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Old 10-14-2020, 03:41 PM   #1
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Fresh Water Overflow problem

I have a problem with my fresh water tank, when it is full the water starts to runout of the overflow hose and won't stop running. I end up with only 1/3 of water as per the gauge. Any suggestions????
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Old 10-14-2020, 11:18 PM   #2
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We do some dry camping and need all the water we can carry, I waited till water was coming out the over flow, shut off the fill, then shoved a bolt up the over flow, use some water then remove bolt. I replaced the bolt with a shut off valve. You have to remember to open the valve after a shower or some water usage. We were at a Goshen rally and I asked Forest River to check tank. Said everything was fine, they replaced my bolt with a shut off valve.
Hope this helps.
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Old 10-15-2020, 12:11 PM   #3
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Originally Posted by SilverbackTom View Post
I have a problem with my fresh water tank, when it is full the water starts to runout of the overflow hose and won't stop running. I end up with only 1/3 of water as per the gauge. Any suggestions????
I have exactly the same issue with my 33ik. I am having a shut off value installed and hopefully help with the issue. I have read other threads that suggest that there is no need to open the value until you are ready to re-fill the tank. So... I am wondering who is correct on the issue of having to open the value after using a bit of water or just keeping it closed? What function does the vent line play after filling the tank?

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Old 10-15-2020, 12:41 PM   #4
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Originally Posted by dcrajr View Post
I have exactly the same issue with my 33ik. I am having a shut off value installed and hopefully help with the issue. I have read other threads that suggest that there is no need to open the value until you are ready to re-fill the tank. So... I am wondering who is correct on the issue of having to open the value after using a bit of water or just keeping it closed? What function does the vent line play after filling the tank?

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It allows water to be used from the tank without sucking the tank sides in.... IF...IF... the system doesn't have some other method of venting. (like a hole in the fill cap for instance)

Every fresh water tank system and fill method is somewhat different. Not only in the physical parts but also in how well (or not) they are plumbed.
Some units seem to siphon out the vent hose where others don't when plumbed similarly.

The vent serves TWO purposes... it allows the air to escape the tank when filling while also allowing water out of the tank once full. This is especially important on R/Vs that use the city water hose to fill the tank as opposed to a gravity fill where some air can escape via the gravity fill tube. Without an overflow, you could possibly fill the tank until it exploded or (as we have had reports of) it will bulge the tank and bust the floor or the tank supports. It is never a good idea to "blast' water into the tank faster than the air/water can escape out the vent.

Secondly, the vent allows the water to be used out of the tank and allows atmosphere (air) back in the tank so there isn't a vacuum sucking the sides of the tank in as the water is removed.

Both of these scenarios require everything to work correctly and most times because of poor routing, kinks or poor connections, none of it works quite the way it should.
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Old 10-15-2020, 01:12 PM   #5
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Quote:
Originally Posted by lowbubba View Post
We do some dry camping and need all the water we can carry, I waited till water was coming out the over flow, shut off the fill, then shoved a bolt up the over flow, use some water then remove bolt. I replaced the bolt with a shut off valve. You have to remember to open the valve after a shower or some water usage. We were at a Goshen rally and I asked Forest River to check tank. Said everything was fine, they replaced my bolt with a shut off valve.
Hope this helps.

If you happen to forget to remove the bolt or open the shutoff valve is there a possibility of collapsing you holding due to the vacuum you will create?


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Old 10-15-2020, 01:23 PM   #6
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Originally Posted by 5picker View Post
It allows water to be used from the tank without sucking the tank sides in.... IF...IF... the system doesn't have some other method of venting. (like a hole in the fill cap for instance)

Every fresh water tank system and fill method is somewhat different. Not only in the physical parts but also in how well (or not) they are plumbed.
Some units seem to siphon out the vent hose where others don't when plumbed similarly.

The vent serves TWO purposes... it allows the air to escape the tank when filling while also allowing water out of the tank once full. This is especially important on R/Vs that use the city water hose to fill the tank as opposed to a gravity fill where some air can escape via the gravity fill tube. Without an overflow, you could possibly fill the tank until it exploded or (as we have had reports of) it will bulge the tank and bust the floor or the tank supports. It is never a good idea to "blast' water into the tank faster than the air/water can escape out the vent.

Secondly, the vent allows the water to be used out of the tank and allows atmosphere (air) back in the tank so there isn't a vacuum sucking the sides of the tank in as the water is removed.

Both of these scenarios require everything to work correctly and most times because of poor routing, kinks or poor connections, none of it works quite the way it should.
Thank you... good to know!
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Old 10-15-2020, 03:09 PM   #7
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Smile Legacy Driver

It sounds silly but my overflow hose is long enough that I can lay under the coach and blow in the hose to break the siphon and the water stops overflowing. No valve to forget.
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Old 10-15-2020, 05:45 PM   #8
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If you can get to the top of the water tank, simply drill and 1/8th inch hole at the top of the loop in the overflow where it leaves the tank. Cheap and easy - and you don't have to shimmy under the coach.
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Old 10-16-2020, 06:32 AM   #9
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Just to add, my gauge, like most, doesn't reflect when the tank was filled. Used to fill until it came out of vent. Then one day filling and "Bang Bang", plus bulge in floor of RV and still no water out of overflow. Quickly realized tank was overfilled. Bottom line, vent tube had become blocked and support straps had given way. Fortunately frame supports saved tank from dropping and only had to replace straps. Floor returned to normal also. Now I closely monitor and time my water flow into my tank.
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Old 10-16-2020, 07:32 PM   #10
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I don't think drilling a hole in the vent line is a good move. Like said, if you are filling your tank via the convenience center selector valve and forget ... you'll have a lot of wet insulation around your fresh water tank as the water will try to exit the vent line once the FW tank is full. Just drop the belly panel that is under your FW tank and make sure the vent line loops about 2" above the tank itself before dropping down thru the belly pan. That will be enough to break siphon ... that's what was the issue with my tank. I'd fill it up and sometimes it would siphon out about 1/4 of what it held or down to the spin welded ftg on the side of the tank that the vent line attaches to.
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