I replaced my toilet with a Jabsco electric , with masserater two years ago. I hooked up a 6 gal. plactic can above the unit as a tank and fill the tank with water from the boat water system. I covered the tank with plywood pole wrap , stained it and it's a close match to the finish inside the head. I have a manual shut off valve that I open when I push the masserater button.......it works fine. Felt like Rube Goldberg when I was done!

I found this information useful, so I'll add it to my post. I talked to the JABSCO tech department and they do not recommend using the onboard water system as a water supply for the manual head. Apperently during the Flush cycle there is the possibility of contact between the "fresh" water supply and the "waste" water because for a few moments in the flush process they share the same pressure piston even though in different compartments of the piston. If there was a slight scratch or defect in the piston wall the fresh and the dirty water could come into contact. Also, according to the tech, if you use lake/river water as a grey water source, the bacteria from the grey water can add to the odor problem over a day or two. The solution... I can put a 9 gal holding tank in the V-birth as a grey water reservoir to use for flushing, then discharge into the onboard wast water tank. Add disinfectant directly to the grey water reservoir. I'll re-post after the installation. If anyone has installed this type of head, I would still like to hear from you. Thanks.

Manual JABSCO update. I got the unit installed. Operates really well, even moves T.P. to the holding tank. Only one glich worth noting. The toilet is 11 inches high at the rim, a standard is around 15", so I had to build a wooden box/rectangle to raise the unit 4 inches. They sell a pedestal to raise the unit, but I didn't find out about it until I was pretty much done, and there was no mention of the low height when I was researching the purchase. For my fairly low usage, I think this is going to be a good head. misson complete.

One more post for the JABSCO manual flush conversion. I used a plastic 6 gallon marine fuel tank for the grey water reservoir. I priced holding tanks, and they are fairly expensive. The pick-up tube in the fuel tank goes to the bottom ot the tank and the vent provides needed air flow for suction. A $23.00 solution.

Hey Fastjeff, I left out one more detail of the installation. When connecting the waste water line to the holding tank it requires a "Number two" screwdriver. (snicker) I couldn't resist either :)