Doing without anti-syphon valves for toilet

[LittleSister]

I'm pondering putting 'supplementary' shut off valves within the heads compartment for the inlet and outlet hoses of a replacement toilet to avoid syphoning, because the seacocks for these are not very accessible, and running the hoses up to anti-syphon valves at deck height would be aesthetically and DIY challenging (there's a sliding sink and high level lockers in the way), and running them part way up would be neither fish nor fowl.

Any views as to whether fitting such shut-off valves is unwise, unnecessary or whatever?

The background is that my relatively recently acquired boat has somehow survived without high level (or indeed any) anti-syphon valves for nearly 40 years, and I previously owned boats without them (I wasn't aware of the 'need' at the time) and never had a problem, but I have now twice had the toilet fill and spill (the rim of the bowl is approximately at sea level, as it were).

My TMC toilet doesn't pump at all well, despite having replaced the seals and valves in the pump, and that may be part of the problem. It's being replaced by a Jabsco Twist&Lock (because a Lavac would need high level pipes).

 

[xeitosaphil]

My understanding is you only need a high rise Syphon loop in the system if you leave your seacocks open all the time while sailing. I actually close mine when sailing so never had the toilet fill up.
I would have thought if you intend putting shut off valves in the inlet/ outlet lines you could do away with the high rise loop?

 

[Uricanejack]

I re plumbed my system. I replaced the anti syphon, putting the new one in the original position. On my boat the anti syphon is under the forward V berth just above the water line. Truthfully, I didn't know what the heck it was until went to the chandler. To get replacement parts. The surveyor had noted it on the survey. It was on the list of things to fix required by my insurance.

My system is the simplest acceptable to USCG. And my Insurance co. With a Y valve to select OB or holding tank, To sail in US waters I am required to have a holding tank. I can discharge direct OB most of the time but if I enter a river or a no discharge area I am required to lock the valve to holding tank.

The discharge line from the head. Goes to a holding tank. Via a Y valve half way along. This line is just under the V berth.
The straight discharge, from the Y valve goes to the holding tank.
The lower discharge from the Y valve goes down in a loop first to the bilge then back up to the anti syphon at the same Hight just under the V berth. Then straight down to the OB discharge or Sea Cock.
The holding tank has the inlet at the top and a discharge connection at the bottom which goes in a direct line to the pump out on deck.
The Y valve has a lock loop on it to seal it to the tank position.

I could put a second Y valve and discharge to an OB after the holding tank but have not done so due to limited space and more complex plumbing and I almost never go to restricted no discharge areas.

I still keep to tradition of leaving the pump switched to dry bowl and presume its still possible to back fill. Particularly since I think it could become blocked by scale. Never had a problem though.

Older boats I sailed where we had the bowls fill occasionally when it was left on wet bowl probably didn't have an anti syphon

 

[Tintin]

The perfect method is high rise loops.

Or shutting the seacocks every time.

I see no issue with secondary valves.

 

[RichardS]

When I replaced all the hoses on both my toilets a couple of years ago I dispensed with the loops and anti-syphon valves completely. It made the plumbing much easier and cheaper. However, on a cat I don't have a problem with heeling and the boat and toilets sit higher against the waterline.

Richard

 

[Stemar]

No problem as long as you remember to close them and no one needs to sit on the throne while you're heeled the wrong way.

I forgot to close the head seacocks once and, a few miles out, suddenly realised that the cabin carpet was floating as the head overflowed. Cue diversion to noisy pontoon with a tap to wash everything instead of the intended quiet anchorage

I now have loops with anti-syphon valves

 

[Graham376]

I have now twice had the toilet fill and spill (the rim of the bowl is approximately at sea level, as it were).

One of ours (Jabsco) did that if the switch was left in the flush position, service kit cured it. None of our 4 boats have had anti-syphon valves and sea cocks remain open whenever we're on board for months at a time.

 

[prv]

I still keep to tradition of leaving the pump switched to dry bowl

If it's a Jabsco, then all that does is poke a sort of plastic finger into one of the valves on the inlet side of the pump, preventing it sealing and causing the inlet side of the pump not to work properly when the handle is moved. It doesn't do anything at all to prevent water flowing through for any other reason - if anything it makes it fractionally easier since there's one less valve for it to push open.

