Hi there! Hope someone can help. We love in a semi and the non adjoining house has had some new drain pipes fitted for 2 bathrooms and a new kitchen. They have dug up their path and joined their sewage pipe to ours instead of digging up their front path and joining to the main sewage pipe under the pavement. They didn't ask our permission and if anything leaked at their house and backs up into our house who is liable for damages? And do they need our permission? Thanks