28mm to 26 mm Push-Fit Reducer

Another bit of plastic?  Oh yes, and you probably need this bit more than you think.
One end of this push fit reducer slides into the sink waste, the other end fits into the 28mm waste hose and it’s just as sexy as it sounds.  Buy one and you’ll attain heights of hither to unforseen levels of caravan plumbing nirvana.

Maybe not, but the kitchen unit should stay dry.