Getting all the water out of the water tank

WilliamA

As most of us have already found out, it's impossible to get all of the water out of the water tank on our T@Gs simply by running the pump. Now, this isn't a big deal at the beginning of the storage season. To get it out after sanitizing, just put a block of wood down under the tongue jack and crank the trailer up so it's angled to the rear. At the campsite, that's not so easy. I'm sure they left out the paragraph in the instructions that says:
"To get the last third of the water out of your water tank, simply pull your trailer under a stout tree, hook a chain hoist to the trailer tongue and stand the trailer up on end. Run the pump until it's empty."

Perhaps that's a bit hyperbolic (cruel, even) but if nothing else, it relieves tension through comedy.
I've elected to take on the task of modifying my water system so that I actually can use the bottom third of the water in the tank without acrobatics.

The problem, put in scientific terms:
The problem is simply that the tank outlet is an inch above the bottom of the tank. The opening diameter at the threads is 9/16". To determine how much water won't pump, add those two numbers. My math gives an 1 9/16 inches. The reason you must add 9/16" is because when the water level reaches the TOP of the outlet opening, the pump will begin to cavitate, or suck air. It will eventually draw the tank down to the bottom of the outlet at 1 inch but that will include a lot of sputtering and spewing of water out the spigot on the sink because the water line has air in it along with the remaining water.
The tank is 3 1/2 inches deep from top to bottom. The volume of the tank is 11 gallons, give or take. Now divide 11 gallons of water by 3.5 inches and you get 3.14 (Pi?) gallons per inch of water in the tank. So if the outlet is 1 inch up the side of the tank at the bottom of the opening, that leaves 3.14 gallons of water that can't be pumped without raising the trailer tongue. I'll be the first one to say that raising the trailer tongue is pretty easily done. Even so, unless you raise the trailer tongue by many inches, there will still be a significant amount of water that can't be pumped. My unofficial estimate is that there's easily a couple of gallons of un-usable water in the tank. With only 11 gallons to work with, that's a significant amount of the total.

So I'm off chasing some sort of solution to the problem. I've (almost) found one. Here's what I've done so far.

Here's the culprit. You can easily see the outlet for the tank is an inch above the bottom of the tank. Add to that the tank opening and you get a lot of frustration and wasted time trying to coax it out in a useful way. The placement of the tank bung shows a comical lack of attention to detail. Comical, that is, unless you are the one trying to get the useable water from the tank.

I started by removing the outlet line and associated bits from the plumbing. This is easy and takes a couple of minutes with a pliers, small flat tip and needlenose. The only difficult part is turning the threaded pipe plug out of the tank. First, (assuming the tank is empty, or nearly so) I removed the black twist-off connecter at the pump inlet.
I just traced the hose up from the tank to the filter housing on the end of the pump. Second, I carefully removed the clamp that holds the hose to the outlet hose barb on the tank. That'll be the clamp right next to the tank. A bit of work with a small flat tip screwdriver and needlenose pliers will get the clamp off. Once both plumbing bits were disconnected, I pulled and twisted the whole assembly up to get the drain loose from the caulk where it goes through the floor. Not hard to do. If you look closely at the threaded bung where it screws into the tank, you'll see which clamp I removed.

I ran off to town and grabbed a foot of 3/8" water hose and a small tube of plumbing putty. It's the kind spec'd for plastic and potable water.

The outside diameter of the hose is a smidge more than 9/16". That's exactly right for a tight press-fit into the inside of the outlet bung. The hose has a natural curve to it so I cut off a few inches and stuffed it inside the outlet bung. I cut the other end off level with what will be the bottom of the tank.

Here's what it looks like now with the new tank pickup in place. Keep in mind that the tank pickup now turns with the threaded bung.

The new hose pickup will spin with the bung as I screw it back into the tank so I marked the top of the bung to keep track of where the pickup is pointed. In this case, when the mark is pointing up, the pickup will be at the bottom of the tank.

The fly in the oatmeal of the project is that I still need to file out the tank outlet so the pickup will easily slide inside. There's a lip on the inside of the threads in the tank. The fitting is a pipe thread so it's tapered as it screws in. Not sure why the inside of the fitting in the tank has that seat other than to add stiffness to the tank opening. To enlarge the inside opening, I'll need a short round file. My round file is too long to make the corner between the cabinet and tank opening so that step will have to wait until my next trip to town. I can console myself with the fact that no plumbing job in my life has EVER been done without at least two (or more) trips for parts/tools. I'm nothing if not consistent.

Here's the pipe thread sealer I use on plastic bits. It's potable water safe and approved for plastic of all sorts. Works well and never gets hard.

