Sink problem

[queries]

When I empty the washing-up bowl the water sometimes sort of backs up and spits out of the joint between the plastic piping leading from the washing machine and the pipe - it also leaks at this point when the washing machine empties. I am presuming that there is a blockage in the u-bend - but the plastic joints on this bit are proving impossible to undo - anyone know a way I can get these undone without either having the expense of a plumber or cracking the plastic itself!

[alavahalf]

If the joints are smooth they are glued and you can't undo them...if they have what looks like a large nut at either end, then they can be undone.
Failing this go into a hardware store and ask for a spring to unblock waste pipes/sinks.
Should'nt be more than a fiver.
Just push the spring down the waste and force it round the u-bend...push it, in and pull it out, and wiggle it about if you want...they usually go with a bit of effort.
A sink plunger will also help...and when you think you have cleared it...put some sink or drain cleaner down the waste...

[queries]

Great - thanks - B&Q this evening!!! Any tips on how to loosen the threads on the ubend if I eventually have to?

[buildersmate]

You can get a lot more turning force on them if you wrap the nut in some improvised rubber sheeting material - it improves the friction between the ABS plastic and the hand. A large-jawed adjustable spanner could be tried but may be counterproductive - exerts too much force on the plastic components.