Understanding the 4th Edition Gravity Pipe Inspection Manual
A quick guide to why standards-aligned condition coding matters — and how DIS applies the 4th Edition manual to every inspection we deliver.
If you've received a pipe condition report before, you may have seen defect codes and structural / service grades. But what sits behind them?
The 4th Edition Gravity Pipe Inspection Manual is New Zealand's recognised standard for coding and grading the condition of gravity pipe networks. It provides a consistent language for describing everything from cracks and fractures to root intrusion, displaced joints and infiltration — so that two different operators, on two different days, describe the same defect the same way.
At DIS, every survey we deliver is coded to this standard. That consistency is what makes a condition report defensible: asset owners can compare pipes, track deterioration over time, and justify renewal decisions with confidence.
Want to know more about how we report? Get in touch with the DIS team — we're always happy to walk clients through a sample report.