I'll keep you informed, but assume that other than putzing with the opening until the new pickup slides in, the project is going to work fine. If I really wanted to be neurotic, I'd have glued the hose into the bung. I'd be very surprised if it ever falls out though.

WilliamA

LuckyJ

You solution is about what I have in my head for mine, expect that I think I want to try with a flexible hose (thinking medical rubber and a small weight at the end.

But you solution good be the KISS way to go. Nice work. And if you mannage to turn it in the right position, I do not see why it would not work. One question. i know that with tye natural shape of the hose, it will go to the bottom or close. But if it reach the bottom, do you think it could work as a succion cup and stuck flat to the bottom of the thank, preventing it from succing water? This is just a tought that you probably tough about already.

Oh yeah, I found out that the best solution to get all the water out or almost is to back the right wheel on a 6" block and them lift the tongue as high as possible with a front loader tractor. You should get all but a few ounce. Very nice at a campground! Lol

WilliamA

Yeah, I've thought of that. I marked the "clock" of the hose so I can turn it enough to give a little angle off flat at the inlet. I considered using flexible hose with a "clunk" (weight) at the end but any hose flexible enough to follow the clunk could collapse under vacuum. This hose is pretty rigid and will no doubt stay where I point it. We'll see.

If you took a tractor to the campground, you could also use it to charge batteries!

WilliamA

2jgcampers

I'm just curious-would a factory solution have the outlet on the bottom of the tank and the tank sitting on maybe 1 1/2" feet, 1 on each corner. Would that allow enough space for a drain or would that reduce usable space too much? Is the tank material strong enough to handle the pressure without bowing in the middle away from the corner supporting feet? Alternatively, I wonder why the tank can't drain directly out of a drain in the bottom of the tank through the floor? Would the jostling of the rear of the trailer be a potential problem?

TomD

Curious why the need to totally empty the water tank. Is it freezing temps? If not then what?

WilliamA

Twograms,
It would be an easy thing to simply design the tank with the outlet in the bottom. The plumbing could simply drop down below the floor and come back up under the sink. I actually like the size and shape of the existing tank were it not for the drain location.
Tom,
Consider that your trailer is your car instead. It's got a 20 gallon gas tank but the fuel inlet is a third of the way up the tank. You could go a third further if you could use all of the fuel but instead would have to stop many miles before the tank is empty. I use about 3 gallons of water per day when camping. If I could use all the water in the tank, I could reliably go another full day between fills. Additionally, I usually make my long highway drones with an empty water tank to save weight and fuel. I carry a gallon jug of water and fill the main water tank upon arrival. Carrying unnecessary weight is anathema to me. I agonize over the weight of socks but wouldn't think twice about a hundred extra pounds of water? Doesn't make sense to me. That's a false sense of priorities...

WilliamA

TomD

My better half uses water like we were at home. I’m filling the 5 gallon at least once a day. Oh water boy. Oh water boy. I come running.

WilliamA

My ex's used to use water like it was water. Now they just use my alimony payments like it was water...

WilliamA

TomD

Tabnero

I loved this post. made me laugh as I listen to my exact plumbing life. Thank you for posting and I will help my friend do this.

russ1436

My tip for getting all the water out of the tank is to open the drain prior to heading home. All the up and down hills has always left the tank totally empty.

Doesn't solve the problem of having a couple of gallons on unused water - but at least old water isn't sitting in the tank for prolonged periods

OldFatDog

@WilliamA -- So now that you've had this mod in place for awhile -- is it working as well as you hoped it would? Would you do anything differently?

OldFatDog

@TomD said:
Curious why the need to totally empty the water tank. Is it freezing temps? If not then what?

For one, after winter storage. Whether you use some sort of anti-freeze, or vodka (as one clever T@Gger suggested), you want to be able to flush it out before filling it with fresh water. In my experience, it takes a lot longer and wastes more water to flush that stuff out if you can't completely empty the tank each time.

Similarly, we had some water sitting in the tank that tasted funky for whatever reason. I flushed, added a little bleach, flushed again several times. But we still get a slight bleach taste, because the tank never really emptied completely between flushes. (And if we're still getting bleach taste, we've probably still got some funk in there, too.)

I guess it's like having a little black paint left in the bottom of a can. You can add as much white paint as you want, hoping to get white eventually, but the best you can hope for is grey.

That's my $0.02 worth.

WilliamA

It works well. I just drained and treated my tank yesterday and no problems. I treat my tank a couple of times a year. Just remember when draining to crank the tongue jack high to get the water to the back.
For me, if I get a slight odor of bleach it's not a big deal. I probably overtreat my water system but havent had problems either. My pet peave isn't bleach smell but rather the taste of RV antifreeze. I'm not going to use that again if I can avoid it. Takes a few fill drain cycles to get rid of that.
WilliamA

TomD

OldFatDog....good points. I’m going to use the vodka next year.

