Do Not Overfill Your Fresh Water Tank!

[Rivernerd]

I hope this issue has not previously been addressed on the forum.  I could not find anything on this topic with a search.  So, here goes.

I have always assumed that the fresh water tank in our 2022 Elite II could be filled until water flows out of the overflow tube underneath the fridge, regardless of the fresh water sensor reading. 

This approach is recommended on p. 61 of our 2022 Oliver Owners Manual:  "fill until water starts to run from the freshwater overflow..."  I have regularly done just that with no issues--until a few days ago.  When filling the fresh water tank, the aisle floor bulged upward, the entire trailer shifted to the curb side binding the door, and then, with a loud CRACK, the backsplash on the sink side of the galley countertop separated by about 1/2" from the fiber granite countertop, because the corner of the countertop near the sink was sloping toward the curbside!  After we recovered from the shock, my wife and I immediately ran fresh water (via the pump) into the gray water tank through the galley sink until the trailer shifted back into equilibrium.  Fortunately, this enabled the aisle floor to level out again, the door to unbind, and the countertop to slowly rise up again to meet the backsplash, so the two once again line up.

When we get home, I plan to re-caulk the joints that separated, and carefully inspect for any additional damage.  So far, all appears to be "back to normal" while we continue our extended trip.

Lesson learned: despite what is recommended in your Owners Manual, monitor the fresh water tank level when filling, and once the sensor reads close to 100%, SHUT OFF THE WATER!  DON'T WAIT FOR WATER TO FLOW FROM THE OVERFLOW TUBE!

[Dean and Mary]

Wow, I’m really sorry this happened. I’ve heard of similar issues with other trailer brands when there’s little or no effective overflow outlet. That’s why most trailers are filled using a flex‑hose insert—to let air escape properly. With the direct connection on our trailers, it’s difficult to manually fill at the inlet and allow that air to escape. In your case, it sounds like the overflow tube may have been restricted, or the incoming water volume and pressure simply exceeded what the overflow tube could handle.

Thanks for sharing this experience. And again, I’m sorry you had to deal with it.

[Townesw]

@Rivernerd
Remove the drawers on the left side of the drawer stack under the kitchen sink. Look for a hatch plate in the bottom of the cavity. If you have one you should be able to remove the overflow tube to check for and remove any obstructions. 
 

 

 

 

The service dept cut that hole and installed the hatch in May 2018 when I suspected that the hose clamp on the through-hull fitting was loose. I have on my to-do list (still) to enlarge that opening to allow easier access to that area between the hulls. I think the factory started placing that access hatch in trailers built after that.

 

Bill 

2018 Hull 313

Edited Friday at 10:45 AM by Townesw

[Rivernerd]

Townesw:

Thanks for the tip.  I neglected to mention that water was actually flowing from the overflow tube when the trailer shifted, yet the bowing/damage still happened.

Our 2022 hull #1291 has a 1/4" plywood cover over a hole in the location you described.  I plan to remove it and verify if there is an obstruction of the overflow tube.

That said, I still plan to monitor the fresh tank sensor when filling, regardless of what I find!

[Steph and Dud B]

Wow. Sorry you went through that! Hope everything's ok. Unfortunately for us, going by the tank monitor is ineffective. It reads full long before the tank is actually full. We will use a pressure regulator when filling and monitor closely, though. Thanks for the warning.

[Rivernerd]

Steph and Dud B:

Good point re: using a pressure regulator when filling the fresh tank.  I have both a filter and a pressure regulator set to 35 PSI on the "trailer" end of my fresh water hose.  Both were in place when the event described above occurred.  

[DanielBoondock]

3 hours ago, Townesw said:

Remove the drawers on the left side of the drawer stack under the kitchen sink. Look for a hatch plate in the bottom of the cavity. If you have one you should be able to remove the overflow tube to check for and remove any obstructions ... I think the factory started placing that access hatch in trailers built after that. (2018 Hull 313)

By MY2026 its now accessible from a hinged hatch under the outside table that replaced the older propane fridge vent and there's no port under the drawer. You've got access to the back of the fridge, the overflow tube and further back you'll even find a 120V for the induction that theoretically could be used for something. 

Problem with the monitors is they get inaccurate unless you're perfectly level, and generally aren't super accurate anyhow. There's a new system in the 27's apparently, don't know if its actually much better. 

