Fresh water tank leak? Need temp fix in the next 48 hours.

[inverseParanoid]

Just de-winterized yesterday and there is a very noticeable drip coming from the undercarriage, I'd estimate it at dripping 10-20 gallons a day. I turned the water pump off and ran all the lines, and the leak was still going just as fast 30 minutes later, so I think it's the tank itself leaking and not the lines.

When winterizing I pumped RV antifreeze thoughout the lines but merely empty the fresh water tank and left the drain valve open because people recommended not putting antifreeze in there and instead bypassing it by hooking up to the pump directly, so I guess it makes sense that there might have been some water left at the bottom that maybe froze and unfroze a bunch of times over the winter and ended up causing damage.

Some friends are picking it up Wednesday afternoon and taking it 5.5 hours away for 5 days. I'm pretty sure I can get the tank out this afternoon and my tentative plan is to use Marine Goop to seal the leak, wherever it is. (We never drink the RV water and we always tell people to drink bottled water instead when they use it without us.) I don't need to stop the leak completely (though that would be nice), but currently the leak is bad enough that you'd have to refill it everyday if your site doesn't have running water.

Does anyone have a better idea for how to quickly fix this, or see any errors in my logic?

Thanks,

Josh

[Ronhoward]

My fresh water tank is leaking out of the fitting on the side of the tank that goes to the vent. I can see where it has pulled loose from tank.You might look there

[Bordercollie]

I have seen a long wood screw that went into a tank due to a careless factory assembler. You will probably need to take rig into a repair shop with a lift that can drop the tank and fix the leak properly. Temporarily live with the leak and keep re-filling or use RV camp water supply.

[bob213]

If it does turn out to be a crack I've been told this works well. You will need room to get a torch close to the crack to warm it up a little.
Poly Weld

Hopefully you won't need this.

[dewey02]

I had a similar leak on my FW tank. I have two 40 gallon FW tanks that are connected by "equalizing" hoses. The leak turned out to be simply a loosened hose clamp on one of the 1" equalizing hoses. Just a few turns of the screw on the hose clamp and the leak was fixed.

I think you need to really take a good look at your tanks before assuming something is wrong with the tank itself. While that may be true, a loose fitting is a much more likely suspect. As others have said it is highly doubtful that the small amount of water left in the tank to freeze overwinter would cause a crack in your FW tank.

[PSW]

Could you just drill out the screws and then replace them with a size or two larger? That is a quick fix and works great if it is a Phillips type screw because the drill bit won't wobble as much. OR, can you take a pair of vice grips and grab the head of the screw, assuming it is not recessed? It is difficult to picture the exact nature of the support but if they are badly stripped, I have even resorted to the tried and true of just prying a bracket apart with a large screw driver.

It truly sounds like you are going to have to drop the tank to fix the problem because you have eliminated every other possible source of the fluid. If the fluid starts leaking when you fill it only an inch or two, I bet it had more water in it over the winter than perhaps you thought and just froze laterally enough to crack the tank.

Most of us including yours truly have had naughty winterizing experiences at one time or another. I am a little paranoid and I drain my lines and tanks, then I blow them out, then I fill them with about three times as much antifreeze as most suggest. My theory is that rv antifreeze is cheap and for ten bucks extra I can just feel better about it. I won't bore you with how I came to that conclusion on my first motorhome a long time ago. But it wasn't very pretty!!!

Good luck,

Paul

[inverseParanoid]

Hey Paul, the line between the tank and the pump is about 8 inches and I can see all of it and it is definitely not the Source of the leak. As for locating the leak, the water drips down through a crack between the fresh water tank and a "storage tunnel" (it runs the width of the RV and is not leaking into the storage area, merely around it).

The tank is about 40 gallons and my two ways of seeing it is by looking through a small 1x1' door in the back that reveals the water pump and all the connections to the tank, and then from above after unscrewing the board that mattress rests on. The leak appears to be coming from the back side (adjacent to the storage tunnel) which I cannot see, I only know that it starts leaking once it reaches a height of about 2-3 inches when filling the fresh tank, and appears to emanate from the left side of the tank. I've tried removing the tank so that I can investigate further but there is a bracket pinning it against the storage tunnel, and I can't seem to get enough leverage to remove the screws from the bracket in the tiny space that I have to work with.

