Drain-Waste-Vent Plumbing (DWV) using PVC or ABS


Don't avoid plumbing your drain simply because the pipes are large. Using PVC or ABS drain pipes allows your drain system to go together almost as easily as smaller water supply pipe and fittings! PVC and ABS drain pipes are also light and come in convenient 10 foot lengths.

A plastic drain system excels at DWV service. PVC (polyvinyl chloride) especially as it has chemical and corrosion resistance. In fact, PVC pipe is so chemically resistant it's used in chemical plants to convey concentrated acids and strong alkaline solutions. These would quickly destroy metal drain pipe. Vinyl drain pipe is also unaffected by salt solutions, alcohols, and many other chemicals. You can pour drain cleaning chemicals down your PVC drains with full assurance that the pipes are completely impervious to them.

ABS (acrylonitrile butadiene styrene) on the other hand, can suffer stress cracking in the presence of fats, greases, and acids. Both piping materials will take all the hot drain water you could want to put down it.

Roughing in a drain system

Rough plumbing is done after the sub floor, roof flashings, and the finished roofing material --shingles-- have been installed. Neither insulation nor finished wall, floor, and ceiling materials should be in, however. In a concrete slab structure, all under slab plumbing should have been roughed in before the slab was poured. Rough plumbing begins with the DWV system. Water supply roughing follows, since the smaller tubes can be fitted around the drain piping.

Planning your drain system is the first step. Toilets are the chief DWV fixtures to plan for, because they need larger 3" soil pipes.

Click here to view the 5 basic plumbing layouts

The five basic plumbing layouts show compact plumbing setups without additional venting. They will give you an idea of piping arrangements that can be used. Number 1 is the plumber's ideal fixture arrangement with the washbasin and tub/shower on either side of the toilet. That way, toilet, washbasin, and bathtub/shower can all drain into the vent stack behind the toilet and can also be vented there. Waste pipe runs are short and direct.With the washbasin draining above the floor directly into the vent stack, its liquid wastes wash down past the toilet's drain, helping to keep those pipes open.

Fixture drains and stacks are shown on the plans as white circles, large ones for toilets, smaller ones for the other fixtures. Drains appear as black lines, thick for 3" toilet and main drains, thinner for 1 1/2" and 2" tub/shower waste branches to the mains. Vent stacks are shown as white circles within partitions.

It's ideal to have another drain-using fixture back up to a bathroom. For example , a kitchen sink, laundry tub, or a second bath or half-bath goes back to back with the bathroom. This makes double use of the first bathroom's DWV and water supply pipes.

In any case, the plumbing should be installed to accommodate the fixtures. It's easy with plastic drain pipe and fittings, no matter how much piping is being installed.

Make sure your DWV planning takes into account the local plumbing code and what must be done to meet its requirements.

For step-by-step instructions on plumbing your own drains, purchase Genova's Do-It-Yourself Plumbing book!

Visit the Genova Products website for more information on Genova's DWV products.

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