Water Tank Siphon Problem

[tom463219]

I installed shut off valves on my water tank overflows to prevent losing all my water siphoning out. I fill the tank and when I see water coming out of the overflows I shut off the water, and quickly close the overflows.



The problem I have is when I open the overflows, even one of them, the water creates a siphon draining almost all the water. I have tried shutting off the pump, opening a water faucet to release the siphon, but it does not work. I have used some water before opening the overflows, but that makes it worse. Water continues to come out, almost draining the tank.


Any one have a solution to this problem?

[PPOSS]

Is it possible that closing off the overflow vent will seal the tank and possibly cause a vacuum issue? Normally the vent is pumped off the top of the tank precluding it from siphoning the water out. I know when mine is full it leaks water out on the highway for a short while.

[JimD]

I had 3 valves on my vent/overflows and closed them after filling. After reaching my site I mostly waited a day before opening one for venting because, as you mentioned, the tank just started to siphon.

I forgot to open the vent valve on one of my trips for 2-3 days but it didn't affect inside water flow. When I finally remembered to open it, there was a noticeable inrush of air so the tank was definitely under negative pressure. The moral of the story - if you install shut off valves, don't forget to open them.

I recently relocated all 3 hoses to a level at least a foot above the tank. It seems to work much better as I can now open a valve without it siphoning at all.

[tom463219]

Originally Posted by JimD

I had 3 valves on my vent/overflows and closed them after filling. After reaching my site I mostly waited a day before opening one for venting because, as you mentioned, the tank just started to siphon.

I forgot to open the vent valve on one of my trips for 2-3 days but it didn't affect inside water flow. When I finally remembered to open it, there was a noticeable inrush of air so the tank was definitely under negative pressure. The moral of the story - if you install shut off valves, don't forget to open them.

I recently relocated all 3 hoses to a level at least a foot above the tank. It seems to work much better as I can now open a valve without it siphoning at all.

I think I will have to do what you did and extend the vents and elevate them above the tank. This trip I kept the vents closed for a day and went underneath the rv and looked at the tank and it was noticeably under negative pressure. I opened the vents to equalize and lost 2/3 s of my water. Where did you relocate the vents to?

[freetime58]

following with interest

[Stavman]

I usually leave my valves installed closed, I'll check to day to see if it's negative pressure or not

But the valves are a must for sure

[JimD]

I extended the hoses using Pex tubing up into the outside shower/water fill cabinet. Just punched a hole in its bottom and ran the tubing with valves up against the wall. Since this cabinet is waterproofed it seemed like a good place to put it.

Previously when I had my valves on the bottom edge of the rig I would be filling the tank in the cabinet while having to constantly stare down the side waiting for water to come out and then rush to shut the valves and turn off the hose. Now it is right there in front of me. When filling I have a shutoff valve attached to the hose end so I can easily start/stop or lower the filling speed.

My previous valves were located low and under where the slide came out which made it inconvenient to get to. This is one reason it was easily overlooked. So much easier to get to now. I think I can drive with one valve open and not worry about any siphoning.

[wiarcher]

I have a 2020 Redhawk 22C and my wife and I are in the middle of an extended road trip which involves regular periods of boondocking. We have been running into problems where we run out of water prematurely. We have even resorted to using bottled water to flush the toilet and generally limiting our water use, but we still run out after only a day or so while both the grey and black tanks continue to register as empty.
I called Jayco customer service and it appears that this must be a common problem because a solution was offered immediately - take a cable tie and gather the three overflow tubes and attach them higher under the vehicle. Seriously this is a major design defect, one of several that I am discovering, and that is their solution.
I have read with interest the solutions forum members have come up with and it appears that this is a problem going back several years - why has Jayco not fixed it?

Any additional, less complicated solutions than installing shut-offs would be appreciated.
Thank you all

[Joey55]

I recently went to the factory at Middlebury, IN and was told that the siphon problem only applied to a few RV's, mine included. Their solution was to loop and cable tie the three overflow lines up high. They said it was natural to maybe lose a few gallons on turns and braking. I can't say how well this will work but if it doesn't I'll try more.

