PVC vs. CPVC Before PEX came around, PVC (Polyvinyl Chloride) and CPVC (Chlorinated Polyvinyl Chloride) were the primary plastics used in plumbing. Both PVC and CPVC are still widely used and found in countless homes - but how much does that extra 'C' change things? Differences Between PVC and CPVC C is for Chlorinated: CPVC is basically just PVC with more chlorine (via an additional chemical reaction in the manufacturing process). How much more depends on the manufacturer, but it can be as much as a 20% increase. The additional chlorine in the pipe itself has no effect on the water moving through it. Temperature Resistance: PVC is safe for residential water applications below 140°F, while CPVC is safe at temperatures up to 200°F. Temperatures above those limits will result in softening of the pipe and weak joints, which will lead to leaks and failure. Sizing: PVC is sized according to IPS (Iron Pipe Size) standards. CPVC can be IPS-sized, but it's more commonly found sized to CTS (Copper Tubing Size) standards, which are completely different from IPS. PVC and CPVC cannot be joined together. Color: You can find PVC in white (schedule 40) and gray (schedule 80), as well as the more rare purple, which indicates reclaimed or recycled water that is unfit for drinking, and usually used for landscaping and irrigation. CPVC is either an off-white, yellowish cream color (schedule 40), or light gray (schedule 80). You can always check the information that's printed directly on the pipe if there's any question. Price: PVC is usually less expensive than CPVC, but not by a whole lot. Both are much less expensive than metal or PEX. Please note: The following overview is based on Universal Plumbing Code (UPC) guidelines - local plumbing codes can supercede this, so be sure to check with your local authorities before embarking on anything. PVC Applications A typical application for PVC is the service line, which goes between the water main and the home (and is the homeowner's responsibility). CPVC is also approved for underground use, but is more expensive and doesn't offer any benefits in this particular situation. Another common use for PVC is in the Drain-Waste-Vent (DWV) system that carries wastewater to the sewer, regulates air in the pipes, and removes dangerous gases from the home. PVC is also a popular choice for yard irrigation and sprinkler systems. Flexible PVC is often used for pool, spa, or hot tub installations where rigid piping may not fit as well or require more joints. CPVC Applications While CPVC can technically do anything PVC can, its use in the home is usually limited to indoor water distribution (the system of pipes that carry water to fixtures around the house). CPVC is ideal for homes with corrosive water or soil conditions. Note: Plumbing code prohibits PVC from being used for indoor distribution because of its lower heat resistance (140°F). Even if your water heater is set well below 140°F, the actual output temperature from the heater can fluctuate wildly, opening the door to pipe damage. Why not simply limit its use to cold-water piping? Because there's no way to guarantee hot water won't make its way into cold-water pipes. CPVC is widely used in fire sprinkler systems thanks to its heat resistance, low price, durability, and ease of installation. Because it's a plastic, it's relatively unreactive and will not rust like metal options - a very good thing for a safety system. Pro Tip: Both PVC and CPVC require primer and solvent cement ("glue") in order to be joined to fittings. These products are not interchangeable between the two plastics - always check the label to be sure you're using the proper product for the material.