I moved into my 1937-built semi-detached house two years ago. I detect an intermittent smell in my front room which shares a party wall with neighbour. Outside on the boundary there is a drain originally serving a downpipe from a valley gutter between our two pitched roofs. 3 or 4 years ago the neighbour (absentee landlord with 6 student tenants) added an extension at the front with a new kitchen. The earthenware hopper now serves three pipes: original downpipe, the outlet from the kitchen and one from another new rainwater downpipe. I went out after dark and examined the hopper. The rim is broken, the discharge pipe from the sink ends above the drain, and half the water splashes on the edge of the hopper, and enters a void behind the broken top of the hopper. I enclose a link to photos. Stivulya / Стивуля 1. If I mend top, concrete round, extend pipes, is that sufficient? Drain appears to drain normally. 2. Is it legal / good practice to drain kitchen discharge and extra rainwater downpipe into pipe originally intended for rainwater? 3. Presumably the drain is joint responsibility of me and neighbour?