Air test (drain)

An air test pressurises a sealed section of new or repaired drainage with a low controlled volume of compressed air, allowing engineers to monitor pressure loss against the acceptance criteria set out in BS EN 1610. Compared with a water test, the method avoids the need to introduce significant volumes of water into the line and is widely used on new build, adoption and refurbishment projects across London. Pressure is typically increased to around 100mm water gauge, with permissible loss limits depending on pipe diameter and length. Engineers carry out the test in accordance with industry practice using calibrated gauges and an inflatable stopper at each end. A clear written record supports sign-off under Building Regulations Part H and any subsequent adoption agreement with Thames Water under Sewers for Adoption.