Rebuilding the WC - PVC pipe or hose?

[AuroraGH]

Or both? My boat's WC was oddly configured and the toilet was put rather far from the tank. In the redesign, the toilet is nearly directly above and to the side of the tank. Shorter runs for sure.

The old setup had quite a mix of 1.5" PVC pipe for both the run from the toilet to the tank and also from the tank pickup to the deck plate.

I'm going to be replacing all of it. My preference is to run PVC as much as possible and only use hose connections where there are tricky runs that are easy to access for replacement because hose permeates and PVC (as far as I know) is forever.

Is there any reason in particular to avoid PVC pipe (white sched 40 300 psi stuff was used)?

[model 10]

Some pvc fittings have a much shorter fit, like almost an inch less. I think they are using white pvc for drain systems now. With no pressure do deal with they have less glue surface. I really like using a bit of hose glued into the pvc fittings. Like you said, at bends etc., also at the head itself and any place where there is movement.

[Lepke]

When I use plastic pipe, I always use schedule 80 - thicker walls and not much difference in price. Schedule 80 is for higher pressure, but also resists cracking better. In a vessel there is always some flexing of the hull. In the case of a toilet, there may be some movement when the toilet is sat upon.
Also, when plumbing marine toilets, I usually add some way to flush the lines should the toilet pump fail.

[Nicholson58]

Thicker walls - lower permeation. PVC hark pipe is excellent for this. Consider Raritan hose where you need it. Ranked one of the best for permeability and is easily the most flexible sanitation hose you can get.

[Glen Ballou]

I replaced all of the hose on our 2 heads with pvc in 2006. I installed Raritan electric heads at the same time. The heads have built in macerators so I used 1 inch pipe from the head (more flexible) and 1.5 inch pipe from the holding tank to the hull and deck pump-out. I put a 1 inch long flexible hose between the pipes and the toilet, holding tank, and thu hull and deck fitting, reducing stress on the pipes. Have over 14,000 miles since then much of it blue water and had no problems with either the piping or electric heads.

[skipgundlach]

PVC will never stink. It will hold up to 3-5000 impacts (or, at least, ours did) in 8-10' surf on a flat limestone shelf dry at low water, over 3 days.

Unfortunately, my installations are spread throughout my early refit pictures, or I'd show you (you can still meander and see them, but it's a LOT OF PICTURES!

It will behave like hose and calcify, however, if you don't do what we do, because urine and sea water make calcium in PVC, too.

Unless...

Pump as you're going. Then calculate the volume of the hose, and pump about that much rinse water through (to remove all the urine), AND, then, give the same number of dry strokes, until you get burps at the other end.

The result will be that you now have a dry stack pipe, if your antisiphon valve works.

We've used ours for 8 years; I had to take both of them apart for other chores (not potty); the exit, for example, in the forward head, all the way next to the Y valve, was clean other than a very slight discoloration on the very bottom.

Pic here:

Pictures: Flying Pig Refit 2011-2012/Fishfinder and SSB Redo

There are two pictures which show the end of the PVC, and a couple which show the end of the through-hull nipple. The ones with the pvc show a black circle; that is the usual drain-pipe rubber coupling for drains.

I butted the pipe to the Y carefully, and it turns out that standard 1.5" hose is the same thickness of PVC, which made for a seamless butt by adding that much hose over the Y or duckbill exit. A clamp directly over that butt keeps any possible odor from making it out, and the other ends of the coupling with clamps makes sure that if there IS a leak, it's contained.

It's easy to slide the coupling back up the pvc if you need to get to it, such as, on the other end, to rebuild the toilet and replace the duckbill.

So, my systems have all PVC to and from toilet and Y; no possible odor, and with the flushing routine, also no size loss from calcification.

YMMV - but I'm convinced that our installation will outlive us; if it can stand our wreck, it can stand any normal sailing.

L8R

Skip

[HopCar]

I sell hose so you would expect me to tell you to run all hose. I won't.
Run PVC where you can. Use Raritan Sani-Flex or Trident 102 hose where you can't.
Raritan SANI-FLEX Odor Shield Hose 1-1/2"

The tricky part is joining the PVC to the hose. You might be able to force 1-1/2" hose over 1-1/4" PVC and clamp. I'm not real comfortable clamping on a smooth surface like that.

I'd glue a threaded fitting to the end of 1-1/2 PVC and use a hose barb to make the connection.
Banjo Polypropylene Straight Hose Barb Pipe Fittings

[Scout 30]

Or you can avoid the hassle altogether.


C-Head portable composting toilets

[colemj]

Originally Posted by HopCar

I'd glue a threaded fitting to the end of 1-1/2 PVC and use a hose barb to make the connection.

