Trojan Boat Forum

Should the sewage holding tank be vented, the reason i ask is when I flush the toilet, water is coming out a vent on the side of the boat, I thought the tank was full, had it pumped out yesterday but the owner of our marina said nothing came out of the tank.

Thanks Craig

Should the sewage holding tank be vented

Yes. The vent keeps the tank at atmospheric pressure as the contents enter and leave. The holding tank is not a pressure tank.

If you flush the toilet and water comes out of the vent, yet

nothing came out of the tank

when it was pumped, it sounds like the line between the tank and the pumpout fitting is clogged. Try adding water (slowly) to the deck pumpout fitting. If after a gallon or three it starts to back-up, the line between the fitting and the tank is obviously blocked with something.

You could also have the tank pumped again. While doing so, put your finger (briefly) over the vent as suction is applied to the deck fitting. You should feel suction on the vent if air is being drawn into to tank as the vacuum is applied to the deck fitting.

Is this the first pumpout this season? Does the blackwater discharge hose run continuously uphill from the tank to the deck fitting? Can you see the level of the contents in the tank?

If you boat in waters where overboard discharge is permitted, it is also possible that you have a Y-valve that diverts the goods to the tank or overboard and it is in the "overboard" position. A closed valve would sure cause a blockage.

Seriously? Is there a place in North America where you can discharge overboard? Even in the ocean don't you have to be a distance offshore. Just seems odd this day in age.

Yes, seriously. I didn't bother to look-up exactly where Orono is, but I know that Ontario fronts salt water on the north side, and the eastern-most portion of what fronts the St. Lawrence is about two days drive to the ocean -- a quite reasonable ride in a boat, and a distance that I have run several times.

Not being familiar with our friend's boat, I assumed the general case of what could be wrong. Boats occasionally move from one geographic location to another, say from a location where overboard discharge is permissible to one where it is not. It is perfectly reasonable to still have an overboard discharge in the U.S., all that is required to use it is that you need to be three miles offshore.

Thanks for the replie P-Dogg, now boys no need to get snotty, the boat has been in the kawartha lakes it's entire life, no overboard discharge allowed if I am checked and found to have this problem could be HUGE fines and also it is disgusting to put this crap in our lakes or oceans for that matter. I have looked for a valve to change from overboard discharge to holding tank, did not see one. I have a feeling P-Dogg maybe right clean out line may be blocked. On my F26 when the tank was full it never discharged through the air vent when the toilet was flushed, I will go up to the boat Thursday morning before my wife comes up Thursday evening for the weekend and try and solve this problem. Also the holding tank looks like it could be a tank for waste or a water tank for fresh water. I am quite sure this is not the original tank. I am hoping to simply reconnect the waste in, pump out line and air vent line, maybe a different configuration of lines connected will slove this problem.

Thanks Craig