Water pipes used in the plumbing system and conduit pipes used in the electrical system are made from the same material. So, you might think of interchanging these pipes and using conduit for plumbing.
But can you use a conduit for the water pipe? Not at all. PVC conduit is designed to protect electrical wires from abrasion or corrosion. They aren’t suitable for use as water pipes.
Learn more about the differences between PVC pipes and PVC conduits to understand why you can’t use conduits for water pipes. You will also be aware of different PVC conduits schedules for various purposes.
PVC stands for Polyvinyl Chloride. It is a synthetic resin with high chemical resistance. Various pipes and fittings are made of PVC. PVC plumbing pipes, commonly known as PVC pipes, are used in plumbing. And these can be a good alternative to copper pipes, which are pretty expensive.
But PVC conduit is a type of rigid plastic pipe that is also made from PVC but isn’t the same as regular PVC pipes. Plumbing PVC pipes are typically white, but PVC conduits are gray. There can be other colors depending on what additives are added to the composition.
Though both pipes are made of the same material, you can’t use conduit for water pipes. Each of these pipes is designed to serve a specific purpose depending on their characteristics. So, they aren’t interchangeable.
See the reasons below why you can’t use electric conduit pipes for water plumbing.
PVC pipes or plumbing pipes transport water from one place to another within the system. Water pressure builds up inside these pipes, so they need to withstand the pressure. PVC pipes are tested using Standard Test Method and rated based on their performance in the pressure test. You will see the ratings on the pipe.
But PVC conduit isn’t designed to withstand that much pressure. Also, no pressure test is done for these pipes. If you install PVC conduit in a plumbing system, water will start leaking soon.
Electrical conduit pipes are used to protect electrical wires or connections from corrosion, heat, spark, etc. So, they don’t need as much wall thickness as plumbing PVC pipes. You can easily bend conduit pipes without breaking them, which helps using them in tight situations.
But PVC pipes are specifically designed to carry water. So, they have a higher wall thickness than conduit pipes. You can’t bend PVC pipes so easily because of the thicker wall, and it makes them suitable for use in plumbing.
PVC pipes are typically used indoors. So, they need more to be waterproof than UV-resistant. But conduit pipes aren’t tested for water resistance. Instead, they are tested for UV resistance. So, conduit pipes are more suitable for outdoors, and they can withstand long-term UV exposure.
But if you use PVC pipes outdoors, they will degrade from long-term UV exposure. It makes them brittle and develops cracks. So, these pipes should not be used interchangeably.
Conduit pipes usually have flares on the ends. So, joining two conduit pipes together doesn’t require any coupler. Also, these joints aren’t typically waterproof. But PVC pipes used in plumbing require couplers to join together.
And those joints should be sealed with PVC cement so that the joint is waterproof. This is another important reason for not using conduits for water pipes.
Conduit refers to systems having multiple electrical conductors. And conduit pipes are used to protect them from exposure to external threats. They also prevent fire from the conductors. Here are some common use cases of PVC conduit pipes.
- Protecting electrical conductors from UV, heat, or other threats
- Preventing electrical wiring from abrasion on rough surfaces
- Creating right-angle bends for conduit runs
- Making the electrical system easier to reach for maintenance
- Neatly organizing electrical conductors to avoid accidents
PVC pipes are categorized into three schedules according to ASTM or the American Society for Testing and Materials. The specification of PVC pipes requires them to be used with the distribution of pressurized liquids only.
Here is a size chart for schedule 40 PVC from The Engineering Toolbox. Check it out.
The most critical part of the size chart is the minimum wall thickness. It can never be lower than what is mentioned in the chart to ensure the system is suitable for liquid distribution. Here is a size chart for the schedule 40 conduit from Everett J. Prescott.
As you might already see, the minimum wall thickness is the same for both pipes. Still, a conduit isn’t suitable for water pipes because they aren’t pressure tested. According to ASTM, you can’t use a conduit for a water pipe.
Check answers to some frequently asked questions about PVC conduit.
A: Plumbing PVC pipes are commonly known as white PVC due to their color. You can’t use white PVC for electrical conduit because these pipes can’t be bent. Also, they aren’t suitable for outdoor use.
A: Yes, PVC conduit is permitted to use inside walls or floors. You can even bury PVC conduit in concrete, especially underground.
A: Though Schedule 80 PVC conduit is designed for heavy-duty work, it isn’t suitable for water pipes. You can use it for electrical systems in commercial buildings.
PVC conduit is easy to work with, so many people can be tempted to use it for water pipes. But can you use a conduit for the water pipe? No, you can’t. Though conduit and plumbing PVC pipes are made of the same material, their use cases are different.
Conduit pipe isn’t tested and rated to withstand water pressure, so you shouldn’t use it for water pipe. Always check the minimum wall thickness and pressure rating of PVC pipes before using them in plumbing.