Once the water has been through the treatment process, it is transported along the drinking water network to your home (it can be imagined as a city transport network).

The network begins at the treatment plant, where water is transported along bulk mains – they are similar to a state highway which carries the bulk of the water into the city. They are usually larger than 375mm and can be as big as 1400mm in diameter.

The bulk mains then lead to reservoirs. Reservoirs are storage tanks that store water in the network. They are used to:

- provide direct supply and set operating pressure within the downstream local water distribution network;
- meet the supply zone’s peak water demand as the bulk water supply pipeline cannot meet peak demand without supplementary from the reservoirs;
- provide sufficient storage for firefighting;
- reduce the risk of disruption to the bulk supply or treatment plant causing loss of supply to customers; and
- retain water following significant seismic events.

Off the reservoirs are trunk mains - these are similar to the ‘main roads’ around your city. They are usually 250-600mm in diameter. These trunk mains may also lead to smaller reservoirs.

The trunk mains then connect to smaller pipes called reticulation mains - these pipes are the ‘suburbs’ (the groves, crescents, streets etc.) in the network. They are usually 50mm to 200mm in diameter.

Finally, there are the private laterals. They are the ‘driveways’ in the network. They connect the public drinking water network with your home plumbing system. These pipes are very small, typically 20-32mm in diameter. If damage happens to these pipes (on the home owners side of the manifold/isolation valve/toby), it is the responsibility of the home owner to repair them.

At certain points along the network there are also the following:

Maintenance chambers/man-holes – these chambers are used by network operators as access points along the network (house valves, flowmeters or pressure reducing valves) to make quick repairs.

Pump stations - There are also 83 pump stations around the network. These pump stations are located at points in the network where drinking water needs to be pumped (usually up a hill).


Backflow is the unintended and undesirable reverse flow of water or other liquids within the plumbing system of a property to the public mains supply.Backflow may be caused by back pressure, back siphonage or a combination of both.It can result in contaminants being drawn into the public drinking water system through a cross connection[/your-water/stormwater/looking-after-your-stormwater/the-case-against-cross-connections/].   Read more

Supply connection contractors

Only approved contractors[/contractors/] can be used to put new connections in place, and we will check the connection once it's done to ensure it meets council standards.It is the responsibility of the applicant to commission the contractor (at agreed terms) to carry out this work.   Read more