A manhole, or inspection chamber, is an access point to an underground drainage system. It allows the drains to be cleaned, cleared and inspected when required.
These chambers are typically installed:
a) where a branch pipe joins a main drainage run in the system
b) when there is a straight run of piping over 22-metres long, or
c) when a drain changes direction horizontally by more than 30 degrees.
Manhole covers are used for safety and also to stop people entering without authorisation. Older manholes may contain steps for easy man access, but modern smaller, plastic inspection chambers are designed so that physical entry is not required. Where access is required, ‘confined space’ risk assessments and method statements must be prepared.
Manhole and inspection chamber guidance is governed by Building Regulations.