When the pump is on and water is running the tank gets a little wet at the bottom, but mostly just falls through the crack between the tank and the storage tunnel. The same thing happens when the pump is off. I had my girlfriend try all the water sources while I was looking under the RV and none of them caused an increase or decrease in apparent leakage.

The screws to the bracket to remove the tank are slightly stripped and hard to access. Do you think spraying WD-40 on them would make it easier for me to possibly unscrew them? At this point I'm hesitant to move forward as I don't want to bite off more than I can chew, but everything else is disconnected from tank so if I could remove that bracket I think I could get the tank out, and once it's out I'm very confident I can temp fix it.

[PSW]

OK. From your posts you have determined that there is no leak when hooked up to hose supplied water. Is that correct?

Therefore, the leak is coming from the fresh water tank. That seems logical, but it could also be coming in the connections from the tank to the pump. It is very possible that when you didn't put antifreeze in the tank for the winter, some water was in the line between the tank and the pump.

Did you do what DrewE suggested above? Here is what he said:

If you leave the pump on with the taps all closed, does it cycle periodically? If it does, that's a good indication that the leak is in the pressure part of the system. If it doesn't cycle, then the leak/drip must be before the pump.


If the pump is not cycling with the pump on, but water is still dripping then it is from the tank.

I am mystified as to why you cannot see or find the source of the water you are seeing. If it is coming from the tank and the pump is not cycling, then obviously it is most probably a leak in the tank itself. You should see it running down the side of the tank or spot it from the bottom.

I don't understand why you can't park it on concrete, look at the drip and follow it around to see where it is originating. I would take a good flashlight, get under the chassis and watch the drip and see where it is from.

You need to carefully look at the line from the tank to the pump, and with the pump on observe the whole thing for the source. The amount of water you are suggesting of 10-20 gallons a day equates to a half a gallon or so an hour and that is a lot of water.....a pint every fifteen minutes. You should be able to find that much water and where it is coming from.

Paul

[inverseParanoid]

I ran city water and there was no leak. Then I filled the fresh water tank and it started leaking. The water tank has a release valve that's fairly obvious and is not leaking. I have no idea if there's some other low point that I can't see, but I've looked and looked over the past two years and have never seen one.

I can't identify the exact source of the leak, I just know it's emanating from the fresh water tank area, and I can't seem to be able to remove the tank on my own to investigate it (anyone know how? Can't find a single YouTube video or article that explains how to remove it, only articles/videos on how to fix it once it's out.) If anyone has any ideas of something I can try, I'm all ears. Otherwise there will be a leak for this 5 day trip and I'll have to see if I can get professionals to look at it if the RV repair places aren't already booked up.

[Bordercollie]

Did you actually verify that the low point drain valves are fully closed? If one or both are open partially or not shutting off , water will dribble out the bottom of your rig wherever your low point drain valves are located. Our low point drain valves are located behind a panel in the bathroom wall , hard to see hard to open, harder to close completely. If the valves are not closed, fresh water pump will cycle on and off or stay running.

[inverseParanoid]

I emptied the tank and I am going to hook the RV up to city water and run it through the lines. If it starts leaking then I know it's somewhere in the lines. If it doesn't leak then I'll fill up the tank again and see if that causes leak. Thanks for your advice everyone.

[pianotuna]

Eterbond can be used. They have a video "how to" on their website.

But--find the leak first!

[cyntdon2010]

I would find the leak before assuming fixes.

x2

[korbe]

As far as removing all the water from the tank, I park my rig on a side slope to the curb to get out much more water since my drain valve is located along the side of the tank near the bottom. I will then run my pump until it stops spitting water - only air. Then I will use the pink stuff.

I would find the leak before assuming fixes.

[DrewE]

Before doing anything too crazy, I'd double-check that the low point drain valves and the tank drain valve are all fully closed and don't have some bit of grit or something stuck in them.

I rather doubt that any slight bit of water remaining in the tank would cause it to crack or otherwise leak. There's plenty of room (horizontally and vertically) for expansion.

If you leave the pump on with the taps all closed, does it cycle periodically? If it does, that's a good indication that the leak is in the pressure part of the system. If it doesn't cycle, then the leak/drip must be before the pump.