From 1 October 2011, Southern Water Services took over responsibility for private shared sewers and they became part of the public sewer network (with the exception of private pumping stations and associated rising mains which will not transfer until October 2016). This was done across the whole country. Before this, shared sewers were private and were the responsibility of householders who connected to them. When things went wrong, the householder had to pay for repairs. Since the transfer, householders are only responsible for the section of pipe that serves their property alone and lies within their boundary. If you have insurance to cover your drains and sewers we do not recommend that you cancel it as you may need it in the future if anything goes wrong with the section of pipe that remains your responsibility. Repairs to sewers and drains can be extremely expensive.
There are some exceptions including septic tanks and cess pits. You can see more on the Southern Water Services website: www.southernwater.co.uk/help-advice/sewers
If you have problems with your shared sewer, contact Southern Water Services on 0330 303 0368.