It depends on how many people peed in it.
If I get some spare time I will set up my conductivity experiment again. It was a white bucket with two one foot #10 probes in contact with water and 8" apart in series with a 60w light bulb.
I did this a while ago and was surprised at how little salt it took to get the bulb to glow. I now have the ability to test for total dissolved salts content. I can't find my results but I did plot current and voltage drop for various solutions.