Thanks for reply, unless my understanding is incorrect I think the rat flaps have effectively negated a break in the pipe because even if there is one, the rats are trapped on the sewer side now so cannot access any existing holes.
Hello I am posting here because I am at my wit's end, I am speculating that this is a possible plumbing issue but I acknowledge this might be the wrong forum if it's not.
I moved into my three bed semi about 5 years ago. It was built in 2007-2008, so barely 10 years old.
When I first moved in...