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I'm at the point in my build that I need to get serious about my water tank, inlet and venting. I ordered a 33 gallon from www.classacustoms.com We had originally thought we were going to use 7 gallon portable tanks but decided on a permanent solution but expect we still may keep a spare container for any extended boondocking periods. I'm going to install the tank above the passenger rear tire wheel well and just below the bottom of our bed frame. I was going to orient the fitting towards the front but have decided to have them at the rear and know that regardless of the location, filling and venting will have to be addressed. I've changed my mind on the gravity fill from the inside to now going with an exterior mount but using one that has a keyed entry. I found this one on amazon and it will take a few weeks to arrive. It also has a vent line port. I'll be mounting the fill on the passenger side just below the slider track and at the location of the water tank inlet and my connecting hose maybe only a couple of inches. I've read other threads related to all types of rv's and the issues they've had with the water tank sloshing and loosing fresh water thru their vent line and wanted to kick a few ideas at our group. One idea I had was to install a valve in the vent line and close it while driving but know that I'll forget to close it after I've used my water and will lose some of my water while driving. My 2nd idea would be to run the vent line up the van wall and loop it back down to the vent port on the gravity fill but haven't tested it yet. Would this work? I'm looking for other simple ideas as well.

For the record: I'm not endorsing the items mentioned in my post and have no affiliate links to it.

Autobestown RV Water Inlet Cap Recreational Vehicle Water Filling Inlet Locking Cover Cap with Keys
 

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I have never had it slosh out of the vent on this one. My tank is above the passenger wheel well below the bed and is a 21 gal one.

61539
 

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Hi,
Mine is really simple. My 17 gallon tank extends a couple inches into the sliding door area, and there is a threaded 1 1/4 inch fitting on the top of the tank near the sliding door. I have a threaded PVC plug that fits the threaded tank fitting. To fill I just, open the sliding door, unscrew the plug, put the fill hose into the fitting, and fill the tank -- air venting from the tank during the fill easily flow around the fill hose because fill hose is much smaller than the 1 1/4 fitting.
The only venting on the tank is a 1/16th inch hole drilled in the 1 1/4 inch plug -- this has worked just fine for us, I've never seen any water come out of the little vent hole. Never had any problem with the small vent hole not providing enough vent area even with the pump/faucet on full.

Details here: Our ProMaster Camper Van Conversion — Plumbing and the Fresh and Grey Water Tanks – Build A Green RV

Simple can be good :)

Gary
 

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A word of caution about your 33 gal fresh water tank over your rear tire. Water weights 8.3 pounds per gallon = 274 pounds over that tire, if full. I have the same size tank over my passenger rear tire on my MH (Trend) and only carry about 10 gallons when traveling so as not to over load the tire (LT225/75R/16). Think about balancing weight over both rear tires.
 

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A word of caution about your 33 gal fresh water tank over your rear tire. Water weights 8.3 pounds per gallon = 274 pounds over that tire, if full. I have the same size tank over my passenger rear tire on my MH (Trend) and only carry about 10 gallons when traveling so as not to over load the tire (LT225/75R/16). Think about balancing weight over both rear tires.
True, although when we design DIY & if this is an important issue for the designer/builder “stationary build loading” & “non-stationary loading” such as gas tanks, people, pets, fresh water, grey or black water, & changes in cargo would all need to be considered. Where it is best to do what you suggested and balance the loads, it might impede an otherwise more functional design. I considered such things when designing my DIY & kept “weight & balance” in mind but not as a primary parameter.

I do believe it is more important to consider dynamic roof mounted weight and keep as low a center of gravity as practical, but this did not keep me from utilizing my upper interior space for lighter items storage. I’m hoping this helps me on winding roads & windy conditions.
 

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Discussion Starter #7
A word of caution about your 33 gal fresh water tank over your rear tire. Water weights 8.3 pounds per gallon = 274 pounds over that tire, if full. I have the same size tank over my passenger rear tire on my MH (Trend) and only carry about 10 gallons when traveling so as not to over load the tire (LT225/75R/16). Think about balancing weight over both rear tires.
Thanks for the input on this topic, keep them coming and the pics are helpful. Great point about the weight distribution. I should be fairly balanced as my driver side will have my batteries, more cabinets than the passenger side and our Dometic CFX75DZ cooler. We'll also try to minimize driving with a full tank of water and fill up closer to our spots.
 

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I have never had it slosh out of the vent on this one. My tank is above the passenger wheel well below the bed and is a 21 gal one.

View attachment 61539
I think I have that same fill port, but I havent installed mine yet. What a great idea to put it horizontal like that. Question: What hose did you use from the fill port to your tank and how did you attach the half inch braided tube to the vent port?
 

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concerning weight distribution

FWIW

The positioning of auxiliary equipment and superstructures must ensure even transverse
load distribution. For each wheel, a variation in the nominal load on the wheel (1/2 the
load on the axle) of ±4% with respect to the permitted tyre loading is possible without
jeopardizing braking capacity and vehicle driving stability.

NOTE: With the vehicle ready for the road (conversion completed) the difference in
weight between the right side and left side must not exceed 100 kg, to prevent problems
with vehicle geometry.

