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Old 07-22-2016, 08:29 PM   #1
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1969 18' Caravel
Dallas , Texas
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fresh water tank below the subfloor

I'm very new to this RV thing and i'm trying to remodel a 69 Caravel.
I've got my new subfloor in and I've flipped the frame and working on the underneath side now.
I'D LIKE TO INSTALL A FRESH WATER TANK UNDERNEATH THE SUBFLOOR IN THE AREA WHERE I'VE SEEN SOME SPARE TIRES BE PLACED.
Couple questions come to mind that I want to make sure i'm not making a huge mistake.

1) The tank that will fit in this area has a bigger depth than the 5" space btw subfloor and bellypan so my tank will be exposed 5 1/2" below the frame. I plan on having some kind of galvanized cover fabricated for it to protect it. DO YOU THINK THAT PERTRUDING BOX BELOW THE BELLY PAN WILL BE SUBJECT TO TOO MUCH POSSIBLE DAMAGE FROM TOWING IN LOW CLEARANCE SITUATIONS?

2) If it is possible to locate the tank there below the belly pan can I have the water pump be above the subfloor? Or does there need to be some kind of gravity factor involved with getting the fresh water into the pump and out to the lines within the trailer?

3) What are the penetrations that will be needed within the tank? One for an inlet from my original fresh water fill cap, Two for an outlet to the water pump, and Three for a drain valve to use at the end of trips/season to completely flush the tank?

THANKS IN ADVANCE FOR ANY ADVICE ANYONE CAN GIVE ME ON THIS!
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Old 07-22-2016, 10:16 PM   #2
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How does Airstream do it? And Why?

I guess you could work around these issues.

#1 The fresh water tank would be exposed to the cold. But not many people camp in freezing weather

#2 It might be a little harder to prime the pump.

#3 Airstream uses a belly pan for aerodynamics. You would be diminishing that feature slightly.

#4 You would be loosing ground clearance. Some people have troubles with gas stations and driveways as it is.

#5 Your tank when full could weigh up to 235 pounds. It would be hanging from brackets. I'd think there could be a problem down the line.

#6 The tank would be a sitting duck. The shield for it would need to be heavy, and the shield would lower your clearance again'

I'm guessing your thoughts on the upside is that you would have more inside storage. Airstreams usually have enough space for daily needs. You could store a lot of things in the tow vehicle

I guess you would be lowering the trailers center of gravity a bit.

But Again……..How does Airstream do it? Although my fresh tank is above the floor , maybe some trailers mount the tanks below. If I'm wrong someone will let us know.
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Old 07-23-2016, 07:54 AM   #3
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70s Airstreams had the tank below the subfloor, so there is no functional problem with you doing this. The pump goes inside the coach, no problem. You will need a fill, a vent, and a suction line for the water pump.

Have you looked at the tanks available at Vintage Trailer Supply? They make a gray water tank that will exactly fit within the rectangular frame members of your caravel. All the fittings are custom so you could get the fittings you need for a fresh tank. You'll still need to support it from below, and relocate the fill to the side, but it would eliminate the clearance issue, move the weight further away from the tongue, and may have more capacity than a tank that would fit in the spare tire area.
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Old 07-23-2016, 07:58 AM   #4
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Originally Posted by mandolindave View Post
. . .
Although my fresh tank is above the floor , maybe some trailers mount the tanks below. If I'm wrong someone will let us know.
What trailer model or MH do you have with the actual fresh water tank above the floor? The fresh water fill on the exterior is certainly higher, but most AS tanks are below the floor IMO. The exterior drain usually runs horizontally from the bottom of the tank, and it usually is below the trailer's framing.

Thanks,

Peter
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Old 07-23-2016, 08:08 AM   #5
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I have a 1973 Argosy 20 footer.

Perhaps I was unclear. My fresh water tank sits on the floor. Sorry, I didn't realize that, that was uncommon. My bad. Thanks for the correction.

Also, my black tank sits on the floor as well. I did know that Airstream tried some experiments with Argosy trailers.

My fresh tank drain is on the side, at the bottom of the tank and runs vertically straight down

Um…." Actual " fresh water tank ???? What other kind is there???
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Old 07-23-2016, 08:17 AM   #6
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I considered this but decided against it because of similar concerns that mandolindave stated.
We have the same size with an 18' Traveler. Water is 8.3 pounds per gallon and I just didn't want to add that weight....don't forget if you increase the freshwater tank then what about the black/gray tank(s). Mine has 10 gallons of freshwater and 12 gallons of black so I could potentially be carrying a little over 185 pounds of water alone...almost 10% of the trailer's weight
I just got a 5 gallon jerrycan and will refill the trailer as needed.
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Old 07-23-2016, 08:19 AM   #7
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Otra15

Do most Airstreams, or any, have a fresh tank that hangs 5 1/2 inches below the belly pan.

That was the issue with the design modification that I had concern about.
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Old 07-23-2016, 09:03 AM   #8
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I am guessing that you might not have a shower in your trailer. I have a 28 gallon fresh water tank, along with 10 gallons in my water heater. That's about four showers for me or my youngest, one shower for my eldest ha ha, I carry four six gallon jerry cans, in my tow vehicle.

I have mentioned this on other threads. My camping club made a portable water heater out of a RV water heater that works with with one of those shower tents. You wouldn't need it for a camp ground but it would work for boon docking and you wouldn't have to cut up your trailer.
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Old 07-23-2016, 09:08 AM   #9
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Steve

In response to the fresh water tank/waste tank volume ratio. If at a campground, you can let the waste water drain as you use it.

