Sewage Hose or PVC Pipe ?

[a64pilot]

While ingenious and obviously it has worked, it doesn’t have an air gap, which I think you need to be absolutely sure you don’t get any contamination.
Peggie suggests just plumbing the head to the sink, that way just put water in the sink to flush the head. My assumption is the thru hull is closed to keep water in the drain line. That of course completely disconnects the water supply from the head so very little to no chance of contamination.
You may consider Raritan’s fresh head conversion which does connect directly to your pressurized fresh water source and has a vacuum break for that air gap. Real easy to service too.

[David M]

In my opinion, PVC pipe is too brittle to be used below the waterline.

[peghall]

Peggie suggests just plumbing the head to the sink, that way just put water in the sink to flush the head. My assumption is the thru hull is closed to keep water in the drain line. That of course completely disconnects the water supply from the head so very little to no chance of contamination

That needs some clarification! 30 years ago several boat builders used the same thru-hull for the head sink and toilet intake line. I got the idea from a Tartan owner whose system was plumbed this way. It's a simple an inexpensive mod that's easy to do on most boats...the head sink and the toilet do have to be on the same side of the keel and the head sink drain thru-hull has to be below the waterline.

Reroute the toilet INLET line to tee into the head sink drain line as close to the seacock as possible...it needs to be below waterline, allowing you to continue flushing with sea water most of the time, but also provides a safe way to rinse it out of the ENTIRE system--inlet line, pump and channel the rim of the bowl--before it can sit, stagnate and stink. Fresh water poured into the bowl only rinses out the toilet discharge line...the water doesn't recirculate through the intake, pump and channel in the rim of the bowl (you wouldn't want it to!) To rinse out the entire system, close the thru-hull, fill the sink with CLEAN fresh water (never use gray water!!), flush the toilet. Because the thru-hull is closed, the toilet pulls the water out of the sink. Or you deplete your fresh water by filling the sink with it for every flush. A totally safe way to supply fresh water to the toilet without the need for separate flush tanks and/or pricy chemicals chemicals and gadgets that don't work.

Also has the added advantage of providing a very simple way to winterize the toilet and system: close the seacock, pour the antifreeze down the sink and flush it through. Job done.

[skipgundlach]

Originally Posted by David M

In my opinion, PVC pipe is too brittle to be used below the waterline.

I have an inexpensive test for those considering PVC but concerned about the above despite our wreck's demonstration:

Go to Home Depot.

Purchase two sticks of 2' (found in bins in the PVC aisle) 1.5" and an ell.

Glue it up properly.

Have two friends stand on the ends of the sticks (to keep it from bouncing and hitting you during your experiment).

Take a hammer and do your worst.

Report back your experience.

I have not done that. But I believe you'll wear yourself out before you break it....

[HopCar]

Skip, I was at Home Depot last night to buy PVC for an unrelated project. It’s cheaper to buy a ten foot length than two 2 foot lengths!
Ok back to the topic of this thread.

[skipgundlach]

Originally Posted by HopCar

Skip, I was at Home Depot last night to buy PVC for an unrelated project. It’s cheaper to buy a ten foot length than two 2 foot lengths!
Ok back to the topic of this thread.

LOL somebody has to cut it!

[BlackHeron]

I installed a hybrid hose/PVC septic system in our boat. The boat came to us with the holding tank 10 feet away from the head. That is too long to run hose without many issues with standing pooh in the system and permeation, so I ran about 8 feet of PVC from behind the head to the tank in the lazarette using the sealand adapters on both ends with a cleanout T at the higher head end, and just a short chunk of hose to drop into the holding tank on the other.





I have approximately 6 feet of hose in total, and it is all mostly vertical runs where the pooh can't sit. There is about 3 feet from the joker valve at the Raritan PHII head to the anti-siphon loop. The 8' unbroken piece of PVC is well-supported by bulkheads on both ends, and 3 J-straps in between so it is supported every 2' and is not under any spring tension at all. If it ever fails/cracks I have easy access to the pipe the entire run and carry spare pipe and couplings. Repairing will be as easy as repairing a hose. It can be easily rodded out as it is a straight shot from one side to the other. A little bit of vinegar maintenance should prevent that hopefully. So far after one season of use it has worked marvelously. It doesn't take a lot of pumping to clear the short section between the head and the loop. The PVC section is slightly pitched and self-clears down to the 20 gallon tank in the port lazarette.