Allright it's been over a week. Here it is:
He had the poison on his hands at first of course.
He turned on the water with his poisoned, the poison was then transferred to the knob in which he used his poisoned hand to turn on.
When he was done washing his hands he used the same knob to turn off the water, but the poison was still on the knob.So then when he turned the water off the poison was transferred right back onto his hands so while he was eating, the poison was still on his hands, it got into his body, and he died.

Simple enough right?

Want me to give it away or do you just wanna leave it and figure it out urselves?

puchiko's got one part of it right, how is the poison still on his hands though?

Ummm....He cooked his food with the same water he washed his hands with!!!!! O___o
lolz, I have no idea X3

I died from the poision, washing your hands with water and soap dosen't remove very many poisions, infact, cyinide can only be removed by Bleach and another chemical, but een then there's no gurantee that it will be gone, -AsagiTaichou visit my site for a good fanfic