In water supply and drainage, mining and municipal pressure pipeline projects, pipes are often buried deep underground and designed for a service life of up to 50 years. Faced with complex ground settlement, corrosive groundwater and sustained high-pressure surges, how is a high-density polyethylene (HDPE) pipe made to meet the required quality standards? Quality inspection is more than a collection of numerical results: it is a progressive system of technical assurance. This whitepaper explains the reasoning behind HDPE pipe quality testing and the four demanding stages of assessment that a high-quality pipe must pass.