Choosing the right poly pipe size is one of the most common questions our team gets at TGRM. Undersizing causes pressure loss, slow trough fill times, and animal water stress. Oversizing wastes money. Here's how to get it right.
Pressure Ratings
Rural poly pipe comes in two main pressure ratings:
- PN12.5: Suitable for gravity-fed systems and low-pressure pumped systems. Most common for farm water.
- PN16: Suitable for higher-pressure pumped systems and longer runs. Use when pumping from a bore or over significant elevation changes.
Diameter Selection
Pipe diameter determines how much water can flow per hour. As a practical guide:
- 25mm: Short runs under 200m supplying 1–2 troughs.
- 32mm: Medium runs 200–400m, 2–4 troughs.
- 50mm: Long runs over 400m, multiple troughs, or where significant flow is needed.
- 63mm+: Main supply lines from bore or dam to header tanks.
Rule of thumb: when in doubt, go one size up.
Fittings
Use compression fittings (Plasson or equivalent) for most farm applications — no glue, no special tools, easy to repair in the paddock. Browse our Fittings & Valves range.
Shop Poly Pipe at TGRM
TGRM stocks PN12.5 and PN16 poly pipe in 25mm, 32mm, 50mm, and 63mm diameters, plus a full range of Plasson fittings, ball valves, cocky valves, and float balls. Browse our Poly Pipe and Water Troughs collections. Cut to length available in-store. Delivered Australia-wide from Gympie QLD.
Related reading: Setting Up a Water System for Cattle | Common Q&A for Queensland Farmers