I think Charmin is trying to be discreet here. The problem is likely not urine, but feces. In most cases, urine is fairly harmless, even beneficial to the ocean life because it contains urea, CO(NH2)2, which is a mild fertilizer.
Feces, on the other hand, is loaded with coliform bacteria, such as Citrobacter, Enterobacter, Hafnia, Klebsiella, and everybody’s favorite Escherichia, especially E. coli.
Feces contains a lot of other nasties, including viruses, protozoa, parasites, etc. But it’s easier to detect the quantity of coliform bacteria per liter.
Public swimming pools are often haunted by coliform bacteria, and have set limits to how much they can have before they have to dump out their water, get all fresh, and then chlorinate the heck out of it.
Entire stretches of the California coast are sometimes put off limits because the ocean water has too much in it.
So I said to the lifeguard, “What’s the big deal? Every body pees in the pool!”
He says to me, “Yeah, but they don’t do it from the diving board!”