Nobody has said anything about whether yachts treat waste. I said that they don't reuse water. Treating waste for discharge and separating water from the waste are wildly different things. In some ports yachts can pump out their tanks just like RVs. Where discharge is allowed, the waste most assuredly goes overboard. USCG approved marine sanitation devices kill all pathogens. 

You seem to be under the illusion that yachts only dump water, while waste solids eternally gather onboard. This is physically impossible.