The Wavin Osma range of chambers offers a number of base and shaft configurations to gain access to underground drainage pipelines, giving Specifiers and Installers the freedom to choose the most suitable system for their needs. The Wavin Osma Inspection Chambers comply where applicable with the requirements of the following British Standards: BS EN 13598 Parts 1 & 2 Plastics piping systems for non pressure underground drainage and sewerage & BS 7158:2001 Plastic inspection chambers for drains and sewers – Specification.