[rgolding]

Many years ago, I joined all 3 vents together and ran the single vent tube over to the water/utility bay on the driver's side. Fill the tank to overflowing (water coming out this vent). Leave this vent closed for a day or the equivalent of 2 showers. At that time, I hook a vinyl hose to the overflow line keeping it above the water level and let the tank vent to get all the extra water in the vent line back in the tank and prevent the syphon draining. Currently , we have lived like this at a private club for the last 6 weeks. I refill every 3 days and with the measurement of grey water drained into a 5 gallon bucket, guesstimate, we are using about 12 to 13 gallons per day, for the 2 of us. Yes, I realize I am not including the water that goes in the black tank. I chose not to measure that. ;-)

[tom463219]

Originally Posted by rgolding

Many years ago, I joined all 3 vents together and ran the single vent tube over to the water/utility bay on the driver's side. Fill the tank to overflowing (water coming out this vent). Leave this vent closed for a day or the equivalent of 2 showers. At that time, I hook a vinyl hose to the overflow line keeping it above the water level and let the tank vent to get all the extra water in the vent line back in the tank and prevent the syphon draining. Currently , we have lived like this at a private club for the last 6 weeks. I refill every 3 days and with the measurement of grey water drained into a 5 gallon bucket, guesstimate, we are using about 12 to 13 gallons per day, for the 2 of us. Yes, I realize I am not including the water that goes in the black tank. I chose not to measure that. ;-)

Took your advice and joined the vents together, and ran the line to the water bay. Problem with water siphoning has been solved. Thanks

[Bullitt6283]

For those putting loops into the overflow drain lines, remember to blow them out or somehow drain them so they don't freeze in the winter.


.

[Marshmellow]

Originally Posted by freetime58

following with interest

me too, I seemed to have lost a bit of water on my last trip, I usually have full hook ups but this time ran out of water, I didn't notice any water syphoning out under the RV though???

[SoulReflection]

Originally Posted by wiarcher

I have a 2020 Redhawk 22C and my wife and I are in the middle of an extended road trip which involves regular periods of boondocking. We have been running into problems where we run out of water prematurely. We have even resorted to using bottled water to flush the toilet and generally limiting our water use, but we still run out after only a day or so while both the grey and black tanks continue to register as empty.
I called Jayco customer service and it appears that this must be a common problem because a solution was offered immediately - take a cable tie and gather the three overflow tubes and attach them higher under the vehicle. Seriously this is a major design defect, one of several that I am discovering, and that is their solution.
I have read with interest the solutions forum members have come up with and it appears that this is a problem going back several years - why has Jayco not fixed it?

Any additional, less complicated solutions than installing shut-offs would be appreciated.
Thank you all

Would this issue also affect a 22J? If so, I am struggling with the "take a cable tie and gather the three overflow tubes and attach them higher under the vehicle". I thought this problem only related to the fresh water overflow.

What are the other two?

Granted, I have not climbed under my 22J but have filled the fresh water tank to overflow and observed water running out under it when full. I have not been boon docking (with this virus) so I haven't experienced the syphoning.

Should I run an extension from the overflow up thru the outside shower?

[Berjr]

At least 1 of the overflow outlets needs to be higher than the tank to break the siphon effect. I capped off 2 of the 3 in our Greyhawk and attached the 3rd (uncapped) to the floor above. I haven't had an issue since .

[Darkzell]

I went a little over board on my solution to the siphoning. I added a gravity fill to the back of the trailer to act as a air vent. Worked great so far with no loss of water and never have to worry about collapsing the tank. There was a pipe from the outdoor kitchen tank that ran to the back so I just extended the hoses and followed it up. Hardest thing was cutting a hole in the trailer and getting that blasted black underbody plastic covering back up.

[Case79]

So why did Jayco use 2 vent lines? I have a 2019 Eagle HT and it has a small white vent line and a large green white vent line with a one way rubber valve. The large tube vents first and it dumps gallons of water after I turn the water supply off.

[Wally22j]

We have a 2018 22J and found ours does have the siphoning problem. We usually camp with water connections but tried a little dry camping. I filled the fresh water tank until water came out of the overflow. The sensors indicated the tank was full. Traveled approx. 15 miles to the campsite and discovered the tank level was a little over 1/3 full. Thought the sensors must be off (like the waste tank sensors). Refilled tank again and watched this time and saw water pouring out from the hoses underneath the unit. Dealership service advisor had no clue how to stop it. I have been following these posts as it seems to be a popular problem.

[RFSTech]

I have a 2019 Greyhawk 29MV and am trying to solve the problem as well. Out of frustration during our last cross-country trip I stopped at a TSC and bought fittings to join all 3 overflow hoses together and then put a cap on the last one. Keeps from losing water while traveling but, as others have mentioned, need to make dang sure the cap in removed before using any water inside or the fresh tank collapses. Still looking for a better idea. I think I'll try the solution others have mentioned by removing the cap underneath and extending that hose to a higher location above the top of the fresh tank. I also like the idea of adding a gravity fill as using the water pump to "pull" five gallons of water at a time into the fresh tank is pretty rough on the pump (and takes about 10 minutes per 5 gallons so gravity fill would be much faster).

[dynarider]

If the tank vent is installed properly it is physically impossible to siphon the water from the tank as the vent will only draw from the top of the tank. dealer and manufacturer are BS'ing you if they say it is installed correctly.