The bin in the upper left of the pic is my water bucket. Just drag the hose through the window and bam, 40 gallon fill-up. I cut out a hole and put a nozzle in to make things easier. All the trays drain into a communal bin under the table and i've got a small pump with an outlet outside that will start the waste-water siphoning into the gutter.
As for K'nex, I recommend the Big Ball Factory, assuming they still make it. It has just the right mix of pieces to build just about anything.
Whenever I need to spray something, usually the roots of a plant, I spray at the bucket. So whatever's immune to Phyton and Physan may be living in there.