HDPE Pipe Color Code: What It Means, Region by Region

There is no global HDPE colour code. Across the documents below, blue means potable water in North America, a shade graded to the PE grade in the UK, and only one of two acceptable drinking-water markings in Australia, where plain black is equally correct. Colour is set by the specification the destination accepts; pipe marked to the wrong document is rejected on site.

Black Is the Material, Not the Message

Black is a specified quantity. UK Water Industry Specification WIS 4-32-19 sets carbon black at 2 per cent to 2.5 per cent measured to ISO 6964, with a primary particle size of 10 nm to 25 nm. That loading is the ultraviolet protection, and why pressure pipe starts black. Our complete guide to HDPE pipe covers the material.

Identification goes on top, as stripes or as a jacket: a continuous coloured outer layer co-extruded into the pipe wall, in the wording of the Australian commentary on AS/NZS 4130. A solid pipe and a striped pipe can carry identical duty, so the question is whose scheme is on it.

North America: One Code, and It Stops at the Building Line

Plastics Pipe Institute Statement V, reviewed April 2017, follows the American Public Works Association Uniform Color Code. That code assigns colour by service: red electric power, orange telecom and signal lines, yellow fuel gas and petroleum, green sewers, blue potable water, purple reclaimed water.

It also states a limit most summaries drop: the code “is only intended for solid wall pipe used outside of buildings”, not corrugated pipe and not pipe indoors. The gas rule is narrower than it reads. ASTM D2513, F2785 and F2945 do not require gas pipe to be yellow, only that any identifying colour be yellow. ASTM D3035, F714, F2160 and NEMA TC7 forbid yellow on theirs.

United Kingdom: Blue Is Graded, Brown Means Barrier, Yellow Means Gas

WIS 4-32-19, Issue 3 of November 2011, fixes the potable-water colour to the PE grade: light blue for PE 80 within BS 5252 range 18E51 to 18E53, dark blue for PE 100 within 20D44 to 20D45 or 20E53 to 20E56. Stripe count is specified too: four stripes up to 180 mm, eight above it.

The stripes on that pipe are brown, and brown is not a service here. Scottish Water’s guidance says external brown stripes identify a multi-layer pipe built for contaminated ground. Gas is a separate rulebook. Street Works UK Volume 1, Issue 9 lists buried gas PE as yellow, or yellow over a removable brown-striped skin, up to 2 bar, then orange to 7 bar. The product specification GIS/PL2-2:2022 puts the same yellow in clause 6.2, but it is access-restricted: confirm the wording with the network operator. The water side sits on BS EN 12201-1 and its UK National Annex.

Australia and New Zealand: The Same Two Services, a Different Palette

Table 4.1 of the WSA Water Supply Code of Australia gives PE reticulation mains as plain black or black with blue stripes for drinking water, and plain purple or black with purple stripes for non-drinking water. Plain black is therefore a correct potable marking there, which a North American reading would call unmarked stock. The industry commentary on AS/NZS 4130 names the recycled-water colour lilac and pins the shades to RAL numbers. The same table forbids sleeving purple over a blue pipe, or the reverse.

The Table That Says Colour Equals Pressure Class Is Not a Standard

One chart circulates widely: yellow for PN 4, red for PN 6, blue for PN 10, green for PN 16. On 18 September 2026 it sat at ranks four and seven of the US results for this query, and it is in none of the documents above. ISO 4427-1:2019, published August 2019 and 17 pages, is titled Part 1: General. Ask for blue expecting PN 10 and you get a potable marking at whatever class the line ran. Pressure class comes from the SDR, covered in our size and SDR guide. The ISO 4427-2 and EN 12201-2 colour clauses are paywalled and are not quoted here.

Writing the Colour Line on a Purchase Order

Table 1 — HDPE and PE pipe markings by governing document, region and service

Marking on the pipe	Governing document and where it applies	What it means there	Verdict if read under another system
Solid blue, or blue stripes	PPI Statement V and APWA code; North America, buried, outside buildings	Potable water	Inside a building, or on profile pipe, this code does not apply
Solid yellow, or yellow stripes	PPI Statement V and APWA code; North America	Fuel gas, oil, petroleum, steam	Assuming ASTM mandates yellow; it reserves the colour instead
Purple or lavender	PPI Statement V and APWA code; North America	Reclaimed water, irrigation, slurry	Reading purple as a material grade or pressure marking
Light blue PE 80 or dark blue PE 100, brown stripes	WIS 4-32-19 Issue 3; United Kingdom potable water	Barrier pipe for contaminated ground	Reading brown as a service colour rather than pipe construction
Yellow, or yellow over a removable brown-striped skin	Street Works UK Vol 1 Iss. 9; UK buried gas up to 2 bar	Buried gas main or service; orange above 2 bar	Buying to a water specification for a gas network
Plain black, or black with blue stripes	WSA 03 Table 4.1; Australia and New Zealand	Drinking-water reticulation main	Rejecting plain black as unmarked or non-potable stock
Plain purple, or black with purple stripes	WSA 03 Table 4.1; Australia and New Zealand	Recycled, non-drinking water	Sleeving purple over blue pipe, which the same table forbids
Any colour read as a PN pressure class	No document cited on this page	Nothing; a factory convention	Ordering a pressure class by asking for a colour

Source: PPI Statement V (2017); WIS 4-32-19 Iss. 3 (2011); Street Works UK Vol 1 Iss. 9 (2018) Table 1; WSA 03 Table 4.1; PIPA TC4130.

Five lines make a colour instruction enforceable:

• the governing document and its edition, written out in full;
• the country or utility that will accept the delivery;
• the service the line will carry;
• the marking method: solid colour, stripes, or a co-extruded jacket;
• the shade reference and stripe count where the document gives them, as WIS 4-32-19 does at four stripes below 180 mm and eight above.

Where a destination has no national rule, the utility or tender specification governs; get it in writing. Grade, SDR and standard are separate order lines, in our standards guide and on our product pages.

Conclusion

The expensive mistake is assuming the chart you read governs where the container lands. Pipe bought to the North American code can fail a UK inspection on stripe count alone at 180 mm. Name the document, not the colour.

Frequently Asked Questions