Just been out and checked down the manhole again this morning - no flow from my house is reaching the manhole so phoned Thames Water up and reported the blockage before it backs up to my house. I can see that this is going to be a daily event from now on until the repair or replacement is carried out and I don’t think I’ll even need to bother checking the flow in future. It’s clear to me that water can flow through the
blister but the first solid that reaches it can’t get through and then the blockage occurs. If it was just us, we could use our downstairs loo with the macerator but unfortunately we share the drain with a family of 5 who don’t have a macerator.