A home's plumbing is the most invisible thing in it. It is also the most unforgiving. Get it wrong, and the only time you will find out is the morning a joint fails and the ceiling starts staining below it.
Two plastic pipes dominate modern Indian plumbing: CPVC and UPVC. Most homeowners, and a surprising number of contractors, treat them as interchangeable. They are not.
The short version
- CPVC (Chlorinated Polyvinyl Chloride) — handles hot and cold water. Rated for continuous service up to around 95°C. Use it for every hot water line, and as the default for all indoor water supply in a modern home.
- UPVC (Unplasticised PVC) — cold water only. Cannot handle hot water. Use it for cold-only supply in specific applications and for underground water mains where CPVC would be overkill.
- SWR (Soil, Waste and Rainwater) — a separate PVC system for drainage. Non-pressurised, larger diameters, different jointing. Every home needs it; it is not the same as CPVC or UPVC.
Where the spec actually goes wrong
In our work across Ambala, Chandigarh, Panchkula, Kurukshetra and the wider region, the three recurring failures are:
1. One pipe for everything. A site team uses UPVC because it is cheaper, including on the hot line. Within a year, the joint at the geyser outlet starts weeping.
2. Undersized risers. A 15mm CPVC riser feeding three bathrooms on the first floor cannot hold pressure once more than one outlet opens. Rain showers disappoint; mixers hunt for temperature.
3. Mismatched solvent cement. CPVC and UPVC use different solvent cements. Using UPVC cement on CPVC joints is a slow-motion failure — the joint looks right on day one and fails six months later.
How we write the pipe schedule
At HCS Home, when a project comes through our studio in Ambala, we do the pipe specification line-by-line, by floor. Astral is our primary pipe partner; Rhinox handles composite and specialist runs.
For a typical three-bathroom home:
- Main inlet (ground level to underground tank): UPVC, 32mm or 40mm depending on incoming pressure.
- Tank to overhead system: UPVC, 25mm.
- Overhead tank to floor risers: CPVC, 25mm minimum; larger if the pump is boosted.
- Floor distribution to each bathroom: CPVC, 20mm.
- Final connection to each fitting: CPVC, 15mm — but only if you are certain about fitting flow rates. For rain showers and multi-jet panels, 20mm is the honest choice.
- Drainage (every line): SWR, with solvent-weld joints on concealed runs and ring-fit joints where accessibility matters.
Why it matters beyond pipes
Plumbing is not a standalone decision. A 300mm rain shower needs 2–3 bar at the outlet. If your CPVC sizing assumes 15mm throughout, a booster pump from our Water Solutions vertical (Grundfos or Ebara) is going in whether you planned for it or not. Better to size the pipes correctly on day one.
This is the conversation architects and homeowners have with us before the floor goes down — not after the tiling is done.
What to ask your contractor
Before any concealed plumbing goes into the wall, ask three questions:
- Is every hot line CPVC? Not "most of it." Every metre.
- What is the riser diameter? If the answer is "standard," ask for millimetres.
- Which solvent cement are you using? The answer should differ for CPVC and UPVC joints.
If the answers are uncertain, come to us before you close the walls. Pipes behind a tiled wall are the last thing you want to discover a problem with.