Sanitary manhole

A sanitary manhole (sewer manhole, sanitary sewer manhole or sewer maintenance hole) is a manhole that is used as an access point for maintenance and inspection of an underground sanitary sewer system. Sanitary manholes are sometimes used as vents to prevent the buildup of pressurized sewage gas. Additionally, they are used for debris removal, and application of chemicals such as degreaser and insecticide.

When underground sewer lines are laid close to the ground level (this may be at the depths of less than 0.75 metres (2.5 ft) or 2 metres (6.6 ft) depending on local regulations), an inspection chamber is used as an access point instead. Inspection chambers allow access to sewer lines without requiring a person to get in them.