uPVC pipe is pipe that is specifically free of plasticizers and is100% PVC. To improve flexibility it is possible to add a small amount of plasticizers in the pipe put those plasticizers tend to leach out of the pipe walls in certain applications. Because of the concerns of plasticizers being ingested by people and an animals it is better to ensure that only uPVC pipe is used in potable water applications. For the purpose of drain pipe it is acceptable to use straight PVC pipe.
CPVC as PVC’s cousin. They are similar in many ways, but they shouldn't be used interchangeably. Both are made of the same basic elements with one distinguishing factor. CPVC is altered by a free radical chlorination reaction that effectively increases the chlorine content of the material. This difference in makeup allows CPVC to withstand a wider range of temperatures. This is why many building codes require the use of CPVC as opposed to PVC for use in hot water applications. The ASTM standard allows PVC to be used in applications not exceeding140 degrees F. Temperatures over this can cause softening of the material and weakening of joints. CPVC on the other hand can handle temperatures up to200 degrees F.