Holding tank - No Y Valve?

Our boat was built when anything went. So each toilet can discharge directly overboard or to its own holding tank. Each holding tank can be pumped directly overboard via a macerator pump or pumped out by a shoreside facility. Where the toilets and holding tanks discharge is determined by Y-valves.

Every owner of the boat has elected to keep it that way, as have we. While we normally discharge the toilets into their holding tanks and pump the holding tanks out with shoreside facilities (except in BC) we like the fact that we have work-arounds in the event of a holding tank, pump, or plumbing line function failure.

We have no locks on our toilet or holding tank overboard discharge seacocks or the Y-valves. We've been boarded a few times by the USCG and they went through the whole boat each time.. They didn't care about the waste handling systems at all and made no comments on them or the valve positions.

So if the OP's boat was ours we would elect to keep the Y-valve in place and exercise it regularly to make sure if it was needed someday it would work.

windmist said:

I was going to see if there is a check valve designed for this application - maybe Sealand has one. I don't think I would have a solids problem as my boat has Tecma heads and they macerate on the flush.

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When the question of check valves in sewage lines has come up in the past Peggie Hall would always chine in with what a bad idea this is. IIRC, her explanation was that no check valve on the planet will survive functionally with sewage discharge going through it even if it's just liquid. The buildup that occurs in these lines will render the valve inop in a very short time and it could end up actually blocking or restricting the line in both directions.

Even very simple duckbill valves need replacing periodically for this very reason.