Funny article, but the last picture is pretty awesome.

I was really NOT in the mood for another chemistry lesson tonight. First attempt at sump-pump water level detector (by conducting between wires at different heights in the well) ended when I found that after a day, the slight exposed copper + solder + whatever is in my water was generating a little over 1V on my wires! Second attempt has now failed as I observe that the resistance between two STAINLESS STEEL wires (least reactive metal I could think of) will rapidly RISE from 2K to over 22K, almost linearly with time! Also, it shows .05 volts, with the only difference between the wires being their height in the well. Maybe there is just something seriously wrong with my ground water...