Originally Posted by
Ttaskmaster
^ This.
The PO who built my current garage/workshop actually did a vaguely OK job, although he put the tacks right through the roof, resulting in some leaking.
I recently got up there and tarted up the roof with some bitumen paint and it's turned out rather nicely.
Anything post-1936 that serves one peroperty is a private drain.
Under the Public Health Act 1936 all sewers coming within the definition of a sewer under the Public Health Act 1875 and which were in existence on 1 October 1937 became public. From 1937 onwards sewers were only public if they were laid or adopted by the sewerage undertaker (or its predecessors that exercised the same function).
However.....
Under the old regs, drains (private) became sewers (public) at the point where they left the curtilage of private property, regardless of how many other drains connected into the line.
Now, (currently) from the point your drain joins (or is joined by) the drain of another single property (this defininion varying, when it comes to types of flat), it becomes a public sewer.
Your local water utilities company should have details, but pretty much any of their websites will explain it in detail - It's part of the Water Industry Act of 1991, sections 102, 104 and 105A.