What I've learned about my toilet

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Sorry if this is the wrong palce to post this, but I just wanted to share what I've leanrned about my toilet over the years...

When I first got the boat, I thought the raw water side of the toilet pump was broken becasue it simply wasn't pumping much if any sea water into the bowl.  So I rebuilt it, but that didn't fix it.  I later discovered that it was becasue of the vent in the anitsiphon loop.  The vent was causing the pump to suck air.  I discovered that if you put your finger over the small vent while pumping, the pump works great!  Luckly, it's pretty easy to open the cabinet under the sink, feel for the small vent and cover it while pumping with the other hand.

But, the toilet would stink when I arrived at the boat becasue of the dead stuff left in the bowl full of sea water.  Decided to use only fresh water.  I tried several replumbing experiments like connecting the toilt water intake directly to the fresh water system.  Doesn't work - not enough GPM.   For awhile I had the toilt water intake connected directly to the sink drain so one would fill the sink with fresh water then flush.  This works.  Thought about putting a Y valve so the toilet water could be switched from sink drain to raw, but that cost money.  I wanted the option to go back to raw water in case I was low on fresh water or maybe up in the Delta where the sea water is fresh.  Then I realized, I wasn't pumping raw water anyway unless my finger was on the antisiphon valve.  Went back to stock plumbing and now, for a fresh water flush, just pull the sink hose out and fill the bowl.  For a raw water flush, finger on the antisiphon valve. 

But the stink problem wasn't solved.  Still the dead raw water in the bowl when I got down to the boat.  Why?  I figured out that the antisiphon valve on the black water toilt discharge wasn't working and raw water was siphoning back into the bowl.  I cleaned the little rubber check valve, but it was still not working.  So now after using the boat, I just give that antisiphon valve a quick loosening and "burp" the aintisiphon loop.  I can hear the air and the pipes drain down to seal level.

In summery, for fresh water flush, pull the sink hose and fill the bowl.  For a raw water flush, finger over the raw water in anitsiphon valve.  Burp the black water out antisiphon valve at the end of the day.

The toilet hand pump pumps much more freely.  I think the raw water in side of the toilet pump takes more force than the black water out side of the pump.  So if the raw water in side is not used becasue we've filled the bowl with fresh sink water and the pump is pumping air from the anitsiphon valve, it pumps very easily.

And no more stink!

David Sanner

I put a simple T just above the stopcock on my sink drain and connected
the fresh water line to the toilet there.

I normally leave the stopcock closed and flush the toilet by running water in the sink
and pumping it through.

If I want to use sea water or drain the sink overboard I just open the stopcock.

Works well...    as far the anti-siphon valve I always thought there were suppose
to go between the pump and the bowl to the valve is under pressure when the
bowl is being pumped and drains when you stop pumping.

Best thing I've done lately is replace the entire pump unit (everything but the bowl)
which I found at nearly the same cost a pump rebuild kit. 

David Sanner, #611 1988, "Queimada" San Francisco Bay