And yet surely you have urinated in a public swimming pool or shower...

Surely I have not. Cryptosporidium strains have now evolved the ability to withstand chlorine environments thanks to the people who did that, and as I train for triathlons or visits sprawling water parks I always thank them silently for giving me a reason to take it slow and not to overdo fancy tricks or racing too quickly to chance swallowing any of the brackish, disgusting water.

Before the Clear Lake outbreak of hemorrhagic E-coli I was with my Boy Scout troop daring a speedboat driver to pull me on an inner-tube faster than 45mph, and after he whiplashed me into the air by snapping the rope across his wake after pulling a 180 degree turn, it was only a few hours later that I began vomiting up blood, having swallowed some contaminated lake pollution. A 50% survival rate after infection exacerbated by them giving me scorched-earth antibiotics (now highly non-recommended for similar cases). I spent weeks writhing agony as little monsters tried to eat my intestines. Dehydrated and in excruciating pain, doped up on morphine my mind somehow taught itself to function in the adverse circumstances presented to it, and it decided to not undergo this trial again.