Fresh water tank: Leaking from the top while in motion

I've checked other past threads on this subject, and have not found a post where the fresh water tanks was leaking while the trailer was in motion. Issue: the fresh water tank on my 2016 Landmark Newport is leaking from the top while i am in motion (driving it down the road). I've pulled down the coroplast and checked both (left and right side) overflow valve connections and the fresh water tank drain line connections. None of the three have leaks where they are connected to the tank. I am wondering if there is another area on the top (maybe a vent line) or something i need to check. Wondering if anyone has experience in this area you dont mind sharing. Also, is there a vent tube or something else on the top of the fresh water tank i need to check?I am currently using a fan to dry the insulation. Thanks and appreciate any feedback.

Do you mean the leaking water going into the underbelly? Or is it just that you're losing water while towing?

Yes Dan. Water leaks (from some place on the top) into the underbelly, and only while the trailer is in motion. The fresh water tank is currently full. Excess water (while filling) drains properly out of the two overflow valves.

Here's a photo from 2015. I think you've checked the 3 connections to the tank. There are no others I know about.
Given that the overflows on each side are near the top of the tank, it could be difficult to give it a close inspection from underneath.

Are you certain the leak is coming from the top. It looks like you have YETI package tank heating pads. It's possible it could be leaking from above the pad. If you have that, try pressing on the pad to see if you can squeeze water out.

Thanks for the information Dan. I checked around the yeti pad. I cannot see any leakage around that area. The other possibility is the input water line connection to the tank. i need to cut under the rear IS axle to see that area. Thanks again.

I had a crack near the top of my black water tank that leak. Tank was replace.

Mine was doing the same thing only because I had more water in it than I usually travel with. My wife was following me and said water was coming out from both sides of the trailer. I took the coroplast down and the insulation was wet. Pulled the wet stuff out and could not find any leaks anywhere. I put a length of plastic tubing on each overflow fitting extending it down below the frame. I'll check it tomorrow and see if it's wet again but I didn't notice any drips today on the road. I checked it again today, Friday and found no evidence of water leakage anywhere!


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Thanks Jim. Can you share the size & dimensions of the plastic tubing you used?

I checked all the connections to the fresh water tank, and all looks well. I dryed up the insulation and put it back together this morning. I look forward to hearing back on the plastic tubing. Hopefully it will help me out as well.

Mike

It's clear plastic tubing I got at Lowe's, 1/2" I.D. I'll take a pic in the morning and post it.


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I have a one year old Bighorn. I filled the fresh water tank up to the over-flows and then start my voyage. Approx. 200 miles of up and down highway driving I found that I had lost about 1/3 of the tank. The only place where I think I lost it was from the over-flows. Can I plug up the over-flows while in motion or will that be harmful to the tank?

chris

We have a 2019 bighorn 3270 that when traveling with more then 1/3 of a tank it leaks out what looks like the street side over flow. I have had it 2 times to dealer and not fixed yet. I have heard that some trailers have 2 water tanks how do you find out other then taking down under belly? or is a valve on over flow the only fix.

Love this trailer and we do dry camping and it would be nice if we have a full tank of water.

Dave

Water sloshes around the tank as you go down the road, and is forced out the overflow.

Some people have put cutoff valves on the overflow. But you MUST remember to open the valve when filling the tank. With pressurized water filling the tank, if there's no overflow, it's possible to damage the tank by overfilling.

I haven't heard of anyone trying this, but if you attached a water balloon to the overflow fitting, that might keep the water in. And if you forgot to remove it, the balloon would likely break before the tank did.

If you try the balloon, let us know how it works.