Porta Pottie has very little flush water coming out

[Project_Mayhem]

My three year old Dometic SaniPottie 975MSD has always had good water pressure when the flush water button was pressed until last weekend. I suspect that someone accidentally refilled the clean water tank with vinegar. Now there's barely a trickle of water no matter how many pumps are used to pressurize the tank. If the fill cap is removed after pumping you can hear pressurized air escaping

I'm considering connecting a shop vac to the clean water tank not only to get the vinegar or water out but to apply vacuum to the tank in an effort to remove any potential blockages. Any thoughts or suggestions would be greatly appreciated

 

[Peggie Hall HeadMistress]

Two thing you said--barely a trickle of flush water now and air escaping when you remove the fill cap--leads me to believe that your problem is a blocked tank vent that's pressurized the tank, preventing flush water from going into it.

The blockage is most likely in the vent thru-hull. Heeling or an overfull tank can cause waste to overflow the tank out the vent, or if there's a screen in it, dust, pollen, salt etc can clog the screen. Although unlikely, it's possible that something has set up housekeeping it. Knock it out...screens cause more problems than they prevent. If no screen, use a screwdriver blade, ice pick--whatever works--to scrape it out. Overflowing out the vent can also create a blockage at the tank. Relieve the pressure, then remove the vent line and scrape out that end of the hose and vent fitting on the tank.

If you want to prevent future vent blockages, replace the "vent" thru-hull with an open bulkhead--aka "mushroom"--thru-hull. This will allow you to put a hose against it to back flush the vent line every time you wash the boat, and will also provide increased air exchange with the gasses in the tank, helping to create the aerobic environment needed to prevent odor out the vent.

--Peggie

 

[Project_Mayhem]

This is a porta pottie with MSD. To use this model you pump roughly seven times. This pumps air into the clean water tank and pressurizes it. Once the "flush button" is pressed, water is released into the bowl. After your done doing your business you pull a handle that slides a blade style valve and everything from the bowl falls into the holding tank.

The fill cap for the tank has an o-ring and possibly a pressure relief valve. There's definitely pressure built up after pumping as I can hear it escape when I remove the fill cap

 

[Peggie Hall HeadMistress]

...

The fill cap for the tank has an o-ring and possibly a pressure relief valve. There's definitely pressure built up after pumping as I can hear it escape when I remove the fill cap

Which is the main reason I suspect a blocked tank vent. Air in the tank wouldn't need to escape out the fill cap opening if it could escape out the vent.

--Peggie

 

[Project_Mayhem]

Air pressure pushes fresh water out of the tank and exits through a couple of nozzles at the top of the bowl. There's no air vent for the fresh water tank. If there was, water would never come out of the nozzles. It operates on the same principal as those misto cooking oil sprayers or possibly an aerosol can. There is a pressure relief valve on the cap in case someone decides to pump the air pump 100 times. I suspect that the pathway to the nozzles are blocked

 

[THECUSCUS]

have you filled the flush water tank completely full? I have that same potti, and someone pumped it up too many times and the extra pressure split the side seam on the flush water tank, causing water and air to escape. Only leaked water when filled above the crack. I fixed it with some epoxy.

 

[Project_Mayhem]

I'll try filling it up completely. I've also found if you go by how full the holding tank looks through the bowl instead of the indicator on the front waste will seep out between the upper and lower tanks. Does your indicator in the little "window" still work? I haven't been able to see mine this season. Maybe it wont show until it gets somewhat full?