IS 4985:2021 is the Indian Standard (BIS) for unplasticized pvc (upvc) pipes for potable water supplies - specification. This standard specifies the requirements for unplasticized polyvinyl chloride (uPVC) pipes intended for carrying potable water. It covers the material composition (mandating lead-free stabilizers), dimensions, physical and mechanical properties, and testing methods for pipes of various pressure classes.
Specifies requirements for uPVC pipes intended for conveying potable water under pressure.
Key values for uPVC pipes including pressure classes, material properties, dimensional tolerances, and test acceptance criteria for potable water supply.
| Reference | Value | Clause |
|---|---|---|
| Pressure Rating Classes— Corresponds to Classes 1, 2, 3, 4, 5, 6, and 7 respectively. | 2.5, 4, 6, 8, 10, 12.5, 15 kgf/cm² | Cl. 6.2 |
| Working Pressure De-rating Factor (at 45°C)— Multiply class pressure rating by this factor for service at 45°C. | 0.5 | Annex C |
| Min Vicat Softening Temperature— Indicates thermal stability of the pipe material. | ≥ 80 °C | Cl. 10.8 (Table 4) |
| Max Reversion (Longitudinal)— Test at 150°C to check for residual manufacturing stresses. | ≤ 5 % | Cl. 10.3 (Table 4) |
| Impact Strength Failure Rate (TIR)— Tested at 0°C using the round-the-clock method. | ≤ 10 % | Cl. 10.4 (Table 4) |
| Density of Pipe Material | 1.40 - 1.56 g/cm³ | Cl. 10.6 (Table 4) |
| Max Lead (Pb) Content in Material— Strictly for pipes intended for potable water supplies. | ≤ 0.2 % by mass | Cl. 4.1.1 |
| Max Overall Migration Limit— Ensures safety for contact with potable water as per IS 9845. | ≤ 60 mg/l | Cl. 10.10 (Table 4) |
| Max Specific Migration of Lead (Pb)— Specific limit for lead leaching into potable water. | ≤ 0.01 mg/l | Cl. 10.10 (Table 4) |
| Acceptance Hydrostatic Stress (1h @ 27°C)— Short-term test to confirm pressure integrity. | Varies by class (e.g., 10.3 MPa for Class 2) | Cl. 10.9.2 (Table 6) |
| Type Test Hydrostatic Stress (1000h @ 60°C)— Long-term test to validate material performance under stress. | Varies by class (e.g., 4.1 MPa for Class 2) | Cl. 10.9.1 (Table 5) |
| Tolerance on Wall Thickness (e)— No negative tolerance is permitted on wall thickness. | + (0.2 + 0.1e) mm, - 0 mm | Cl. 6.3.2 |
| Tolerance on Mean Outside Diameter (e.g., DN 110)— No negative tolerance is permitted on mean OD. | + 0.4 mm | Table 1 |
| Standard Pipe Length (Effective)— Other lengths, such as 3m, may be supplied by agreement. | 6 m | Cl. 6.5 |
| Min Socket Length (Solvent Cement)— Minimum length for a solvent cement type socket. | 0.5 DN + 6 mm | Cl. 6.4.2.1 |
| Opacity Requirement— Pipe must be opaque to prevent algae growth. | ≤ 0.2 % light transmission | Cl. 10.2 (Table 4) |
| Resistance to Sulphuric Acid (Mass Change)— Test requirement after immersion in H₂SO₄. | ± 0.25 mg/mm² | Cl. 10.7 (Table 4) |
| Max Sulphated Ash Content— Limits the amount of inorganic filler in the uPVC compound. | ≤ 5 % by mass | Cl. 10.5 (Table 4) |
| Standard Pipe Colour— Other colours may be used by agreement between purchaser and manufacturer. | Dark Grey | Cl. 5.2 |
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
IS 4985 is the specification for unplasticized PVC (uPVC / PVC-U) pipes for potable water supply. It governs cold-water supply piping (≤ 45 °C continuous service) for buildings, distribution networks, agriculture, and rising mains.
This is the standard your plumbing BOQ cites when calling for buried/exposed water pipes from 20 mm to 630 mm diameter, in pressure classes (PN) from 2.5 to 16 bar.
Use IS 4985 pipe when: - Building plumbing (cold water rising mains, branch piping) - Underground water mains in housing colonies - Agricultural irrigation rising mains - Tubewell delivery lines (not the column pipe — that's IS 12818 uPVC casing/screen) - Industrial water lines (cold, non-aggressive fluids)
Don't use IS 4985 uPVC for: - Hot water (> 45 °C continuous) — use IS 15778:2023 CPVC instead - Drain / waste / vent (DWV) — use IS 13592:2013 PVC-U pipes (different formulation, lower pressure) - Sewer / drainage with chemical exposure — check chemistry compatibility - Above-ground exposed pipes in direct sunlight without UV protection (uPVC degrades; specify carbon-black-stabilised grade or paint over)
The 2021 revision is the current authority and replaces the older 1988 / 2000 versions; check that supplier datasheets cite IS 4985:2021.
Pressure ratings (PN at 27 °C continuous service):
| Class | Pressure rating | Typical use | |---|---|---| | 2.5 (PN 2.5) | 0.25 MPa = 2.5 bar | Low-pressure distribution, short rises | | 4 (PN 4) | 0.4 MPa = 4 bar | General building cold water | | 6 (PN 6) | 0.6 MPa = 6 bar | Building risers up to 5 floors | | 10 (PN 10) | 1.0 MPa = 10 bar | High-rise risers, mains | | 16 (PN 16) | 1.6 MPa = 16 bar | Booster mains, industrial |
Outside diameter range: 20 mm to 630 mm in standard ISO series (20, 25, 32, 40, 50, 63, 75, 90, 110, 125, 140, 160, 180, 200, 225, 250, 280, 315, 355, 400, 450, 500, 560, 630 mm).
