How we supply it: uPVC pipes and fittings are arranged through a partner plumbing dealer who quotes, supplies and bills them and pays us a referral commission. For buried yard and sump lines, the bedding sand or crusher dust can come from us on a load you are already ordering.
In one line: uPVC (unplasticised polyvinyl chloride) pipe is a rigid plastic pressure pipe for cold water, sold by outside diameter and pressure class and joined with solvent cement or rubber-ring sockets.
What uPVC pipe is for
uPVC (unplasticised polyvinyl chloride) pipe is a rigid plastic pressure pipe for cold water, sold by outside diameter and pressure class and joined with solvent cement or rubber-ring sockets.
It does not rust or scale, which is why it replaced GI pipe for most cold lines. It softens with heat, which is why it never goes on a hot line.
Pressure classes under IS 4985
| Class | Working pressure | About |
|---|---|---|
| Class 1 | 2.5 kgf/cm² | 25 m head |
| Class 2 | 4 kgf/cm² | 40 m head |
| Class 3 | 6 kgf/cm² | 60 m head |
| Class 4 | 8 kgf/cm² | 80 m head |
| Class 5 | 10 kgf/cm² | 100 m head |
| Class 6 | 12.5 kgf/cm² | 125 m head |
Which class for which line
| Line | Typical choice | Note |
|---|---|---|
| Sump to overhead tank (pump delivery) | uPVC Class 3 or 4 | Margin for pump surges and knocks |
| Buried yard and garden lines | uPVC Class 3 | Bedded in sand |
| Borewell casing | Casing pipe to IS 12818 | A different product from pressure pipe |
| Hot water and concealed bathroom lines | CPVC, not uPVC | See CPVC |
| Mains connection | As the water board specifies | Ask before buying |
Laying buried lines
Depths and bed thickness above are typical house-site values.
- Dig the trench to a depth where traffic and garden digging will not reach the pipe, commonly 450–600 mm.
- Lay a 75–100 mm bed of sand or crusher dust, free of stones.
- Joint the pipes, support bends and tees so they cannot move under pressure.
- Pressure-test before backfilling.
- Surround the pipe with more sand or dust, then backfill with soil free of rubble.
Checks on uPVC pipe
- The print should show IS 4985, the class, outside diameter and batch.
- Measure wall thickness at a cut end and compare it with the class for that size.
- For drinking water, confirm the pipe is the potable-water grade.
- Check solvent-welded joints are made clean and fully pushed home.
- Hold the test pressure for the agreed time before backfilling.
Storage and handling
- Store in shade on flat, stone-free supports.
- Keep socket ends clean and capped until use.
- Carry pipes rather than dragging them; deep scratches weaken the wall.
uPVC mistakes
- uPVC on hot-water lines.
- Pipes buried straight into rocky or debris backfill.
- Thin low-class pipe on a pump delivery line.
- Exposed uPVC on the terrace without paint or sleeves.
- Joining inch and metric sizes without proper adaptors.