[Steph and Dud B]

5 hours ago, Rivernerd said:

Both were in place when the event described above occurred.  

Again, wow! I wonder what went wrong? We've filled that way dozens of times. Of course, 35 psi of non-compressible water can still do a lot of damage if it has nowhere to go, but you said it was venting out the overflow tube. Will be interested to hear if your tube is kinked or blocked somehow. Enjoy the rest of your, hopefully uneventful, trip.

[jd1923]

5 hours ago, Rivernerd said:

I neglected to mention that water was actually flowing from the overflow tube when the trailer shifted, yet the bowing/damage still happened.

Very strange! The fresh tank expanded enough to bow the floor. It was holding pressure, for some period of time, long enough to after the fact use the kitchen faucet to release pressure. Water coming out of the overflow seems contrary to this occurrence. Overflow (must have) occurred only after enough pressure was built up to balloon the tank.

9 minutes ago, Steph and Dud B said:

Of course, 35 psi of non-compressible water can still do a lot of damage if it has nowhere to go, but you said it was venting out the overflow tube.

35 PSI was enough to balloon the tank but not burst the tank or tank plumbing. If the connection was 60 PSI, like our home plumbing, the tank would have expanded more and at some pressure point the tank would burst or blow off a connected fitting.

Of course, this is not normal. Good news is since pressure held, the tank and plumbing should still be good, but keep your eye out for leaking. 

When our tank overflows, it pours out heavy, measured in GPM like the open hose! I'm always rushing to the shut-off asap, so not to waste much water. The overflow is the only way to know for sure you have a full (small) tank of precious fresh water. You could use a gallon counter at the hose. I've never trusted tank monitors, haven't used our SeeLevel display in at least 2 years.

Thank you for bringing this to our attention, but personally I cannot see changing our simple fresh tank filling procedure. IMHO, your tank overflow needs repair or replacement vs. change of process for our community. Anything but waiting for tank overflow would be a once or twice weekly PITA.

I would try a flexible scope up the overflow tube. Remove any screen in the path (replace with new) and debris. Is there some kind of nest up there? Our old hull has no access panels under the kitchen drawers (as Bill pictured above). Your newer hull likely does. It would be great if you can reach in and disconnect the hose clamp to the overflow! (Someday I'll likely cut a trench under both stacks of drawers to have such access and replace that awful ducting as far up as possible.)

I hope you find the reason soon so that you can get back to life as usual! 😎 We'll be reading!

[HDRider]

The tank gauge is notoriously inaccurate.

 

Did Oliver Service say if this has ever happened before?

 

I bet you have some kind of defect in that tank.

 

[Steve and MA]

Reading through this thread, something that hasn't been mentioned as a possible cause is the flow rate of the water filling the tank.  Though a water pressure regulator will inherently slow the water flow due to its restrictive internal passages, it's meant to restrict pressure (PSI) not rate (GPM).  If water can enter the tank faster than the overflow tube can purge the excess, then the flexible plastic tank would have to expand until it had enough back pressure for the regulator to stop the flow.  The point being that a regulator may be of little benefit when filling the fresh tank.

Edited yesterday at 01:43 PM by Steve and MA

[Steph and Dud B]

1 hour ago, Steve and MA said:

If water can enter the tank faster than the overflow tube can purge the excess, then the flexible plastic tank would have to expand until it had enough back pressure for the regulator to stop the flow. 

That begs a question. What's the internal diameter of the overflow tube? If it's equal to, or larger than, the shoreline hose and the plumbing leading to the tank, wouldn't they have the same flow rate?

[Ollie-Haus]

Edit: @Steve and MA was quicker on the keyboard than me but I will leave additional thoughts below. 

I've always monitored the fresh overflow and fill rate closely when filling and flushing the fresh tank. I make sure my fill rate is very slow as the overflow is nowhere near large enough to accommodate a high fill rate. As soon as water starts sputtering out the overflow I shut the supply off. If I want to flush the system for and extended period, I reduce the flow to a fast trickle and monitor while working around the trailer.

The holding tanks are not pressure rated, and even at a relatively low supply pressure such as 25psi, a fill rate say 10% faster than the overflow rate would slowly "inflate" the holding tank. It all depends on the overflow capacity to keep up the the fill rate. A strong stream at the overflow in my mind indicates a pressurized system and needs to be shut down immediately.

