Brisbane has turned its back on the federal Labor government's national broadband network (NBN), announcing it would go it alone and build its own network within four years.

The fibre optic network will be installed in the city's wastewater network and sewer pipes from next year.

Brisbane Lord Mayor Campbell Newman at his Brisbane office.

It's expected that about 15,000 homes per month would receive access to the network once the rollout begins.

Lord Mayor Campbell Newman, from the Liberal National Party, said he "was not prepared to wait" for the federal Labor government's network to be built in Brisbane.