Thought I would take a shot at it since the contest states there will be 60 winners and there's only 41 entries currently(well 42 after I submit this entry.)

I was thinking that a flexible PCB would be nice to use for the electrodes.  The idea is fairly simple: simply have two sets of exposed traces run close to each other and have a set of pads for soldering the wires that run to the Water Alert board. The PCB could then be simply taped to the floor or another surface that needs to be monitored. I did a simple sketch of it(please excuse the very crude drawing.)