Can rough roads create a suction from the water tank vent?

[Pangaea_Ron]

I have been driving some windy and hilly roads on Highway 101 on the Oregon Coast with the MH, and it seems that I have lost water from the water tank. Can surging water in the tank leak out the vent tube and create a suction that would drain water from the tank? It seems to do that if I overfill the tank?

I noticed that a bit of water was dripping out the vent tube when I stopped at a view point.

[rockhillmanor]

If I fill my tank all the way to where it comes gushing out the fill opening, yes when I hit the road it sloshes around and comes out the overfill and down the side of the RV.

I make a point of NOT doing this anymore because of the concern of other people/cops when you pull in to fuel up and they see something dripping from the MH and need to point it out to you and ask concerning questions. :R

[Pangaea_Ron]

Thanks all for the responses.

I think that I can visualize water sloshing out, but probably not siphoning... although some of those corners were pretty impressive just south of Yachats. My wife gave me a side glance or two.

I like the idea of a plug or valve in the vent tube while underway. Are there any issues with pressurization while using the pump?

[BruceMc]

The vent tube is connected to a nipple at the top of the tank - no way it could suction the water out, but it is an outlet for sloshed water. I have a tapered plastic plug I use to plug ours while underway. We still have some loss as the fill is a couple inches higher than the top of the tank, and the fill cap doesn't seal very well.

Could be what you are experiencing on rough & curvy roads too.

[Beartoo]

I installed a valve to close the over flow after I fill the tank.

[Mandalay_Parr]

I suppose it could. Mine will siphon out a little if I fill it too full.