Wall thickness is determined by OD × pressure class via the standard SDR (standard dimension ratio) table. Higher pressure class = thicker wall = lower SDR.
De-rating for elevated temperature: rated pressure × derating factor: - 27 °C: 1.0 (rated) - 35 °C: 0.85 - 45 °C: 0.65 - > 45 °C: do not use (move to CPVC per IS 15778)
Standard pipe length: 6 m (effective length excluding socket); 3 m and 4 m also produced.
Hydrostatic pressure test (key acceptance): - Short-term (1 hour at 27 °C): hoop stress 30 MPa — pipe must not burst - 100-hour at 27 °C: hoop stress 25 MPa — pipe must not burst or visibly bulge - 1000-hour at 27 °C: hoop stress 20 MPa — confirms long-term performance
Vicat softening temperature: ≥ 80 °C (this is what limits hot-water use; CPVC has VST ≥ 110 °C).
Density: 1.40-1.46 g/cm³ (formulation marker — outliers indicate low filler or wrong polymer).
Falling-weight impact test (drop test): at 0 °C, must not crack at specified drop height (size-dependent, 200-2000 g hammer).
Reversion test: length change ≤ 5 % when heated to 150 °C for prescribed time (residual stress check).
Lead and heavy-metal limits: since IS 4985:2021 is a *potable water* standard: - Lead: ≤ 0.3 mg/L migration (24-hour water immersion) - Cadmium: ≤ 0.1 mg/L - Other heavy metals per BIS Annex C
Resistance to internal pressure at 60 °C: sustained for 1 hour at hoop stress 12.5 MPa — proves short-term tolerance to warm water.
Marking on pipe (visible at any 1 m length): - IS 4985, year of revision - Manufacturer name / trademark - Nominal OD × wall thickness × pressure class (e.g., `110 × 4.2 × PN 6`) - Production batch and date - BIS licence number (the ISI mark)
1. Specifying uPVC for hot water. uPVC's Vicat softening is 80 °C — continuous hot water (geyser supply, solar hot loops) sags and creeps the pipe. Use CPVC IS 15778 for any hot side. 2. No pressure class on the BOQ. 'IS 4985 uPVC pipe 110 mm' is incomplete — class can be PN 4, 6, 10, or 16, with very different wall thickness and cost. Always specify class. 3. Buried pipe without bedding sand. uPVC needs 75-150 mm sand bedding around the pipe; rigid boulder backfill creates point loads that crack the wall over time. See IS 7634 Part 2. 4. Solvent cementing without proper joint preparation. Surfaces must be dry, deburred, and primed (purple primer) before solvent cement; rushed joints fail at 1-2 bar. Joint cure time before pressurising: minimum 1 hour for cold; 24 hours for full strength. 5. UV exposure on overhead piping. Standard uPVC is not UV-stabilised; 6-12 months of direct sun causes brittleness and surface chalking. Specify UV-stabilised grade or paint with two coats of acrylic (Reaffirm with supplier). 6. Mismatched fittings. Some 'compatible' fittings are made to different OD tolerance series (DN inch vs DN mm); leak-prone joints. Source pipes and fittings from the same manufacturer / certification. 7. Hydro-testing pipes immediately after solvent cementing. Pressurise after the joint cement has cured per supplier datasheet; hydro-testing too early splits joints. Standard cure window: 1 hr at 0.5 bar, 24 hr at full pressure rating. 8. Ignoring pressure surge. Water hammer in long uPVC mains can momentarily exceed 2× the static rating. Specify air valves, surge arrestors, and slow-closing valves on long runs.
1. Fixture demand calculation (CPHEEO tables) — domestic load units, peak flow. 2. Pipe sizing (Hazen-Williams or Darcy-Weisbach) — friction loss, residual pressure target. 3. Material selection by service: - Cold rising main + branches: IS 4985 uPVC PN 6-10 - Hot water side: IS 15778 CPVC - Soil and waste vertical stack: IS 13592 uPVC - Underground water main outside building: IS 4985 uPVC PN 10 with bedding sand and warning tape, OR DI/HDPE for diameters > 200 mm 4. Pressure class selection — peak working pressure × 1.25 safety + de-rating for ambient temperature 5. BOQ language: `uPVC pipe per IS 4985:2021, ISI marked, 110 mm OD, PN 6 (working pressure 6 bar), 6 m length with solvent-welded socket, supplier-recommended primer and solvent cement; lead-free formulation per IS 4985:2021 Annex C.` 6. Site QA: ISI mark visual check on every length; random hydro-test on assembled joints before backfilling; supplier batch test certificate filed.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Reference Temperature for PN Rating | 27°C | 20°C | ISO 1452-1 |
| Design Stress Basis (for MRS 25 MPa material) | 8.6 MPa at 27°C | 10 MPa at 20°C (with safety coefficient C=1.25) | ISO 1452-1 |
| Vicat Softening Temperature (Min.) | ≥ 79 °C | ≥ 79 °C | ISO 1452-1 |
| Longitudinal Reversion (Max.) | ≤ 5 % | ≤ 5 % | ISO 1452-2 |
| Opacity Test Requirement | No visible light transmission | < 0.2% light transmission | ISO 1452-2 / ISO 7686 |
| Impact Strength (TIR at 0°C) | TIR ≤ 10% | TIR ≤ 10% | ISO 1452-2 |
| Specified Colours for Potable Water | Dark Grey, Light Grey, or Cream | Grey or Blue (Blue often preferred/mandated) | ISO 1452-2 |