Hi Katetea:

Thanks for keeping in touch.

I do not know about England plumbing, necessarily, but I do know that all fixtures need to be vented.. so when they tell you pipe doesn't have to go to roof and it is "sealed off"... they are wrong! Once again I point you to your local building/plumbing inspector...ASK HIM if vent pipe from kitchen sink can be "sealed off"...I am quite sure he will not like that.

The "vent" for dishwasher... do you think they mean a dishwasher AIR GAP fitting... some places, even here require air gap fittings to dishwashers... MOST places, however just ask plumbers to create a high loop so that water from sink can not drain back down and into dishwasher. This works just fine. Your sink looked high looped. Anyway, see what landlord says about this VENT for dishwasher... keep us posted.

Hello everyone
I think they have finally fixed the problem here! The plumber came by yesterday and put a trap on the dishwasher, kind of looks like the picture you sent on here on the first page,mass. He said that without that on it there was nothing stopping the smells coming in. Its only been one day but so far it looks good! No odors here last night after running the dishwasher and running the hot water down the sink a few times. So hopefully its fixed... finally! Once again I want to thank everyone that has replied to my questions on here.. They were all so helpful and I really do appreciate it!
~ Kate

Hmmmm.. thought the dishwasher was hooked into your kitchen sink drain trap..? Hey, I'm just glad it is fixed.. *crossing fingers*... thanks for update!

No, it was separate. The landlord had the dishwasher installed after this place was built. Im not exactly sure where the hose goes to from the dishwasher (its goes in and behind the wall) but its not connected under the sink.

Hello
This will be my last post on this question, but just wanted to let you know it IS fixed! Hard to believe it took them over 10months to figure out it was the lack of an airgap trap on the dishwasher. We are still moving in a week but at least we found out what was causing the odor.. thanks to all of your help! This is a great site! And once again, thank you so much for all your help on here!