The world has changed and it was while rebuilding Nellie's sanitation system that this point was driven home in some interesting ways. The old sanitation design (see first diagram below) reflected the mores of its time. Nellie's new design (see second diagram below) reflects today's rules and maybe, even some of tomorrow's. Almost everywhere in US waters it's illegal to pump the head directly overboard. In fact, where we normally cruise, the inland waters of the east coast, even having an open head through-hull is a fineable offense. So, how does this affect Nellie's sanitation design? Surprisingly in some dramatic ways, and mostly for the better.
When, by law, a normally-open through-hull becomes normally-closed, it's a game changer and there's a cascading affect on the sanitation system's design. The old design required an anti-siphon and a three-way valve. The first kept the boat from flooding via the always-open thru-hull. The second allowed toilet waste to bypass the holding tank and go directly overboard via the open thru-hull. Redesign the system about a closed thru-hull and things get simpler. Now all head effluent goes into the holding tank. The holding tank can be emptied with either a shore-based vacuum pump or into the sea via an on-board pump. Here's the up-side: by removing the anti-siphon and the three-way valve we eliminated 30' of hose, a dozen hose clamps, and myriad sources of potential 'stink'.
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| Head plumbing layout before the latest modification |
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| New head plumbing layout |
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