Question and photo say it all really. There is a gully trap for the grey wastewater at the back of our multi-unit building that is about 120 years old. The trap seems to be made of fired clay and has a large crack.
Is this going to be a significant problem, and can it be repaired without needing to excavate the concrete and replace the whole thing? I was thinking using a flexible waterproof sealant to fill the crack.
(I am in New Zealand).