Ok, so being very clever I syphon into a bucket, go tip it out and then return for another, and another....
Taking water from the tank last week I'm pouring a bucket into the sink (i know, good for the garden, but it was raining) when I notice that the water isnt draining away too quickly.
I put the bucket on the side, go under the sink, and with my Mr Clever and Mr Cautious hat on i wrap the undersink trap in towels and remove it....oh I'm so clever, no water spills.
I find some unmentionables along with a few bits of plant in there....yep, I'm clever! So I remove all the build up from the trap, smile at myself, then pour the remainder of the bucket into the sink..........with a nice view of the trap still sitting on the side i get a 'moist' feeling under foot, apparently you have to put the pipes back otherwise the water goes over all the cra....i mean carefully stored items, under the sink, and all over the floor, and all over my feet.
I've packed away both the clever and cautious hats....wont be needing those again