Backflow into Bowl

[Barrie McDonald]

While under way my on board head and holding tank is starting to backflow into my toilet bowel after the bowel has been pumped clear. What is causing this? I did close off my raw water inflow valve into the bowl but it hasen't made a differrence. The flip lever to fill-pumpout is in the correct position. I am at a loss. What do you think is the problem???Barrie Mcdonald

 

[Bob Faelten]

head details

I have had extensive experience with all systems aboard my 1982 O'Day 30, including the head and backflow problems.The first positive thing to do about it , is to install a 1 1/2" PVC ball valve on the discharge line before the high loop, then of coarse go into a high loop. (keep the valve closed when the boat is at its mooring and when not in use). Also the head, naturally, needs to be pumped out at the deck fitting or at sea , when full. I prefer the latter, do to the convenience. I have a wye valve right at the top of the loop where the flow can be deverted from the holding tank directly to sea. also I have tee'd off the pump out line to a "gusher pump" which goes to a "TY" to sea just below the wye valve. I hope this helps.

 

[Peggie Hall/Head Mistress]

More questions than answers

Is the water coming back into the bowl clean (flush water) or dirty (waste from the tank)? Does it happen all the time, or only when on one tack? Only when underway, or when the boat's at rest too?Does it happen when the tank is empty, or only when the tank has filled to a certain point?Do you have a thru-hull and pump to dump the tank at sea? Is the tank filling up too?What do you mean by "raw water inflow valve"--the seacock/thru-hull, or the valve on the toilet?

 

[John]

Some answers for the same problem

I have the same problem which reared (pardon the pun) it's head for the first time this weekend. My girlfriend left the pump in the wet position after use, and a few hours later while sailing, the whole toilet was full of dirty water from the holding tank. It is a small holing tank ( probably 12 - 15 gallons ), and had been used maybe 10 times over the weekend, so I'm assuming it was not full.I swithched to dry and pumped it all back into the holding tank, and no more problems.Not sure if it's on just one tack, but we were well heeled on multiple tacks all day before and after the problem.Is this like just because she left it on wet?? Doesn't seem too great a design. I just bought the boat, but the previous owner had no problems, and just replaced the holding tank and hoses maybe 2 years ago.Any advice on weather or not I have a problem and how to fix??Thanks.

 

[Peggie Hall/Head Mistress]

It doesn't make sense that leaving the dry/flush

lever set to flush would fill your bowl with waste from the tank. The dry/flush valve only opens and closes the intake...allowing flush water to come in or blocking it. So what was filling your bowl HAD to be flush water through the intake. 10 flushes in a 12-15 gallon holding tank would fill it at least 3/4 full, which would be enough to flow back into the head discharge hose when you're heeled. However, for enough backflow from the tank to flow into the bowl along with the flush water to make it dirty, the joker valve has to be long past the time it should have been replaced. But how could you not KNOW whether the tank is full??? Do you just keeping flushing and hoping for the best? Do you pay any attention to whether waste is spilling out the vent when the head is flushed??

 

[John]

I think I figured it out

I think she pumped only on wet only 3-4 pumps, so the waste never made it to the tank.As I had said, this is my first non porti-potti, so I did not know to look at the vent line. I have a semi-transparent tank, so I had checked that and the level seemed fine.