Wednesday, November 29, 2023


I have trouble filling RV’s fresh water tank. What’s the solution?

Dear Dave,
I regularly have trouble filling my RV’s fresh water tank. I have a 2018 Rockwood Windjammer TT. When filling the tank, the water starts to come back out the filler tube, and when I check the panel, it’s says 1/3 to 2/3. I have tried to turn on the pump, open a faucet, rock the trailer, fill slowly (as recommended by others on FB).

The last couple times I shot compressed air bursts down the vent tube (right next to the filler tube). I almost immediately have water shooting back out the vent tube. Then I hear air coming out the vent tube. When it stops, I start filling again and am able to get several more minutes of filling time and the trailer panel will flash full or the light stays on full. I thought I’d run a stiffer tubing inside the vent tube to clear any obstruction, but I’m not sure that’s the solution. From what I see online this is a fairly common problem. Any help would be appreciated. Thank you. —Dave, 2018 Rockwood Windjammer

Dear Dave,
I wouldn’t say it is a common problem as I have not gotten a question regarding trouble filling an RV’s fresh water tank in several years, although I have come across this problem myself. One time it was a kink in the supply hose that restricted water flowing into the tank when the water source had high pressure. I tried running a fish line down the tube as well as different descaling solutions, but it continued.

Bent supply tube

What I eventually found was a slight kink that got worse as the weight of water came into the supply tube and bent it even further. I replaced the tube, which was not an easy task, and installed a spring “bend” protector to keep it from kinking again at a point in the tube where it started to bend slightly.

If your supply tube does not go straight to the tank, but rather bends upward or even goes below the tank then up, it would be best to remove the fill port and shorten the tube so it goes straight to the tank, with no bends or dips.

In another situation it was the vent tube not being large enough to allow air to escape the tank as I filled it up. Since you shot compressed air down the tube, I would assume it is not plugged but could be kinked or just not large enough to allow air to flow. However, if you get several minutes of filling after the compressed air bleeds out, it does point to a possible kink in the vent hose. Most of these hoses are just a cheap 1/4” hose that is flimsy. I would recommend replacing it with a stiffer hose.

Since your rig is a travel trailer, hopefully the water tank is accessible under the dinette seat and you can get at either the fill tube or the vent tube.

 You might also enjoy this from Dave 

Beware damaging your RV with high water pressure in campgrounds

Dear Dave,
“I just bought my first RV, a Keystone Springdale travel trailer. I’m concerned about the water pressure at campgrounds. I’ve heard horror stories that too much pressure can damage the water system. Are there ways I can keep that from happening? Do I need to be concerned?”Lana

Watch the video for Dave’s answer.

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

Read more from Dave here


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Dave Solberg
Dave Solberg
Dave Solberg is a leading expert in the RV industry and author of the “RV Handbook” as well as the Managing Editor of the RV Repair Club. He has been in the RV Industry since 1983 and conducts over 15 seminars at RV shows throughout the country.



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Neal Davis (@guest_243628)
4 months ago

Thank you, Dave! Always helpful advice. I can use it now, in the future, or share it with others even if it does not apply to my rig at that time. Thank you for such careful and complete answers. 🙂

Wayne (@guest_243235)
4 months ago

Our 09 Cedar Creek had the same issue. The fill pipe went up and down over several crossmembers because the tank is about 10 feet from the filling cap.
going over a crossmember also cracked the hose.
I removed the belly covers.
Replaced the hose with a better one. I also then managed to fasten a 2 inch piece of aluminum angle to fasten the hose to.
Having the angle higher at the end closest to the fill cap so it is one long grade to the tank with no low points.
Since I had the belly off I also cut off the vent line and turned it straight down through the belly so it is only about 15 inches long.
Now when the tank is full I can see it draining right away.

Michael (@guest_242726)
5 months ago

I have a Leprechaun 311. There is a shutoff valve right before the tank. There is a drain valve in the fill line right before the shutoff valve. Both valves must be set properly before you can use the tank. The previous owner never used the tank because they could never fill it. Is the shutoff valve common?

Phil (@guest_242721)
5 months ago

I have a 2001 Komfort 5th wheel. The fill hose runs almost level and only had one support in the middle. Water would collect in the dips in other areas. I made up a new fill hose with a female hose end and a long vinyl hose that reached all the way to the fresh water tank so the water goes directly into the tank without getting blocked by the dips. Full flow of water and no backing up until the tank is completely full. Parts are available at big box stores or any good hardware store. Simple fix and easy to make.

R.C. (@guest_242706)
5 months ago

(Continuing from my comment where I used too many bytes :):
I know enough from me having to do everything on my RV that I could be a Mobile RV mechanic but, can’t afford the high cost of training to get “certified”.

R.C. (@guest_242705)
5 months ago

Finally, an article in this. I wrote about 3 years ago and never got so much as a reply. Maybe, I have to pay to get a response. 🤔
I have been battling this EXACT same problem since buying our 2019 Fleetwood Flair 29M.
Craftsmanship doesn’t really exist in these RV’s. Nevertheless: I have done the exact same thing by using a small blower to blow into the full port and it would spit water back out. Then, I could fill. I used to have to do this 3 to 5 times before I would have a full tank. Now, sometimes I only have to do it once maybe twice. I opened up the storage under the bed to get to all the tubes for water tank( you know.., where all the electrical is), some lines were left with several bends and some that were routed in a way it looks like a jigsaw puzzle. One thing I did notice is that it seems like a small vent line so, I’ll tear the house apart again, and look into that. Needless to say, due to quality and craftsmanship put into this rig…, I know this RV VERY WELL!!

Diane McGovern
5 months ago
Reply to  R.C.

Hi, R.C. No, you don’t have to “pay to get a response.” We try to reply to questions from everyone, contributor or not. I looked back through your 28 comments since 2021, and don’t see anything regarding fresh water tanks, so I’m not sure where that comment went that you’re referring to. Sorry. Have a great day. 😀 –Diane at

Dan (@guest_242690)
5 months ago

Sounds like another great design assembled by people who take great pride in their work, from an industry known for their great quality. Ain’t it great?

Mel (@guest_242696)
5 months ago
Reply to  Dan

It’s all done by low paid amateurs with little experience or no training. Yet we’re expected to pay high dollar for their “high quality” craftsmanship

R.C. (@guest_242704)
5 months ago
Reply to  Dan

Funny 😆

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