I agree with this. HOWEVER, when plumbing one of our tanks, I did not have a PVC threaded fitting on hand for the tank fill pipe and I REALLY wanted to get it hooked back up. Since I had a 1.5" rubber PVC joiner on hand, I used that to connect the PVC pipe to the tank fitting - with the expectation that I would change it to a PVC threaded fitting in the short future.

Then I forgot about it. It has been many years now and that rubber coupling has neither leaked nor permeated. I think they do join household sewer pipes with these.

Mark

[model 10]

Originally Posted by HopCar

I sell hose so you would expect me to tell you to run all hose. I won't.
Run PVC where you can. Use Raritan Sani-Flex or Trident 102 hose where you can't.
Raritan SANI-FLEX Odor Shield Hose 1-1/2"

The tricky part is joining the PVC to the hose. You might be able to force 1-1/2" hose over 1-1/4" PVC and clamp. I'm not real comfortable clamping on a smooth surface like that.

I'd glue a threaded fitting to the end of 1-1/2 PVC and use a hose barb to make the connection.
Banjo Polypropylene Straight Hose Barb Pipe Fittings

I'm confused by all that.. 11/2" pvc hose is the same outside dia as 11/2" PVC pipe. You don't need any special fittings. You glue the hose just like you would the pipe.

[Rustic Charm]

Originally Posted by Scout 30

Or you can avoid the hassle altogether.


C-Head portable composting toilets

I don't quite understand the claim that composting toilets are 'hassle free'.

You still have to empty them, and you still have to empty or 'hold' the urine.

It's much easier to either hold it in the first place and dump overside as you go and when you can. I can't personally see the benefit of these composting toilets. And the claim to 'no smell'? I've not seen one installed on a boat, but I've come across them installed elsewhere and when you open the lid, they smell and look unsightly.

[HopCar]

Guy, 1-1/2" PVC Pipe has an outside diameter of almost 2 inches. 1-1/4" PVC pipe has an OD of a little over 1-1/2". I'm too lazy to look it up, but I think the measurements are 1.9 inches OD for 1-1/2" PVC Pipe and 1.6 for 1-1/4" PVC pipe.

If you're joining hose to pipe, the OD of the pipe has to be the same as the ID of the hose.

Mark I like the idea of using one of those rubber couplings to join the PVC Pipe to the hose barb on the tank. I'll remember that trick.

Might even work to join a piece of hose to PVC pipe if the hose is rigid enough. I think that needs some testing before we recommend it.

[Dsanduril]

HopCar,

I think Guy is referring to something like this:

1-1/2" White PVC Flexible Pipe | U.S. Plastic Corp.

Sometimes called hose, and sometimes flexible pipe, you just glue a coupling onto the end of your rigid pipe and then glue the flexible PVC into the coupling - no barb required. It's pretty much the same as PVC hose, just built with dimensions to match Sch. 40 pipe so it can be glued together rather than using hose fittings.

[Simply Sailing]

Originally Posted by Rustic Charm

I don't quite understand the claim that composting toilets are 'hassle free'.

You still have to empty them, and you still have to empty or 'hold' the urine.

It's much easier to either hold it in the first place and dump overside as you go and when you can. I can't personally see the benefit of these composting toilets. And the claim to 'no smell'? I've not seen one installed on a boat, but I've come across them installed elsewhere and when you open the lid, they smell and look unsightly.

I think what he may be getting at is that you can go much longer without being hassled by emptying a composting head. We make it 6 weeks, which is a lot longer than any holding tank that would fit on our boat would last for two full time liveaboards. We don't have any smell, but ours is an Air Head with a fan and an external vent, so there is no smelly anaerobic bacteria in there. As far as how it looks, there's really no reason to look except once every 6-weeks when you empty it. Maybe you are referring to the larger systems like at National Parks? The ones I've seen installed in houses are usually on the same principle and I agree, they do smell. On a boat, they are much less smelly and simpler, if you have the right kind.

[model 10]

Originally Posted by Dsanduril

HopCar,

I think Guy is referring to something like this:

1-1/2" White PVC Flexible Pipe | U.S. Plastic Corp.

Sometimes called hose, and sometimes flexible pipe, you just glue a coupling onto the end of your rigid pipe and then glue the flexible PVC into the coupling - no barb required. It's pretty much the same as PVC hose, just built with dimensions to match Sch. 40 pipe so it can be glued together rather than using hose fittings.

This is what sanatation hose is. PVC hose that is the same size as pipe. Some brands are better than others with the smell thing. It glues together perfectly with regular sch. 40 pipe fittings. Every hot tub around is made this way. They just use the cheaper hose.