Related to jd's comment above, I just happened to purchase a smart phone borescope earlier this morning on Amazon for other reasons, but realize it will be perfect for inspecting various concealed and hard to reach spaces on the Oliver. This may be just the tool for @Rivernerd to purchase for his evaluation, and keep onboard for future inspection needs. 

https://a.co/d/00rWQwkn

Edited yesterday at 04:33 PM by Ollie-Haus

[jd1923]

2 hours ago, Ollie-Haus said:

the overflow is nowhere near large enough to accommodate a high fill rate. As soon as water starts sputtering out the overflow I shut the supply off.

Is this true Chris? When I rush to turn the water off, it appears to have the same volume of the hose filling it. Of course I'm not measuring GPM, but...

OTT uses 1/2" PEX coming in with a restrictor to boot. The overflow is not PEX but a flex tube. Except for Bill's pic above, I have not see the top of the fresh water tank nor the overflow tube since we do not have inspection plates under the drawers.

I just put a screen in the end of our overflow outlet, based on input from a recent post. Before adding the screen, I could fit my index finger inside the overflow to the full length of my finger. No way my finger fits inside 1/2" PEX (mechanics arthritis on every knuckle)! The overflow is likely a 3/4" ID tube.

Back to @Rivernerd's issue =>
The tank held pressure long enough to use the kitchen faucet to release the pressure and relax the flooring. The overflow must have a significant flow restriction causing enough pressure to balloon the tank, somehow also allowing some water escaping.

[Snackchaser]

High pressure could cause enough turbulence to splash water up to the overflow tube creating gurgling and an air lock.  An air lock can effectively block the vent tube.  It's not uncommon, even with large industrial tanks!

It's also possible that floating debris blocked the overflow tube as the tank filled, then it floated away afterwards.  This is intermittent and it's happened with hole-saw plugs that were left in the tank during fabrication.  

I've always instinctively filled the freshwater tank very slowly, just a crack of the valve.  The overflow tube is no match for my hose pressure and volume, and the tank is not designed to be pressurized.  

[Ollie-Haus]

2 hours ago, jd1923 said:

Is this true Chris? When I rush to turn the water off, it appears to have the same volume of the hose filling it. Of course I'm not measuring GPM, but...

OTT uses 1/2" PEX coming in with a restrictor to boot. The overflow is not PEX but a flex tube. Except for Bill's pic above, I have not see the top of the fresh water tank nor the overflow tube since we do not have inspection plates under the drawers.

I just put a screen in the end of our overflow outlet, based on input from a recent post. Before adding the screen, I could fit my index finger inside the overflow to the full length of my finger. No way my finger fits inside 1/2" PEX (mechanics arthritis on every knuckle)! The overflow is likely a 3/4" ID tube.

Well I just crawled under there to get a better understanding of the drain port. Ours is in the form of a plastic flanged bulkhead fitting that appears to extend about four inches up through the bottom hull just off the aft corner of the fridge compartment. It’s ID is about 3/4 inch and upon shining a light up inside, there is a fine mesh screen at the upper end and it appears to have a black fiberish filter material on top of the screen. 

There’s board dividing the fridge compartment from the galley drawer space, so no access to the drain from the outside fridge access panel. 
 

My guess is the mesh and what appears to be a filter material are there to prevent anything from getting into the freshwater tank through the drain. But this also would restrict the flow of water during the filling process. Sounds like there’s a few questions for Oliver service to better understand the principle of design and of course what to do if this filter/mesh becomes clogged over time. 

[jd1923]

1 hour ago, Ollie-Haus said:

My guess is the mesh and what appears to be a filter material are there to prevent anything from getting into the freshwater tank through the drain. But this also would restrict the flow of water during the filling process.

Agreed, a screen insert makes sense to keep insects out. Filter material, why? It does look like a filter, but there's no need to filter waste water! The finer the screen or filter material, the quicker it will muck up, and eventually be closed shut.

Thanks for the picture! I suggested the scope and now I need to get one! The screen/mesh looks somewhat clogged up. Who knows what has collected above it in your 5 years, our 11 years? Hull #1291 has at most 4 years of use!

Could be one of those hole-saw plugs from the tank installation stuck along the path. It irks me how lazy "professional installers" can be. With the right tool it would take a few seconds to retrieve the plugs and a blast of compressed air to quickly clean out the new tank.

