View Full Version : Jabsco Toilet water supply

10-11-2015, 09:31 PM
All righty, I replaced one of my Electric Jabsco toilets, rebuilt the other. As I was reading the instructions I noticed that Jabsco says to NOT have the toilets connected to your fresh water system.......well, that is exactly how mine were plumbed. The Fresh water system supplies the toilets and all the faucets and showers.
This boat was new to me this summer, its a 1979 Bluewater Sports Sedan.

My question, can I install some kind of check valve in the supply line to keep from cross contaminating, or should I set up a whole separate water supply for the toilets. Currently, they are only supplied through the boats fresh water system.

10-12-2015, 07:39 AM
I think that you will find a "back flow" preventer (check) device built into the Jabsco if you look hard enough.

10-12-2015, 08:48 AM
I have 2 new jabsco 37010's in our boat and they don't have a check valve.they constantly lose prime.

10-12-2015, 03:05 PM
A back flow preventer prevents back flow to supply if the liquid level in the toilet gets higher than the inlet to the unit. If your unit pumps from the lake an inlet check valve might help your situation. Two different situations.

10-12-2015, 03:53 PM
I have the same toilets as 42gibson, with the same losing prime problem. The instructions for the new toilet, and as I read them online, distinctly say that they are not to be connected to the boats fresh water system. In my reading I think I saw something about purchasing a back flow preventer for the Jabsco toilet, but that in the instructions for a manual toilet, not my electric model.

Here's what I was thinking if a check valve is not safe. We have two holding tanks with insufficient venting, each pumping out from opposite sides of the boat. A pain in the rear. My idea is to eliminate one holding tank replace the other with a larger capacity tank, proper venting for both toilets. Install a new "toilet water tank" that fills from the side of boat inlet that is no longer being used by the eliminated holding tank. I guess I'd also need another water pump too. I have the space and am able to do the work myself, except for the electrical. I was already going to change out the sanitation hoses this winter.

So, as I see it, check valves or bigger project? Unless I am missing something, which is quite possible.

10-13-2015, 07:21 PM
Why not change to lake water. No tank - eliminate weight

10-14-2015, 10:50 AM
Why not change to lake water. No tank - eliminate weight

I like this idea. My heads flush with lake water and always have. In addition to the weight benefit that OHB mentioned, I like that as long as my boat is afloat, I will never run out of water to flush a head. It gives peace of mind to never have the prospect of running low on fresh water and having to weigh flushing the head vs getting a drink. As your question points out, you also eliminate the possibility of having your heads contaminate the water you're drinking.

There are a few downsides to using lake water to flush. The biggest is that lake water can hold bits of sediment. Even though the sediment particle size is smaller than sand, it can be big enough to shorten the life of seals. I had issues with that until I installed a 5-micron filter on my lake water intake. Second, lake water can sometimes have color to it. Not a lot, mind you, but enough that it doesn't look crystal clear in a white toilet bowl. My heads don't sit around with water in them but if yours do, that could be an issue. Finally, lake water can sometimes get a rotten egg smell from sitting in your pipes for too long. That isn't a huge issue given the intended use of a head, but you might notice the smell from time to time.

All in all, I will gladly take the minor downsides of lakewater flushing for the big gains that come from it.

10-18-2015, 07:01 PM
The reason they don't want you connecting to the FW tank is because there is a possibility (however remote) that toilet water could flow back to the FW tank.
However they DO make a "fresh water flush" version. That toilet and the "raw water" toilet are 95% the same; you can convert yours by ordering and installing the appropriate parts.

Losing prime is a bit different. That noisy rubber impeller isn't airtight and on toilets mounted above the waterline (most houseboats), the water can drain back leaving the pump "dry". For some reason check valves don't work (been there).

The solution is simple enough. Remove the rubber impeller and set it aside, and put the pump back together. Install a 3gpm or greater pressure pump BELOW THE WATERLINE, and plumb this to the intake to the old pump, and wire it in to the switch so it runs when the button is pushed. The pressure pump being below the water line will never lose prime, and will push the water up through the empty pump chamber in the toilet and from there into the bowl (done that). This works just fine and it's a WHOLE LOT quieter than the original toilet. OR you could bypass the empty pump chamber and go directly from the pressure pump to the bowl (haven't tried that).

Eventually if/when the original pump motor fails, get the "quiet flush" motor; it will have a shorter shaft and you can dispense with the now empty pump chamber (done that too). You now have a "quiet flush" toilet.

Download the diagrams for the various models of the Jabsco toilet and you will see what I'm getting at.

If you STILL want to run your toilet off the FW tank you can do so, they have a "solenoid valve/vacuum breaker" for the FW model that you can adapt to your existing toilet, in place of the "pressure pump" mentioned above.

Sorry but none of these conversion are "cheap"... (it's a B.O.A.T. what did you expect?)

10-23-2015, 09:21 PM
Thanks guys! I now have multiple solutions to consider. I appreciate the responses.