Mahojin

I’m like Russ. Open tank on the final leg home, or even mid-road trip. Dry as a bone.

Mccrusn

(Corrected!) Thanks WilliamA! As always... well written and executed! It seems like the only "fix" we have available to us. I like my T@G.... and expect it to be a big part of my life in the next few years as we travel... but it's things like this that make me wonder if anybody at NuCamp has ever actually camped and USED their products? If you only have 11 gallons available to you... why would any engineer design it in such a way that you could only access 60 ~70% of it? Like you... I don't like to carry unnecessary weight...and always be contending with "old water" in my tank.

WilliamA

Mc,
Rhetorical question I assume.
Busload of engineers looking at the smoldering hole in the ground:
"Well,
It SHOULD have worked".
Seriously though, Having disassembled my T@G (several times) just for fun, I like, as the germans would put it: " Die Gestalt". Overall, it's a pretty cohesive piece of work and does what they say in the commercials. If they were listening though, I'd whisper that the bung should be in the bottom. After all, that's where nature usually puts it...

WilliamA

CampHub

@WilliamA Another "Gold Star Winning" modification. Thank you for sharing!

LuckyJ

@WilliamA i love the comment about where ther nature would have put the bung! Lol

Michigan_Mike

Would JB Weld work well for an application like this? Why not eliminate the side water exit port (cap it off) and install a fitting at the bottom of the tank as nature does? No guts, no glory!

Verna

There must be an RV industry reason for the outlet to be on the side. Only the black tank on the T@B’s have an outlet on the bottom, but the gray and fresh water have their outlet on the side, near the bottom, also.

Michigan_Mike

At any rate a little water in the freshwater tank shouldn't hurt a thing. If it freezes during the winter as long as you've dumped the bulk of any water in the tank, the remnants will have enough room for expansion. I've never had any issues after winter storage here in Michigan.

BBsGarage

@Michigan_Mike said:
At any rate a little water in the freshwater tank shouldn't hurt a thing. If it freezes during the winter as long as you've dumped the bulk of any water in the tank, the remnants will have enough room for expansion. I've never had any issues after winter storage here in Michigan.

I guess it depends on how long its in there, could get pretty skanky after a while.

OldFatDog

From a practical sense, I'm less concerned about emptying the tank for storage as I am about having as much water available as I can during a trip.

We were camping a couple of weekends ago on not-so-even ground. It wasn't crazy off-level, but enough. I had the front of the trailer jacked up as high as it would go (without actually lifting the hitch wheel off the ground) and we were still pulling sputters from the sink with more than half of the water tank full.

I have not (yet) done the hose fix that @WilliamA outlined above, so that might make my next suggestion/question moot. However....

What kind of clearance is there above the water tank as it extends under the bed?

I thought about the possibility of lifting the "far end" of the water tank with a wedge -- in order to tilt the tank in the direction of the drain/pump intake.

Thoughts?

OldFatDog

I think I just answered my own question ("No") -- I found this photo from an earlier post by @WilliamA:

LuckyJ

I can confirm this pics, since I did remove the bed floor from my T@G as well, but since we do not have the XL, the tank goes all the way. But did you guys realized that for the XL owners, you have just found some extra storage space!!

As for why the water port is on the side, I can submit a couple or reason.

The tank sits directly on the floor, so that would mean trough the florr plumbing and working from under the trailer and back into the trailer. As is, all is protected.

Second, in order to have a connection to a water tank for pluming, you need some kind of thicker ledge for treads, so probably a 1/4 to a 1/2" of water would still be left in the tank, even if outlet would be from under the tank. Put that to the side, you still have about 1/4 to 1/2 of plastic, plus the full diameter of the water line that start to suck on air as soon as water reach the upper side of the water line.

And also, since the tank is on the floor, it is flat, so that also prevent the water from reaching a lower corner where water would be picked up.

The only best solution for us with a flat tank would be resses treaded hole (lower than the tank floor) and trough the floor water line. It is High density polyethellen, so it can be welded and mod, but modified pluming and some work is involved and it could be harder to remove the tank if needed be, since is as to be pull out from inside the sleeping quarters.

Best ans easiest solution for me is what Will did with an elbow pointing down in the tank and slithly tiliting the trailer to the rear left corner.

Sparrow

I was successful at my last trip before winterizing to just open up the bottom valve. By the time I got home it all bounced out. Then added the vodka till spring.

OldFatDog

@Sparrow said:
...Then added the vodka till spring.

How much vodka? And did you put any into the drain to fill the trap?

Sparrow

Sparrow

What if the hole was placed lower (at the bottom of the tank) and then the pipe inside was trimmed. The original hole would be plugged