Which Pipe for a Geyser: CPVC, Not uPVC, and How to Connect It
Plumbing Guides
Which Pipe for a Geyser: CPVC, Not uPVC, and How to Connect It
3 min read
Quick answer: Use CPVC SDR 11 for both the cold inlet and the hot outlet of a geyser, and never uPVC or PVC. uPVC is rated to 45°C by its makers and a domestic geyser is normally set between 55°C and 65°C. Ashirvad's CPVC manual also says not to join CPVC directly to a water heater outlet: fit a metal section first. A 5 metre length of 3/4 inch CPVC SDR 11 is ₹435 with us (list ₹870), before GST, on 15 November 2026.
The geyser itself rarely causes the leak. The pipe next to it does, and it is nearly always one of three things: the wrong plastic, a plastic thread on a hot joint, or CPVC screwed straight onto the heater.
Why not uPVC
| uPVC | CPVC | |
|---|---|---|
| Maximum recommended service temperature | 45°C | 93°C |
| Pressure rating at 82°C (SDR 11) | Not rated | 7.0 kg per sq cm |
| Use on a geyser line | No | Yes |
The figures are from the Astral uPVC and Astral CPVC PRO catalogues. uPVC on a hot line softens and sags rather than bursting, so it can run for a year before the joints give. The rest of the comparison is in CPVC vs uPVC.
The inlet matters too
People fit CPVC on the hot outlet and leave the cold inlet in uPVC because it "only carries cold water". When the geyser heats, hot water can back up a short way into the inlet. Run CPVC for at least the last stretch to the geyser on both sides.
How to connect it
- Metal at the heater. The Ashirvad CPVC manual says it is not recommended to connect CPVC pipes directly to the water heater outlet, and asks for a metal nipple at the heater so the CPVC is kept away from the heat there. In practice that is the pair of braided steel connection hoses, or a short GI or brass nipple.
- Brass thread, not plastic thread. Where the metal meets the CPVC, use a brass threaded adaptor. Plastic threaded adaptors are for cold connections.
- A valve on the inlet. A ball valve on the cold inlet lets the geyser be isolated for service without shutting the bathroom.
- SDR 11 on the hot side. The thicker class has the higher rating at temperature.
- Let the joints cure before filling. Times are in how to use CPVC solvent cement.
From our shop
Products in this guide
Live dealer prices. Add to cart, or ask for a GST quote on the whole list.
What the parts cost
Our prices at Viveknagar on 15 November 2026, before GST, list price beside them.
| Part | Our price | List price |
|---|---|---|
| CPVC SDR 11 pipe, 1/2 inch, 5 m | ₹325 | ₹650 |
| CPVC SDR 11 pipe, 3/4 inch, 5 m | ₹435 | ₹870 |
| Brass threaded male adaptor (MABT), 1/2 inch | ₹150 | ₹300 |
| Brass threaded male adaptor (MABT), 3/4 inch | ₹183 | ₹365 |
| CPVC ball valve, 1/2 inch | ₹76 | ₹168 |
| CPVC elbow 90°, 1/2 inch | ₹15 | ₹29 |
| CPVC solvent cement, yellow, 118 ml | ₹158 | ₹288 |
What each fitting is called is explained in CPVC fittings names and uses.
Questions we get asked
Can I use PVC pipe for geyser water?
No. PVC and uPVC are cold water pipes. Use CPVC.
Is 1/2 inch enough for a geyser?
For a single bathroom geyser, 1/2 inch to the geyser and from it to the shower is normal. A central or large storage heater feeding several bathrooms needs a 3/4 inch hot main.
What about a solar heater?
Solar water can get hotter than geyser water because there is no thermostat. That needs more metal at the tank; see which pipe for a solar water heater.
Sources
- Ashirvad FlowGuard Plus CPVC technical manual: water heater connections, pressure ratings.
- Astral CPVC PRO catalogue and Astral Aquarius uPVC catalogue: service temperatures.