Householders are responsible for their private drains. These are the pipes that carry foul water from just one property. Where the pipe meets another pipe from another property or goes beyond the boundary of a property it becomes a sewer and the responsibility of Southern Water.
If you have a blocked sewer you should contact Southern Water
A cesspit is a sealed storage tank which holds sewage from a property. The sewage is not treated in this tank. Older cesspits are constructed of brick or concrete. Modern ones are made from fibreglass, steel or polyethylene. Cesspits need regular emptying every four to six weeks by a tanker.
A septic tank provides some basic treatment of domestic sewage. The solids settle and the overflow liquid goes underground into a drainage field. This allows the ground to further treat the sewage. Solids that build up at the bottom of the tank should be pumped out about once a year.
Cesspits and septic tanks must be emptied regularly and it is an offence to allow them to overflow.