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Does water evaporate from tanks?


justRich

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Does the water evaporate from the black, gray and/or fresh water tanks in a dry climate when not in use?

We're in our Arizona winter home and using the facilities there. The camper has not moved or been used in a month.

My feeling is that I should be adding a little water to the black tank. But how much? And is it necessary?

Anyone with experience on this topic? Recommendations?

 

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~Rich

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Good question Rich. I've wondered the same thing. Looking forward some more responses. We always try to dump before putting the unit away for a few months but there is always a little material in the black tank. While we can dump when we arrive home it is a bit of a chore. I know water will leak and evaporate from the toilet bowl but don't know about the tanks. Dennis

Trailer: Montana 5th wheel, model 3582Rl, model year 2012

 

Truck: Ford 450 PSD Super Duty, 2002 Crew Cab, Long bed, 4:88 rear end, last of the 7.3 engines, Automatic Transmission.

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The tanks are closed so there would be limited evaporation, but since they do have a vent up to the roof and are not air tight there would be some amount of evaporation. Ambient temperatures would also play a part as the higher they are the more evaporation will take place. Most of us find that the biologic activity that becomes rampant with partially full waste tanks that are left for a long period is a bigger problem than is evaporation. High temperatures tend to encourage the anaerobic bacterial growth, and that is the sort that makes the really nasty, sulfuric odors that can become very powerful. If you are thinking of tanks that are devoid of waste, then I'd doubt that evaporation would be the cause of material drying up on the tank bottoms and walls as long as you keep them half full or so, but it could be if left long enough, just as Don has indicated. I would not leave waste in them for long periods but more from concerns about the bacterial issue than from evaporation problems, but if you do so then it could also dry up if left long enough. A few weeks is probably not a major evaporation problem, but months probably could be. At the least, it would make the materials become more concentrated and might cause a sludge problem in the bottom of the tank.

 

Dump and flush your waste tanks well and I'd just leave them empty, or perhaps half or more filled with fresh water.

Good travelin !...............Kirk

Full-time 11+ years...... Now seasonal travelers.
Kirk & Pam's Great RV Adventure

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The tanks are vented to atmosphere, so there will always be a slight amount of evaporation. It should not be enough to worry about unless you let the RV set for a couple of years,

 

Ken

Amateur radio operator, 2023 Cougar 22MLS, 2022 F150 Lariat 4x4 Off Road, Sport trim <br />Travel with 1 miniature schnauzer, 1 standard schnauzer and one African Gray parrot

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The black & gray tanks have an open air vent, so they will dry out/evaporate liquid over time. Even in fairly humid east Texas, a stick house toilet bowl will evaporate dry in 5 months or so. The sides of the tank (think sensors) will dry out fairly quickly. They do this even quicker when driving, one reason why the sensors are notoriously unreliable, and the reason some rv waste system experts recommend you don't dump tanks on departure, but rather on arrival at the next location. We use our rig normally once a month, so manage to keep the liquid level "refreshed".

Paul (KE5LXU), former fulltimer, now sometimer...

'03 Winnebago Ultimate Advantage 40E

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Personally, I would and do keep a gallon or so sloshing around in both tanks. Yes, it could evaporate eventually but with no moving air it is very, very slow. By keeping a bit of water in the tank I raise the relative humidity in the tank which in turn helps slow or prevent concretion of solids.

Berkshire XL 40QL

Camphosting and touring


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We used to have a weekend RV in southern Arizona and found that over a couple months a couple gallons left in the tanks was enough to keep them wet. We didn't want them to dry out because getting them clean was very difficult (black) or nearly impossible (gray) due to the plumbing routing.

 

We also got tired of the toilet and drains drying out which was a frequent problem at 100 degrees and 10% humidity, adding a drain cover or Saran Wrap took care of that issue. Don't forget to stick a piece over the overflow drains too.

First rule of computer consulting:

Sell a customer a Linux computer and you'll eat for a day.

Sell a customer a Windows computer and you'll eat for a lifetime.

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We dumped at the Cave Creek Regional Park a few weeks ago before returning home.

The dump station there is graded in the wrong direction!

So we had to make the approach from the "wrong" side to keep the drain outlet on the low side and drape the dump hose over the curbing.

 

I'm pretty sure that it was a complete dump. But that sort of thing puts a nagging worry in mind that it could have been better.

So to be on the safe side, I'll put a couple extra gallons in it and not worry until the next time.

Thanks for the advice. I think that we're good.

 

 

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~Rich

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We have seen a couple of the off-level dump sites, used a few wood blocks to jack up the low side of the rig so we'd get a good tank dump.

First rule of computer consulting:

Sell a customer a Linux computer and you'll eat for a day.

Sell a customer a Windows computer and you'll eat for a lifetime.

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We have seen a couple of the off-level dump sites, used a few wood blocks to jack up the low side of the rig so we'd get a good tank dump.

That one at Cave Creek Regional Park was too far off level. . .I gave up with the wood blocks and swung the rig around to the opposite direction (easy to do with a TC).

What gets me about that park is that they now charge $20. to anyone who just wants to dump!!!

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~Rich

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