Water keeps draining out of the overflow

bdpreece wrote:
Unfortunately on many rv's the overflow is plumbed in such a way that once it starts to drain for any reason such as sloshing as you go around a corner, it creates a vacuum and can empty the entire tank.

YES. IF the water really IS coming out a vent/overflow line.

My vent/overflow is a little hole right next to the filler neck.

Mine also has a quick drain valve in the bottom of the tank which also could be the culprit here too.

bdpreece wrote:
Unfortunately on many rv's the overflow is plumbed in such a way that once it starts to drain for any reason such as sloshing as you go around a corner, it creates a vacuum and can empty the entire tank. For now your best bet is to plug the drain but don't forget to remove the plug when filling the tank. The correct fix is to find the overflow line and loop it upwards above the tank then down.

What bdpreece said ^^^^
This is a very common issue. I see trailers(including mine) and 5vers mostly doing it while driving down the highway. I suspect because there is little clearance between the top of the tank and the floor above it. Definitely search for the low point drain shutoff first. However, if it turns out to be the vent valves one common solution is to put shutoff valves on the tubes. Then close the valves while traveling. Leave them open the rest of the time.

I'll offer this has a suggestion. Look on the inside trailer floor directly above where the water is draining. Look for a cutout in the floor and left in place so it's not very noticeable. (in my trailer it's a 5 inch circle with a small hole for my finger to lift up the floor cutout).

Yes, the tank drain valve. That's what I'm trying to find. I've looked at the paper manual, and the online PDF manual, but the only mention they have for the drain (even after text searching the whole document) is:

1. Drain the fresh water tank.

Nothing about how that's supposed to happen, or where the actual valve is :/

Make sure that the tank drain valve is closed.

I'm thinking what you see is the low point drain not a tank overflow. There will be a shutoff valve for the low point drain and the location should be in your manual in the section how to winterize your fresh water system.

Unfortunately on many rv's the overflow is plumbed in such a way that once it starts to drain for any reason such as sloshing as you go around a corner, it creates a vacuum and can empty the entire tank. For now your best bet is to plug the drain but don't forget to remove the plug when filling the tank. The correct fix is to find the overflow line and loop it upwards above the tank then down.