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Can You Join ABS to PVC? Installation, Facts, & FAQ

PVC pipes

ABS and PVC plastic are the two most common types of pipes in American plumbing. Since they are so common, many people wonder if you can connect the two and use them in the same system. The short answer is yes, but only under certain conditions. Keep reading as we provide the best methods to connect these two kinds of pipes.

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How Can I Connect ABS to PVC?

Transition Coupling

The only approved way to connect a piece of PVC pipe to an ABS pipe is to use transition coupling. It’s a type of fitting that uses a cylindrical rubber gasket with an internal pipe stop and a metal shield with two clamps that you screw together to tighten the transition coupling and create a watertight seal between the two different kinds of plastic.

CPVC pipes and fittings
Image Credit: Effect Box, Shutterstock

How Do I Install Transition Coupling?

  • When setting up your pipes, cut them so there is a 1/8-inch gap between them. The rubber pipe stop inside the transition coupling fills the gap between the two pipes, creating a tight seal.
  • Loosen the metal jacket of the coupling, and slide it over one of the pipes.
  • Roll the rubber gasket back, and push it onto one of the pipes, then roll back the other side and attach the second pipe. When the pipes are in position, unroll the rubber gasket.
  • Slide the metal jacket over the rubber gasket, and tighten the clamp screws to create a watertight seal.
  • Test it for leaks by running water through the joint.

What Is Transitioning Glue?

If you shop at your local hardware or home improvement store and look at the different kinds of glue, you will likely find one that states that it’s for connecting PVC and ABS plastic, which might seem contradictory. However, transitioning glue is not for connecting different plastic pipes inside a home, where the water is under pressure. Instead, it’s for connecting a large PVC system to a large ABS system that is not under pressure. This usually occurs when the PVC system inside the home meets the ABS pipes used by the city sewer. Since these drainpipes are not under pressure, transitioning glue is a legal way to connect them.

plumber applying glue to grey pipe
Image Credit: Phovoir, Shutterstock

What If I Use Transitioning Glue to Connect ABS and PVC Pipes by Accident?

If you use transitioning glue to combine PVC and ABS plastic inside a home, where the water is under pressure, you might get a warning from a building inspector if they see it. That said, the bond that you create using transitioning glue, especially if you combine it with purple primer, is quite strong and unlikely to cause any problems. The inspector will likely inform you that you did it wrong but won’t make you fix it. Another possible downside to using the transitioning glue is that it can be difficult to separate the parts later if needed, due to the strong bond.

What Is Purple Primer?

Purple primer is a purple liquid that you apply to PVC pipe to prepare it for gluing. It softens the outer shell slightly, so you get a stronger bond once the glue dries, and it will significantly increase the strength of the bond between PVC and ABS plastic.

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The best way to join ABS and PVC plastic pipes is by using a transition-coupling clamp to connect and seal the two pipes according to the building code. The rubber gasket creates a tight waterproof seal, and the metal shield creates a rigid connection that won’t bend or break. Some people might suggest using transition and glue, but you can only use it for systems with very little or no pressure, like where your house connects to the sewer system. However, if you use it by accident, it will likely work just as well, though you might get reprimanded by an inspector or professional plumber if they see it.

Featured Image Credit: Carlo Toffolo, Shutterstock


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