# Clearing the Holding Tank Vent Hose



## brucemoody (Jul 2, 2011)

Recently purchased a Hans Christian 33. We're dealing with foul odor from the head and going after all variables in play. We bought the boat from a person who spent weekends aboard it but never took it out to sail. When we took ownership of the boat, her holding tank was completely full. The macerator wasn't wired for power. Consequently, flushing the toilet would force effluent through the vent hose and out those nozzles on the starboard bow. That's great for crowd control but not so much when trying to make a good impression at a new marina. The macerator is now wired and working like a champ, we've emptied the holding tank and flushed it with water and a bottle of treatment. Still, I am certain those vent hoses are jammed and not allowing air to pass. Any ideas of how to clear the vents? Thanks!


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## tempest (Feb 12, 2007)

How difficult would it be to just replace them? Mine is pretty accessible..I'm not familiar with how yours are run.


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## Donna_F (Nov 7, 2005)

Congrats on your new boat!

I don't know how your hose is configured, but ours exits the boat and runs into a stanchion. We disconnected the hose on the inside and forced water through it. Worked great.

Additionally, even if you clear the gunk out that created the clog, something will still stick to the sides. As long as the hose is dirty you might have an odor. That goes for any hose on your boat. You might want to think about removing and replacing them all.


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## sea_hunter (Jul 26, 2000)

Try putting the fw hose over the vent cover while you're pumping out. Sometimes when the boats been sitting it doing a crossing with full tanks it backs into the vent or a bug has made a home in the vent. Backflushing it will usually clear it if plugged.


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## CapnBones (Sep 20, 2010)

Replacing old hoses is always the best... That being said, when I pump out if I think my vent hose is clogged and sometimes just for good measure I put the freshwater hose up to the vent and blow water in while the vacuum from the pump helps pull and it clears out nicely. As sea hunter said.


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## Minnewaska (Feb 21, 2010)

Our vent line exits the side of the boat. However, from the inside, you can see that it makes a loop up by the decks and then returns down to the fitting. I'm sure this is for anti-siphon. However, simply directing a hose spray from the outside, is not likely to make it to our tank. If I were to force the hose into the fitting, it would pressurize the tank, as the displaced air would have nowhere to go. The vent is blocked! Even opening the pumpout fitting may not work, as the intake is likely below the tank contents, so air will not escape. Be careful.


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## sea_hunter (Jul 26, 2000)

Replacing the hoses is a lot of work especially when not required; the tank vents from the top NOT the bottom, flushing some water through it may be all it needs. Stop looking for the hard when easy is mostly best.


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## CapnBones (Sep 20, 2010)

Minnewaska said:


> Our vent line exits the side of the boat. However, from the inside, you can see that it makes a loop up by the decks and then returns down to the fitting. I'm sure this is for anti-siphon. However, simply directing a hose spray from the outside, is not likely to make it to our tank. If I were to force the hose into the fitting, it would pressurize the tank, as the displaced air would have nowhere to go. The vent is blocked! Even opening the pumpout fitting may not work, as the intake is likely below the tank contents, so air will not escape. Be careful.


Like I said, while drawing a vacuum with the pump out, spray the water. This not only forces the water in (pressure of the hose) but it should be drawing air in through the vent (or trying to anyway). My vent is on the side of my hull as well and it fixed my clog like a champ.


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## MarkSF (Feb 21, 2011)

brucemoody said:


> Recently purchased a Hans Christian 33. We're dealing with foul odor from the head and going after all variables in play. We bought the boat from a person who spent weekends aboard it but never took it out to sail. When we took ownership of the boat, her holding tank was completely full. The macerator wasn't wired for power. Consequently, flushing the toilet would force effluent through the vent hose and out those nozzles on the starboard bow. That's great for crowd control but not so much when trying to make a good impression at a new marina. The macerator is now wired and working like a champ, we've emptied the holding tank and flushed it with water and a bottle of treatment. Still, I am certain those vent hoses are jammed and not allowing air to pass. Any ideas of how to clear the vents? Thanks!


Are you aware it's illegal to empty the holding tank in coastal or internal waters, macerator or not? Please use pumpout facilities.


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## Minnewaska (Feb 21, 2010)

CapnBones said:


> Like I said, while drawing a vacuum with the pump out, spray the water. This not only forces the water in (pressure of the hose) but it should be drawing air in through the vent (or trying to anyway). My vent is on the side of my hull as well and it fixed my clog like a champ.


I wasn't disputing your advice. But you have made me think of whether the input from the hose would match the suction from the pump out. Probably not. In this case, I suspect a vacuum might be created in the tank.


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## sea_hunter (Jul 26, 2000)

Minnewaska:909573 said:


> I wasn't disputing your advice. But you have made me think of whether the input from the hose would match the suction from the pump out. Probably not. In this case, I suspect a vacuum might be created in the tank.


Like I said, it works just fine. Just make sure you're doing it to the holding tank vent and not the fuel vent.


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