These limits are defined in compliance with national and international standards (e.g. EU
Directives on braking), or are required by FIAT CHRYSLER AUTOMOBILES S.p.A. to assure
good vehicle dynamic behavior (e.g. transverse stability in motion).

Full functionality of ESC system is assured when those limits are respected.
 

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A high vent loop is your best solution. We have one in our vent hose. Height from the top of the tank to the top of the loop is about a foot. We have never noticed slosh-out from the vent, even with a full tank.

We have a 40gal fresh tank, plus a 6.5gal HW tank and 5 AGMs, all directly over the rear axle. The weight is fairly well balanced side-to-side. All that weight has been much less of an issue than I expected. But we also have a 3500-ext with the extra-HD sway bar. We only feel the weight in terms of power and acceleration, but it isn't real bad. We'd do it again for sure.

:sneaky:Also, do yourself a really big favor and get one of these bilious babies at Tractor Supply. Beats messing with hoses much of the time.
 

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Hi,
Another thing to bear in mind is securing the tank so it stays in place in a crash.

A 30 g forward crash will make that 300 lb tank and water "weigh" almost 10,000 -- so, 10,000 lbs trying to rip the tank off its mountings to join you in the cab.

Gary
 

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Another thing to bear in mind is securing the tank so it stays in place in a crash.
A 30 g forward crash will make that 300 lb tank and water "weigh" almost 10,000 -- so, 10,000 lbs trying to rip the tank off its mountings to join you in the cab.
Good point, Gary. We enclosed our monster in a unistrut cage with many bolts through the floor. No guarantees but at least we feel we did the best we could. Photos in our build thread.
 

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I think I have that same fill port, but I havent installed mine yet. What a great idea to put it horizontal like that. Question: What hose did you use from the fill port to your tank and how did you attach the half inch braided tube to the vent port?
The fill hose was a stiff spa type hose I found at Lowes, I took the fill port into Lowes and made sure I could slip it on (a blow dryer to heat it helps). I had to use a rubber connector for the fill port on the tank since it was so stiff and such a short distance. There is an adapter that I just screwed into the tank, believe it was the same thread as the tank and almost the same outside diameter as the stiff fill hose. For the vent hose I also just slipped on to the fill port and at the tank again found an adapter that would screw into the existing vent thread port. Then you can just slip the vent tube on the adapter. If you cannot get the thread to match the tank, you can carefully drill a slightly smaller hole near the ports and thread it in and caulk it.
61569
 

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Discussion Starter #14
Hi,
Another thing to bear in mind is securing the tank so it stays in place in a crash.

A 30 g forward crash will make that 300 lb tank and water "weigh" almost 10,000 -- so, 10,000 lbs trying to rip the tank off its mountings to join you in the cab.

Gary
I'll be making a unistrut cage as well and will make sure my beneficiaries and insurance are up to date. I'll keep the speeds under 5mph for added safety. I don't think any thing we can make for the van would withstand that kind of force. Definitely food for thought on building techniques.
 

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Hi,
Its not as formidable as it sounds.

A regular run of the mill seat belt will hold a 200+ lb person in a 30+g crash.
A single garden variety 3/8th bolt will hold 4000+ lbs -- but only if it does not pull out of the sheet metal floor or the tank support structure. If the support structure for the tank is well designed and has good load paths to the floor and sidewall it will not cut lose in a 30 g crash.

Gary
 

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The fill hose was a stiff spa type hose I found at Lowes, I took the fill port into Lowes and made sure I could slip it on (a blow dryer to heat it helps). I had to use a rubber connector for the fill port on the tank since it was so stiff and such a short distance. There is an adapter that I just screwed into the tank, believe it was the same thread as the tank and almost the same outside diameter as the stiff fill hose. For the vent hose I also just slipped on to the fill port and at the tank again found an adapter that would screw into the existing vent thread port. Then you can just slip the vent tube on the adapter. If you cannot get the thread to match the tank, you can carefully drill a slightly smaller hole near the ports and thread it in and caulk it.
View attachment 61569
I just went and checked at home depot and found these spa tubes, like the one in your picture, and they said they aren't safe for drinking water. Just a heads up. I ended up getting some braided tubing thats 1 1/2" ID.
 

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Hi,
Another thing to bear in mind is securing the tank so it stays in place in a crash.

A 30 g forward crash will make that 300 lb tank and water "weigh" almost 10,000 -- so, 10,000 lbs trying to rip the tank off its mountings to join you in the cab.

Gary
Yeah, I'm still trying to figure this one out. I've got 2 ratchet straps going horizontally, the top strap is bolted to the main cross beam with D rings (the same D rings that came out of the floor), and the bottom strap just bolted to D rings in the plywood. I'm hoping that top strap is enough to hold it in place during a crash. You can see the straps in the picture below.
61593
 

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Good point, Gary. We enclosed our monster in a unistrut cage with many bolts through the floor. No guarantees but at least we feel we did the best we could. Photos in our build thread.
Hi, why didn't you post the "final version" of your van's interior? And the second thing, do you have a rv or something? You seem to be an experienced DIYer and I was looking for someone to explain to me how to install a water tank for the toilet and bathroom. Sorry if I'm wrong and you are not the one who could help
 
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