Plugging 2nd vent

[stiltz49]

I have 2 vents on my fresh water tank. One under chassis suspect from top of tank. The other one is at the filler opening where I can pour in water. My question is may I plugged the one under the chassis? I loose plenty of water when drivng down the road. We do a lot of dry camping. I think the vent at the fill spout will do. Any ideas or suggestion welcome. I think I could hold more water if it was plugged because after I fill it and turn off the water it continues to drain. Thanks in advance..

["007"]

Welcome to irv2 stiltz49.
What if you do not fill to over flowing will the water still siphon out of tank while driving?
Do you also have a way to fill tank from water closet with a divert valve off your city water connection?
You will need a vent some place for air to escape or suffer the results.
Try plugging up each vent one at a time and see if you can fill tank without a problem.
Smaller vent may require longer time for fill up if valve off city water connection thus the larger vent is needed.
Let us know what you find. enjoy the forums.

[Cruzer]

I don't know that I'd rely on the upper fill fior adequate venting. If you fill the tank via the hose connection you could overpressurize the tank. I'd keep the lower vent. You'll need it if you ever overfill the water tank. I would simply modify it. Here's a shot of mine. It has a riser and an anti-siphon vacuum break valve to prevent draining the tank due to siphon action. there's a duckbill on the bottom to keep critters out. I fill the tank until water runs out then shut it off and no more dripping. I can carry the full 90 gallons without losing a drop.

[stiltz49]

I have a motor home so gaining access to the water tank is next impossible. Yes, usually fill with city water hose until it drains out lower veent hose. What I was thinking is plugging the lower vent and opening the graacity feed cap when filling and then I think the vent at the graity fill will be ok for using the water. Any thoughts and also Thanks again for the information given...

["007"]

Like I said plug up one of the vents and see how it fills than swap vents and see how it fills with that one. Just make sure you have one of the vents open.
Let us know what happens.