Katherman, 13, used Q-tips and petri dishes, swabbing the spigots of four fountains and sampling one toilet, dunking the cotton in the bowl's center and then dragging it around the rim for a complete sample.
And that was her mistake. If the toilet had chemicals residing in it continuously (not atypical), then she dosed the swab with antibacterials as she collected her sample. Better technique: just swab around the rim, or perhaps just the flush lever or front of the lid.
Not that I'm a germophobe or anything, but the vilest contact point in a public restroom is usually (a) the handle/push-plate on the inside face of the door or (b) the faucet handles.