What in Tar nation ??

Ray Arnold

Let's do this thing !
Sep 13, 2008
I was thinking of adding a 2nd water tank to the popup , and I thought I would run this by you to see if this will work , my limited knowledge of hydraulics , the only thing I really know is that water will seek its own level , beyond that I clueless.
The plan is to install a second tank behind the existing tank, on the Fleetwood there is an open area just behind where the original tank is where a 35”x 19”x 7 ½” tank will fit.
I think I can get a tank here Plastic Mart > Plastic Mart

<img src="http://inlinethumb48.webshots.com/43695/2768655630104852032S500x500Q85.jpg" border=0>

Ray&Karen Utah,Bo,and Mister.
2008 Fleetwood Avalon
2007 Chevy Tahoe


Franconia, Pa.
I'll be watching this thread closely. I have been considering the same thing. My biggest concern would be adding all of that weight, especially if it's aft of the axle.

<img src=../Images/icons/icon_smile_pu.gif border=0 align=middle alt="PopUp">'96 Rockwood Signature Series 1280 <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle alt="Tow Vehicle">'07 Ford Explorer
<i>Wherever you go, there you are.</i>


Super Active Member
Aug 24, 2008
Hillsboro, Oregon
The design looks very good.
As a Steamfitter with a fair amount of plumbing knowledge I will say the design is exactly what I would do. My compliments to you.
My only input would be to use at least one inch diameter pipe between the two tanks with a reducer on the tee to get down to the 1/2 inch pump line size. The easier it is for the water to flow through the line to the second tank, the faster the fill-up will be. If you even care about that.
The drain line could also be made with one inch pipe to reduce that time as well.

2004 Fleetwood Utah
2006 Ford Ranger 4x4 Ext. Cab

Edited by - Twisty on April 05 2009 23:36:26


Super Active Member
Apr 17, 2005
Granger, IN
40 gallons of water are about 320 pounds of weight. And that arrangement would have to travel completely full or empty to avoid sway issues.

The Avalon is a big beast - twin axle too, but it really doesn't have much more load capacity that it's 14' single axle high wall cousins at Coleman. The Avalon has a maximum load of 890 pounds. If you have an A/C (about 125 pounds) plus 40 gallons of water (330 pounds) plus a full water heater (6 gallons - 48 pounds), your remaining load capacity is now under 390 pounds. You will need to carefully calculate the balance of your load to avoid overloading the camper's frame/axles.

Steve & Deb (boys are grown & gone)
Aspen & Riley (the 4 legged children)
05 Fleetwood Sequoia & lot's of bikes! <img src=../Images/icons/icon_smile_bike.gif border=0 align=middle alt="Bicycle"><img src=../Images/icons/icon_smile_bike.gif border=0 align=middle alt="Bicycle">

Ray Arnold

Let's do this thing !
Sep 13, 2008
This would add an additional 160 pounds (approximant) at 8.35 pounds per gal. I would not travel with the tanks completely full, only when I was close to my final destination and the last available water fill up place would I fill the tanks. The new tank would be closer to the axels, so the tong weight would no increase that much , just a little more load on the axles, with the air conditioner and generator and all the camping gear I will be carrying I will be just about maxed out cargo wise, but I think it will be ok.

Here is some good info for water systems also > Water Water

<img src="http://inlinethumb03.webshots.com/41858/2474306260104852032S500x500Q85.jpg" border=0>

Ray&Karen Utah,Bo,and Mister.
2008 Fleetwood Avalon
2007 Chevy Tahoe


Fargo, ND (Next Trip - ?)
Jan 15, 2008
Fargo, ND
Hi Ray,

This looks like a really cool mod. I like the idea of the dog water valve. I don't have a dog, but it sounds like a nice thing to have for the dog to always have fresh water.

There is some really good information on your link too. Thanks for posting that.

<BLOCKQUOTE id=quote><font size=1 face="Verdana,Arial,Helvetica" id=quote>quote:<hr height=1 noshade id=quote> I would not travel with the tanks completely full <hr height=1 noshade id=quote></BLOCKQUOTE id=quote></font id=quote><font face="Verdana,Arial,Helvetica" size=2 id=quote>

Just to clarify what Luv2ridebikes said, regarding traveling with water on board, you would not want to travel with a partially filled water tank. Either full or empty is best to avoid the water sloshing back and forth causing sway and possible damage to the tank and/or connections. Think about and 80lb swinging weight attached to the bottom of your camper.

I am looking forward to hearing how this works. I have enjoyed following your other very professional mods.

Gregg - '71 <img src=../Images/icons/icon_smile_bbq.gif border=0 align=middle alt="Barbeque"> Mitchell - '95 <img src=../Images/icons/icon_smile_happycamper.gif border=0 align=middle alt="Happy Camper"> Alex - '99 <img src=../Images/icons/icon_smile_happycamper.gif border=0 align=middle alt="Happy Camper">
1998 Chevy Tahoe <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle alt="Tow Vehicle"> 2008 Jayco 1207 <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle alt="PopUp">
A bad day camping is better than a good day at work.


Active Member
Aug 13, 2008
Check with www.usplastics.com. the prices there are pretty good and they have tanks, fittings, tube, pipe and about anything else made from plastic.

Ray Arnold

Let's do this thing !
Sep 13, 2008
Thank you all for all the input, here is a peek of what I have so far.
I made a mistake in my mesuring and had to change the plan on where to install the tank , it is now forward of the factory tank.
Twisty I think your right on useing 1" pipe, it takes almost 3 times as long to fill the tanks.
I will update in a few days with more info.
here is the link > Water tank install
<img src="http://inlinethumb11.webshots.com/45066/2106371740104852032S425x425Q85.jpg" border=0>

Ray&Karen Utah,Bo,and Mister.
2008 Fleetwood Avalon
2007 Chevy Tahoe

Edited by - Ray Arnold on April 26 2009 22:24:13


Old Dominion Iron Chefs Highland Springs, Va
Mar 10, 2008
Highland Springs Va
Adding that tank closer to the front might increase your tongue weight. Make sure you dont go over the max. Otherwise sounds good.

Peter & Amy, 2008 2407 Starcraft <img src=../Images/icons/icon_smile_pu.gif border=0 align=middle alt="PopUp">, 2003 Dodge Ram Quad Cab 4X4 <img src=../Images/icons/icon_smile_suv.gif border=0 align=middle alt="Tow Vehicle">
08 nights <img src=../Images/icons/icon_smile_camping.gif border=0 align=middle alt="Camping"> -14 2009 nights booked -11 09 nights camped -4


Jul 10, 2008
Coon Rapids, MN
Excellent foresight, Ray. I do agree with hvac that you'll need to be mindful of tongue weight with the new location though. Both the trailer frame's max and your TV's max tongue weight could be issues.

This post definitely gets me thinking -- we've only got a 10 gal tank in ours, and it's underneath the dinette eating up valuable storage space, no less. I wonder if my rookie skills could follow this lead enough [:D]


Super Active Member
Mar 5, 2009
This mod is probably already done since the original post was a few weeks ago, but I thought of this so maybe someone else thinking of this may want to consider this.
What about turing the factory tank around and moving it back a little towards the axle and adding the extra tank where the factory tank was? It would keep the weight towards the axle, away from the tongue.