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How Can I Stop The Fresh Water Tank On My Motorhome From Leaking?

by Daniel Deveau
(Cyr Plantation, Maine)

I purchased a 1996 Catalina Coachman Class C tandem axle motorhome on last week. The previous owner stated everything works. I later found out the motorhome has been idle for 6 years. As I am filling the water supply with a garden hose on the water supply inlet it approached 80% fill capacity it started leaking.

Do I have to remove siding or whatever to access the fresh water tank to investigate where these leaks are coming from? I have looked everywhere and cannot find diagrams to assist me.

Thank you


ANSWER: Greetings Danny thanks for submitting your question on our Ask An RV Question Page.

I believe based on what you are saying that there is not a problem with your fresh water holding tank. I believe that the problem you have is with the water level sensor in your RV's fresh water holding tank. Holding tank gauges and sensors on RVs are notorious for giving inaccurate readings.

Even though the gauge is showing that the tank is only at 80% capacity I believe that indeed the tank is actually at a 100%. When a fresh water tank is filled up above 100% it is designed to leak out the excess water. So in my opinion you do not have to take out your fresh water tank as there is no problem with it.

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If I were you I would not even go to the trouble or expense of replacing the fresh water level sensor or gauge. Just remember that when the gauge reads 80% that it is actually at 100%. Or you can do what most RVers do (including myself) and fill up your fresh water tank until water starts coming out and then you will know it is full.

I hope that this information is helpful to you and I also hope that you enjoy your new RV.

Happy RVing

RVing Al
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Comments for How Can I Stop The Fresh Water Tank On My Motorhome From Leaking?

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freshwater tank
by: Gidgit

I have a 97 Sierra camper I have not put fresh water in my holding tank and its leaking I have city water running through the other line so why do you think its leaking because I have not put any water in it

water pump leak
by: corey

i have a 1993 catalina coachmen and when i use the water pump, water leaks out in the left rear near where the pump is located, it gets the carpet wet on the inside and drips on the outside. what i want to know is how do i access the pump i can't seem to locate it and don't see any hatches to access it. I'm sure its a simple problem like a loose connection how ever i just don't know how to get to the darn thing to inspect it.

city water and fresh water
by: Joe c

I have a problem putting water into fresh water tank. Also city water stops running at times then will start back a little later.

Leaks in RV tank for fittings
by: Anonymous

If your tank is make of High-density polyethylene and actually has a leak, this may be fixed with a pencil torch and (High Density Polyethylene (HDPE) rods. (Approx 1/8" dia x 12" long) These rods are used to fix canoes made of HDPE. I fixed two leaks on a Coachman Class A Motor Home fresh water tank using these rods. Worked well.

Water tank fill problems
by: Don H.

I have a Next level 5th wheel 2005 and i have a new problem. When i fill my tanks with fresh water it will start to leak out of the overflow and i turn off the water but it keeps leaking out the over flow. it is syphoning out the tank down to 1/4 tank. I needed the water for a trip so i put a 1/2" plug on the pipe and i could use a full tank of water. I don't know why it is syphoning out all of a sudden. Any ideas? Thanks Don.

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