Pete

 

[johnalison]

If it's a Jabsco, then all that does is poke a sort of plastic finger into one of the valves on the inlet side of the pump, preventing it sealing and causing the inlet side of the pump not to work properly when the handle is moved. It doesn't do anything at all to prevent water flowing through for any other reason - if anything it makes it fractionally easier since there's one less valve for it to push open.

Pete

That may be true in theory but my experience was different. My inlet seacock is hard to reach and never gets turned off, so the inlet was prone to syphoning to just below the level of the bowl. Switching to dry was a temporary solution and did work. However, if the pump is left for a long time in this position the rubber flap 'forgets' how to return and the pump may not prime properly. For this reason, I have fitted an anti-syphon loop and routinely leave the pump on wet.

In general though, I agree with the posters who wish to do without anti syphon loops, since they are not always needed and much advice on the subject in recent years has been a bit precious. I can break the syphon in my outlet by pumping sufficient air out, or by opening the holding tank, which is vented.

 

[Graham376]

If it's a Jabsco, then all that does is poke a sort of plastic finger into one of the valves on the inlet side of the pump, preventing it sealing and causing the inlet side of the pump not to work properly when the handle is moved. It doesn't do anything at all to prevent water flowing through for any other reason - if anything it makes it fractionally easier since there's one less valve for it to push open.

Pete

Our Jabsco was filling with inlet water and the lever pushed to the right stopped it happening.

 

[LittleSister]

Thanks for all the comments.

Just to clarify -

The reason for the proposed supplementary shut-off valves is to be able to close these (in the toilet compartment itself) instead of closing the seacocks, because the latter are in two other locations, both too inaccessible to want to open and close every time the toilet is used. I recognise the potential danger if they are not closed off.

I agree that non-syphon valves are, in principle, the best option, but are not likely to happen on this boat in the near future for the reasons outlined.

I don't have a holding tank.

I used to leave the seacocks open whenever aboard a previous boat or two of mine with a Jabsco type toilet (Par-Brydon IIRC) and no anti-syphon valves, and never had a problem, though I don't know why.

 

[xeitosaphil]

This is something that I have considered due to my toilet outlet seacock being under the saloon berth cushion and not very easily accessed or convenient at times. It has occurred to me though that not only is it a good idea to regularly use the seacocks to keep them free and in working order, but it also allows you to keep a regular eye on its condition.

My boat is also 40+ years old so this arrangement must have been the norm in the day?

What you intend is a user friendly option, but I would still regularly check seacock to keep it free and check its condition.

Only my thoughts.

Philip

 

[stevie69p]

LM27 by any chance? If so, I have exactly the same issue. On a port tack beat, the toilet fills up via the water flush inlet. I just close that sea cock before sailing and open as required, but a more accessible valve in the heads area would be handier.

 

[LittleSister]

What you intend is a user friendly option, but I would still regularly check seacock to keep it free and check its condition.

Only my thoughts.

Your thoughts are very welcome. The seacocks will be regularly checked and operated - they will be closed every time I leave the boat.

LM27 by any chance? If so, I have exactly the same issue. On a port tack beat, the toilet fills up via the water flush inlet. I just close that sea cock before sailing and open as required, but a more accessible valve in the heads area would be handier.

It is indeed an LM27 (and what fine craft it is!). Mine have never flooded at sea (fortunately), but only when I have been moored up.

The water inlet seacock for the toilet on mine is (as usual, I think) under the saloon berth, which currently involves removing a cushion, lifting and sliding the lid of the locker underneath, and kneeling down to reach the seacock under the covered end of the locker. Fine twice a trip, but too tedious for every time the loo is used. I have contemplated creating a small hatch or door in the front face of the locker (as I know some others have done), to gain easier access, but it wouldn't deal with the outlet, and the fine LM woodwork, with its clean, uncluttered Scandinavian styling, is so nice it seems a shame to alter it.

The seacock for the outlet is under the sink in the wheelhouse, which involves removing the carpet(!), lifting a large section of the sole, and kneeling to reach under the sink (and also, currently, behind a battery).

Back to the anti-syphoning, LitleSister Marine Enterprises is currently preparing a patent application for its cunning arrangement of the toilet bowl and all being automatically lifted the full height of the heads compartment when not in use. The toilet is lowered automatically when triggered by a, er, motion detector.