They are not interchangeable
PVC, UPVC and CPVC are all polyvinyl chloride based, but the additives and chlorination change what each one can handle. Choosing by price alone is the most common cause of premature failures in plumbing lines.
The safest way to specify is by the Indian Standard the pipe is manufactured to, not by the trade name printed on it.
UPVC — unplasticised, for cold water and drainage
UPVC pressure pipes are made to IS 4985 in pressure classes from 2.5 to 10 kgf/cm². UPVC soil, waste and rain water (SWR) pipes are a separate family made to IS 13592 in Type A (ventilation and rain water) and Type B (soil and waste) grades.
SWR pipe is a gravity pipe. It is not rated for pressure and should never be substituted into a pumped or mains line.
CPVC — for hot water
CPVC is chlorinated to raise its temperature tolerance, and pipes to IS 15778 are rated for continuous hot water service up to 93 °C. This is why geyser, solar and hospitality hot water lines are run in CPVC rather than UPVC.
CPVC uses its own one-step solvent cement. UPVC cement on a CPVC joint is a defect, not a shortcut.
Quick selection guide
- Cold water mains and distribution: UPVC pressure pipe to IS 4985, class chosen from the working pressure
- Soil, waste, rain water: UPVC SWR to IS 13592, Type A or Type B
- Hot and cold plumbing inside a building: CPVC to IS 15778, SDR 11
- Buried drainage and sewerage: structured wall DWC pipe to IS 16098 Part 2
Before you order
Have three things ready: the diameter, the pressure class or ring stiffness required, and the jointing method the site will use. With those, a supplier can confirm what is available and quote accurately in one pass.