u/another_new_login

I have a stormwater main through my backyard. The neighbour has a connection to it. They have a blockage on their connection and are asking us to cover a share of the costs. Do we have any legal obligation for this?

We don't yet know where exactly the blockage is, if that's relevant.

Edit: Additional context. The council has checked the main and there's no blockage. The blockage is in their connection.