If you are replacing pipe or adding to a farm water system, the first question is not "what millimetre size do I need?" It is: which pipe system are you working with — Green Stripe Rural or Blue Line metric? TGRM stocks both. They use different sizing conventions, different pressure ratings and different fitting systems, and treating them as interchangeable is where people get caught.
1. What's the difference between rural poly and Blue Line poly?
They are two different pipe systems, not two grades of the same pipe. Green Stripe Rural is the traditional farm water pipe — economical, rated to the 800 kPa rural class, sized in inches. Blue Line is metric PE pressure pipe — the drinking-water-certified, mains-pressure family, sized in millimetres with PN pressure ratings like PN12.5. Different sizes, different ratings, different fittings.
Rule of thumb: green stripe = farm water pipe; blue stripe = drinking-water and mains-pressure pipe.
2. Which pipe do I have?
Look for the stripe first — green for rural, blue for metric. The size marking is the second giveaway: rural pipe is sold in inch sizes (3/4", 1", 1 1/4", 1 1/2", 2") and uses the rural ID-based system, while Blue Line is sold in millimetre sizes (25, 32, 40, 50 mm) based on metric outside diameter. That is why a 25 mm metric pipe and a 1-inch rural pipe are not the same pipe.
If you're repairing an old line and still aren't sure, bring a short offcut or the old fitting into the store — we can match the system on the counter.
Rule of thumb: stripe colour tells you the family; inches means rural, millimetres means metric.
3. What is Blue Line poly used for?
Drinking water and pressure. Blue Line is the family used for household and town-water connections, pressurised mains and higher-pressure pump systems. On farms it earns its place as the trunk line from a pressure pump, the line to the house, or anywhere potable-water certification or a higher pressure class is part of the job.
Rule of thumb: if the water is for the house, or the line runs at mains-type pressure — Blue Line.
4. What is Green Stripe Rural used for?
Green Stripe is the economical default for ordinary farm-water work: stock water, tank-to-trough runs, transfer lines and general farm plumbing where the pressure sits inside the rural pipe rating. It is also the natural match when you're repairing or extending a system already built on rural fittings.
Rule of thumb: existing rural fittings and ordinary farm water — start with Green Stripe Rural.
5. Will my fittings fit both pipes?
No — not as a straight swap. Rural compression fittings are made for the rural pipe system; metric fittings are made around metric outside diameters. Some specialist/adaptor fittings can bridge systems, but a standard rural fitting and a standard metric fitting should not be treated as interchangeable just because the nominal numbers look similar. TGRM stocks both fitting families in the Fittings & Valves range.
Rule of thumb: match the fitting to the pipe family, not the number on the shelf ticket.
6. Above ground and rough country
Both families can be used above ground when the product and installation are suitable. The important difference for this decision is pressure class and wall section. As practical TGRM guidance, where pipe will be exposed on sharp rock, knocked around, or laid where it cannot be bedded and protected well, we prefer the greater wall/pressure margin of an appropriate Blue Line class. That is a counter recommendation, not a claim that Green Stripe cannot be installed above ground.
Rule of thumb: protected run in friendly ground — Green Stripe is the economical starting point; exposed run over sharp rock or rough country — compare Blue Line. This is a guide only and the actual class still has to suit the pressure and installation.
7. What size pipe do I need?
This is the hardest question, and there is no responsible one-size-fits-all rule such as "25 mm for under 200 m." The right diameter depends on required flow, run length, elevation change and available pressure.
For stock water, start from what the animals actually drink. Queensland FutureBeef guidance puts beef cattle at about 45 litres a head per day on average with peaks around 60 litres, and heat can lift requirements sharply; lactating cattle can need more again.
For a mob of 100 head, 60 litres a head is 6,000 litres in a peak-demand day. The practical problem is that trough demand is not always spread evenly across 24 hours. Where watering points are few and mobs are large, size the system around the refill rate needed during the busiest watering period, not merely the daily total. That is TGRM practical guidance; final hydraulic sizing still depends on the actual run, pressure, elevation and trough arrangement. For the wider system, see our guide to setting up a water system for cattle.
Rule of thumb: size stock-water lines for the hottest day and the biggest mob at the fewest watering points — not the yearly average. A guide only.
8. TGRM poly and fittings
TGRM carries Green Stripe Rural pipe, Blue Line metric PE pipe and matching fitting ranges in store at Gympie. Stocked sizes and coil lengths change, so check the current Poly Pipe and Fittings & Valves ranges or ask — if your job needs a size or fitting that isn't racked, ask us about the wider supply range.
This is a product-selection guide only. New-system hydraulic design, pump sizing, guaranteed flow/pressure outcomes and installation engineering should be checked against the actual system requirements.
Sources referenced: RX Plastics / RX RIMS product and PE100 pipe information; PLASSON Australia poly pipeline guidance; FutureBeef (Queensland DAF) livestock water requirements. Pressure classes and stocked sizes are quoted as at August 2026 — check current product pages or the label for the rating that applies to the pipe you buy. All rules of thumb above are TGRM guidance and a guide only.
