Water mains have several appurtenances, located in chambers, which require preventive maintenance. A chamber is an underground room or vault accessible from street level by means of covered surface maintenance hole openings. In the past, chambers were usually constructed of brick masonry or reinforced concrete. Currently, we are using circular precast concrete sections in most cases. These are used to isolate sections of the main as required for operation or maintenance.
Branches are the connections through which water is supplied to the community areas.
The branch valves are part of the mains and are usually gate valves ranging in size from 400 to 600 mm. They are used to isolate supply to the community areas' systems, when required, for repair or maintenance to either the local or municipal main. The 100 mm double acting air valves used in our system are located at all high points in a main to allow continuous release of the small quantities of air trapped in the water. They also permit the entry of large volumes of air, when necessary, to prevent collapse of the pipe under pump failure conditions, where a vacuum is established inside the main. Air valves are often mounted on the access maintenance hole cover in a chamber.