drain/gully joint leak

[JohnD]

observe also that the mortar between the bricks has been washed away. Hose out mud and pack the joints with mortar. It can be a stiff dry mix because the bricks are wet.

 

[ree]

I agree, siphonage is possible in theory - altho i never encountered it in actuality. But i wasn't even thinking that way when i suggested combining the wastes, so i accept your criticism.