How to unclog the fresh water vent

[Capt’nKarl]

Each time I’d fill our fresh water tank no water would come out the vent tube. Not a big deal but I wanted to make sure the vent was open. The tank would fill and overflow but nothing came out the vent. Here’s what I did. I bought a regular rubber plunger suction cup, removed the handle and drilled a 1-2 mm hole in the rubber cup where the wooden rod screwed in. The hole I drilled was just the size of the compressed air attachment used to spray off dust and such. With the water tank empty and all the faucets closed I opened the fresh water fill and placed a small piece of tissue paper under the cap but over the fill hole. I did this so I could visualize any movement of the tissue when pressure was applied. Once all this was done and the air compressor tank full I placed the rubber cup over the vent opening, placed the spray attachment so the air would be forced into the hole and pressed the lever. Air was forced through the vent opening and I immediately heard a slight pop and saw the tissue paper flutter. I repeated this process a couple of times then filled the water tank and Voila water came out the vent. Pictures of the apparatus in my album. I feel victorious!

 

[SJI Sailor]

Great idea! I have been wondering about this.

BTW I use a round fireman's hose nozzle to do something similar for the holding tank vent -- but that uses water and of course didn't want to do that with the same nozzle for the water tank. Air is better, I think!

 

[GaylesFaerie]

When you mentioned the plunger I thought you were going to place it over the vent hole in a compressed state and pull to draw the blockage out. Is it possible that pop was some gunk being forced back into the fill pipe / tank? GF

 

[Capt’nKarl]

I don’t know what made the pop sound but it was something blocking the vent tube. Whatever it was it is now inside the fresh water tank so I’ll have to wait and see if anything happens. We only use the water to shower off, rinse dishes and flush the head. So far the taps are working fine. Time will tell. I used this method to clear the vent because getting to the water tank is nearly impossible.
Thanks,
Karl