I also have the big blue external waste tank. I don't have a gray tank on mine.
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Old 07-23-2016, 09:11 AM   #10
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My Excella has the water tank in a galvanized box extending about 5 inches below the belly pan. It's located between the axles so full or empty it has no impact on the balance of weight.

My fresh water capacity greatly exceeds the grey capacity, so when boondocking we have to manage our showers from the perspective of the waste tank, not the amount of freshwater on board. In fact I only fill the water tank about 2/3 full because anymore is just dead weight.
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Old 07-23-2016, 12:26 PM   #11
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freshwater tank

In my 70 globetrotter, it had it's watertank slightly in front of the axle. Below the floor and about 3 inches below belly pan.
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Old 07-23-2016, 12:42 PM   #12
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Quote:
Originally Posted by OTRA15 View Post
What trailer model or MH do you have with the actual fresh water tank above the floor? The fresh water fill on the exterior is certainly higher, but most AS tanks are below the floor IMO.
Lots of 60s and older Airstreams had a galvanized fresh tank in front under the gaucho, above the floor.
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Old 07-23-2016, 02:27 PM   #13
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I get why you monitor your grey tank.

Quote:
Originally Posted by LY007 View Post
My Excella has the water tank in a galvanized box extending about 5 inches below the belly pan. It's located between the axles so full or empty it has no impact on the balance of weight.

My fresh water capacity greatly exceeds the grey capacity, so when boondocking we have to manage our showers from the perspective of the waste tank, not the amount of freshwater on board. In fact I only fill the water tank about 2/3 full because anymore is just dead weight.
I imagine that Airstreams original thought was that a portion of the fresh water was going to end up in the black tank.( Any of the water that was consumed, any water that was used for flushing.)

Way back when, Wally had instructions in owners manuals, instructing folks to dig a gopher hole to empty grey tanks as you used the water. Of course drinking trailer water, and dropping grey water is a bit of a thing of the past.
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Old 07-23-2016, 02:49 PM   #14
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Have been drinking "trailer" water from back in the fiftys until now.
Do not recall ever having died or becoming ill from the practice.
Approximately 98 percent of our bath and dishwater
Are returned to good old mother earth from which it came without wasting resources to "treat" it. Or having to haul it somewhere to do so.
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Old 07-23-2016, 03:00 PM   #15
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I mostly drink jugs of water from home.

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Originally Posted by dannydimitt View Post
Have been drinking "trailer" water from back in the fiftys until now.
Do not recall ever having died or becoming ill from the practice.
Approximately 98 percent of our bath and dishwater
Are returned to good old mother earth from which it came without wasting resources to "treat" it. Or having to haul it somewhere to do so.
Yeah lots of people drink trailer water. I use it for cooking, and coffee.

It's just that there are lots of ways for water to get contaminated, and then sit in a tank for days on end. A few fairgrounds that I go to have signs saying NOT to drink the water.

I saw a guy rubbing the end of the water supply hose on his head while he showered himself. I've seen people wash their hands then drop the hose on the ground where horses have been. And who knows what mold or mildew is in your tank a month into the camping season.
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Old 07-24-2016, 08:33 AM   #16
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Quote:
Originally Posted by mandolindave View Post
In response to the fresh water tank/waste tank volume ratio. If at a campground, you can let the waste water drain as you use it.
I also have the big blue external waste tank. I don't have a gray tank on mine.
Not in California! We want to do allot of dry-camping at the state parks so I have made provisions. I only have a Kitchen Sink and Toilet so I routed the sink to a gray water dump and can collect that in a jug. Next i have installed Valterra blade valves so that I can rout the sink into the black water tank with a separate dump.

We lived on a boat for almost 20 years and have a Motorhome that we spend the winters in...we did/do NOT drink from the tanks. Much healthier to either bring water from home (snow driven) or just pick up bottled water for our & the dog's drinking water.
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Old 07-25-2016, 07:40 AM   #17
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I would move the tank close to the axle. You will have less variation in tongue weight when the tank is full vs empty. It would also help for ground clearance issues.
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Old 07-28-2016, 09:12 PM   #18
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Thanks to all that responded

I now have a better idea of what has been done in the past and present and maybe how I should modify my plans.
I think i'll definitely move the tank back more towards the axel.
It will give me the full rectangle area within the frame members to put a tank in (which like mentioned,VTS has ones that are the exact same size length width and depth to fit in that area so that will eliminate all the possible problems of having the tank up in the spare tire irregular sized area.
THANKS AGAIN TO ALL THAT RESPONDED.
it's really nice to have this sounding board to bounce ideas off of and get the feedback that really can make a difference for years to come.
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Old 07-28-2016, 09:50 PM   #19
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Bayrat hit my concern. Empty to full weight variation and that far forward will have a significant impact on tongue weight. If you move it closer to the axles you'll have better weight distribution.
Sticking down is ok, mine sticks down about 5" Ina galvanized pan, but that's between axles which means it's pretty much impossible to bottom out on.
As far as figuring ground clearance goes, Draw a line from where the wheel touches the ground to the bottom of your jack when retracted. It it's above that line it's pretty safe from grounding.
Modern rv water pumps are self priming so they will pump the air in the line to pull up the water to the suction of the pump, do being under the pump is no problem!
Consider a smaller tank for the small trailer. You can get a shallower tank from VTS and have them install connections you specify to get a custom fresh water tank. Don't feel your only option is the big FW tank they stock.
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