Welsh firm H2O Networks has announced it is to provide super-fast broadband via networks laid in the sewers.

The company has shortlisted three towns to test the new fibre-optics system; Bournemouth, Northampton and Dundee. It is now in talks with the towns' councils about providing the service that can reach speeds of up to 100Mbits/sec.

H2O will probably act as a wholesaler so it is also in discussions with several internet and content groups.

The idea of providing broadband connections this way is not new. Last year Aberdeen University signed a 10-year deal with H2O.

London-based firm Geo also offers internet connections via the sewers. It serves mainly businesses but also leases its lines to consumer providers such as Tiscali and Carphone Warehouse.

Similar systems are also in use in Paris and parts of Japan.

With the Focus (Fibre Optical Cable Underground Sewer) system, the fibre is fixed into the sewer. The company claims that lying at depths of up to five metres below the ground there is no danger of rodents chewing through the cables.

The service will be delivered to individual homes via a four-inch box attached to the house.

BT has also announced it is to install its first fibre-to-the-home (FTTH) links at a huge estate being built at Ebbsfleet Valley in Kent, promising speeds of up to 100Mbits/sec.

H2O will announce the lucky town in April and will begin to install the fibre in the sewage system in the autumn. It will take at least 18 months.

However, Antony Walker, head of the UK's Broadband Stakeholder's Group, cautioned that schemes such as the H20 and BT projects can not alone create the fast broadband speeds Britain needs.