Myself and the others in my row of six cottages have been having a bit of agro with blocked drains and sewers lately
Just found out this morning that if more than one dwelling share a sewer/drain and were built before 1937 that the local sewerage supplier are responsibly
These are known as public sewers and in my case its Anglian Water's responsibility. Here now rodding and hosing so must be true, they tend not to publicise that too much.
Suppose it could be hard to prove exactly when your house was connected to the main sewer if it was bult very near the cut-off date, ok for us as they were built in the 1890's
Another good reason to buy an old house along with them being built properly and as a rule having decent sized gardens too.