I have a dumb question for you. Isn’t shit and piss just dumped into the ocean? Or is it stored and removed when ships dock? Seems your post indicates the latter which I find surprising for some reason.

That’s a bold assumption. At the time of building most of them probably were mostly up to their local codes. Did a few get through inspection due to bad inspectors, bad/lazy tradesmen, etc. Sure. But 90%?