Just had a flood in my cellar (luckily nobody was detained there at this point in time). Source was a concrete 40cm square inspection hatch. Pulled it to find the foot square drain full of water not running away. Went to the next inspection hatch and pulled that. Just spent the last half an hour digging 5-6 pounds of what looks like white clay out of it. Presumably this is some sort of fat build up from the kitchen/washing machine which joins that drain? From this drain a 5 inch pipe heads out under the garden 2mtrs deep for about 30 mtrs, and comes out of a bank on the lane and into the ditch. I think there is a ground filter somewhere in between, as the water coming out into the lane is tested yearly and is OK. Toilet sewage is going via a septic before joining the ground filter also. This has happened in the 2-3 years since I last looked into that drain. How can I sort this in the longer term? Presumably there is a chunk of dislodged fat blocking the outflow which is can be sorted, but I guess my ground filter must be full of the same crud?