Fill the tank more slowly? Filling up at Maverick on our last trip, It took over 10 minutes to fill the tank (28 gal on the counter) and the hose had a very good flow rate. Because it's so slow, I now start filling the fresh tank and dump tanks while it's taking its time filling. For me the 1/2" PEX plus the OEM restrictor makes the incoming water flow slow enough. I'll be checking and likely removing this "filter" instead. On my long list is also removing the Fresh and City Water line restrictors (they restrict flow vs. pressure). Everybody in every RV forever has run the hose until the tank overflows. Camping is supposed to be fun! 🤣

Is the "plastic flanged bulkhead fitting" removable, so serviceable? The screen is relatively close to the bottom, so there's hope.

Given @Rivernerd's experience, I would certainly try to remove that fitting and see if the screen/filter is serviceable. If not, I would take long auger drill bit and turn it by hand slowly into the screen, trying to grab as much of it as possible for removal. Try to remove as much as possible with the bit, wider bits and other tools. Then use the scope again to see if it's clear all the way up and down into the tank. Finally, take a piece of stainless steel screening material, shape it into a cone and insert it at the very bottom. This screen insert could be removed later easily with a needle-nose pliers.

It will be interesting to find out the end result here. I imagine a lot of us will be looking up that overflow tube soon enough!

[Hokieman]

Here’s another photo that shows how it is installed.  Replacing that screen is now on my task list.  Thanks to @Wayfinder for bringing the screen situation to our attention, I would probably have never noticed it.   And thanks to @Rivernerd for alerting us to a potential problem. 

 https://olivertraveltrailers.com/forums/topic/11495-fresh-water-tank-overflow-condition/#comment-126984

Edited 17 hours ago by Hokieman
Added link and comments

[jd1923]

12 minutes ago, Hokieman said:

Here’s another photo that shows how it is installed.  Replacing that screen is now on my task list.

Me too, and thanks for the photo Mike! You can almost read the print on the overflow tube!

Hard to be sure with photography, things closer looking larger and all, BUT the overflow tube sure looks considerably larger than the rest of the plumbing.

 

[Snackchaser]

That's a Through-hull marine fitting.  Oliver probably added the insect screen.

I looked at mine with a mirror and it doesn't have that black stuff.  Me thinks it's clogged!  I'd try poking a piano wire through the mesh while slowly adding water to the tank to see if it flushes out.  Catch it in a white container to see what it is. 

[Snackchaser]

From the looks of those long tanks, and knowing that the level sensors are on the ends, just a few degrees off lengthwise level could result in significant tank level inaccuracies!  Good picture! @Hokieman

 

[mossemi]

I have been following along without anything to add, but I now have a few thoughts.

The fresh water overflow discharge port is, in the words of Google:

So it looks like a 2 piece fitting that requires access to the inside and outside of the hull to install, service or remove.  

So the next step requires a modification to the floor below the bottom drawer below the sink.

This picture of the area below the sink without the drawers in place.  The blue square surrounds a cutout in the rear wall that OTT provided for access to the refrigerator 120V outlet.  The red square surrounds a cutout in the floor that I made with a router, using the walls as a guide.  This access was needed for a prior plumbing modification.  It may also provide access to the freshwater overflow port that would be needed for the installation, removal or repair.  Both of the access ports are normally covered with a thin piece of plywood.

My MOP for sanitizing the freshwater tank in hull 193, begins by mixing several ounce of chorine or a quart of hydrogen peroxide in a 5 gallon water jug and using the boondocking port to pump it into the freshwater tank.  I then fill the tank using a hose at the freshwater fill bib.  I am generally in the area of the Ollie while doing the sanitation job, but I do not monitor the amount of water going in, I just wait for it to overflow.  And I do use a pressure regulator set to 40 lbs. whenever connecting a hose to the freshwater tank or city water bibs.

Mossey

 

 

[Rivernerd]

Thanks to all who have provided valuable insights and photos.  As we have had a busy travel schedule on the road, I have not yet had the opportunity to pull the drawers under the sink or to inspect the underside of the fresh water tank overflow tube in Hull #1291.  For now, we are carefully filling the fresh water tank when we need to boondock, until our pre-planned schedule allows me time to try to "get to the bottom" of what caused our problem.

We will be on the road until the end of October.  I hope to be able to investigate once we get back home.  I will then report my findings, if any.