All of my travel trailers have had gravity-filled fresh water tanks, and it's always been a struggle to get the water in them. The fill port is on the side of the camper, so the water has to enter sideways while the air is trying to escape the same hole, since the vent is much smaller. So you have to reduce the flow, adding more time to the task.I've used an adapter hose that is readily available at camper-supply stores. It's maybe 6 inches long the goes into the fill hole. It helps a little, but not much. My current camper has a fairly long hose from the fill port to the tank, and the back pressure makes the adapter hose difficult to use.So I finally came up with this: Simply cut the end fitting off of a 4-foot (1.5 meter) garden hose and insert it into the fill port all the way to the bottom of the tank. Then you can turn on the water full-force and wait for the water to displace the air from the bottom-up. Filling the fresh water tank is a breeze now.

I've been using a cut off section of garden hose for years. Also, if you have an old water hose that connects to the back of your washing machine in your house, cut one end off. The hose is now a perfect size to shove up your water heater drain plug hole to rinse out the lime build-up. Why spend money for a plastic one at an RV store if you have something laying around the house that doesn't cost anything!

Doesn't air escape from your overflow outlet? Is your overflow outlet kinked or clogged? Never had that problem with any RV except an old 1960s TC that didn't have an overflow outlet.

Apparently not. I have a 1" hose into the tank and a 3/8" vent connected to a lockable fill port on the outside of my camper.

Blacklane wrote:Apparently not. I have a 1" hose into the tank and a 3/8" vent connected to a lockable fill port on the outside of my camper.Sounds like you have a blockage in the vent hose. The 3/8 hose is more than enough to pass the air out of the tank if functioning properly.

I made a hose from clear plastic food grade tubing that is about 4 feet long. I insert it all the way to the tank and fill away, just as you do. Works great, no splashback and much quicker. Why anyone would waste time doing anything else is beyond me. Happy Trails.

Filling the Fresh Water Like a Boss | Good Sam Community

maxum1989
Explorer II
Sep 30, 2014
Hands down. Blocked vent tube. This has happened to me many times. After I clear the blockage in the vent tube it seems to come back every year at least once. I have the same screen on my vent tube as well. So, when it does occur, I just take a small piece of clear tubing that fits right against the vent tube (on top of the screen) and put the other end of the tube in my mouth and blow. Now, I know that sounds a little odd, but it works. The difference is night and day. When blocked or partially blocked the water gurgles, makes a lot of noise and just struggles or doesn't fill the tank at all. When cleared, the air escaping can be heard quite clearly. I have gotten so used to it, clearing the vent line is something I do regularly when filling my tank. On mine, when I blow through the tube I can make it gurgle in the fresh water tank. That's when I know it has fully cleared. I have no idea what is causing the blockage but it has done it from the first year I owned my trailer.
Bucky_Badger
Explorer
Sep 19, 2014
Voyager Mike wrote:
This business of sticking a hose down into the tank when the vent pipe is blocked is scary. Fresh water tanks are NOT designed to take pressure, and will burst, usually right around the winterizing drain nipple on the tank.

Think about it... they put a 1/2 inch hose in a one inch opening... the air escapes between the two hoses
milo
Explorer II
Sep 18, 2014
Yeah well we never had a problem filling our tank with the gravity flow hole. But now that our new 5er doesn't have a gravity fill I had to do some white man engineering to figure out how to get water into the tank when we didn't have a water spigot available. Works like a charm.
Blacklane
Explorer
Sep 15, 2014
Blacklane wrote:
Original poster here.
For everyone who thinks I might have an insect or something in my vent opening, I don't see how, since it's covered with a screen (the small hole on the bottom right).

It's also obvious that I don't have a kink in either the fill line nor vent line. The biggest problem is that I have a long horizontal hose to my fresh water tank (the green/white hose).

A regular hose-end will only fit into the opening an inch or so, and when you turn on the water, it just splashes back unless you turn the volume down really low.

My solution is to insert a long fill hose (with no connector) into the fill port all the way to the bottom of the tank. Then I can turn on the water to maximum and the tank fills from the bottom up.
camperkilgore
Explorer
Sep 14, 2014
I'll bet that some sort of insect has built a nest in the vent tube. I put a screen over mine to stop this from happening.
Voyager_Mike
Explorer
Sep 14, 2014
This business of sticking a hose down into the tank when the vent pipe is blocked is scary. Fresh water tanks are NOT designed to take pressure, and will burst, usually right around the winterizing drain nipple on the tank.

I would suggest WITH THE INLET CAP OPEN, stick some air pressure (low air pressure) to the vent opening and see if you can clear the blockage. If not, because perhaps a kink has developed which you cannot get to, run a vent hose down the inlet.
Shadow_Grey
Explorer
Sep 12, 2014

We put a 5/8" hose end into our fill on the side and walk away until water runs out, it goes in maybe 3 inches, the vent works fine to get the air out.

This, except I let the DW do it so I don't get wet when full. :)
Bumpyroad
Explorer
Sep 12, 2014
sch911 wrote:

Not going to argue with you other than to point out the density of the air is much less that the water. Hence the smaller hose requirement for the vent. I'm done now...

seems to me that in portable gas cans, the "vent" opening is considerably smaller than the pour spout.
bumpy
sch911
Explorer
Sep 12, 2014
Blacklane wrote:
Not when you're filling the tank with a 5/8" hose. You must reduce the flow to less than a third, since the area of a 3/8" diameter hose is about 1/3 the area of a 5/8" hose. It's actually far less than that, since the air not flowing out of the vent is flowing against the water you're trying to put in.

sch911 wrote:
Blacklane wrote:
Apparently not. I have a 1" hose into the tank and a 3/8" vent connected to a lockable fill port on the outside of my camper.

Sounds like you have a blockage in the vent hose. The 3/8 hose is more than enough to pass the air out of the tank if functioning properly.

Not going to argue with you other than to point out the density of the air is much less that the water. Hence the smaller hose requirement for the vent. I'm done now...
mockturtle
Explorer II
Sep 12, 2014
Bumpyroad wrote:
I would recommend that if you use one of those commercial units with the foot long plastic tube and shut off valve that you silicone seal the tube to the fitting before you lose it down into the tank.
bumpy
I put a hose clamp on mine. I also extended the clear plastic hose with another foot or so of slightly narrower tubing.