Water Tank 101

ChopperBill

Well-known member
Seems to still be lots of posts on the unfulfillable or short gallonage water tanks of about every model. This is a sloppy sketch of how I fixed mine even though it has be discussed before. In stock form if you are not perfectly level or tilted to the pump side you have virtually no chance in filling the tank to capacity. I upped those odds buy "shimming up" the opposite side of the pump intake as illustrated. Filling the tank requires all vent shut offs open. When you fill the tank the V3 vent, down hill side, will start to over flow first. Shut it off when it does. Then the V2 and the V1 in that order. Now you have a FULL tank! Probably more water than what the specs say. Dont fear as I have installed the center tank support to keep it in place. Keep all vents closed while you travel to keep water from siphoning out. The tank fill has its own vent, not shown in the illistration, for when you start using the water at your location. I think some of the newer units have run all three vents into one so you will have to deal with that when you have the tank uncovered and are "shimming" it up. It is not that hard of a project. Be aware that the 1/3 sensor is almost at the same level as the pump intake, so you will probably still show 1/3 tank when it is running out of water. If you leave the tank drain open while heading home the last of the water, very little, will drain and then you will show an empty tank.
Believe me if you are a boon docker this system works! Conserve on long trips or water at will on short stays.

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Uncle Rog

Well-known member
Howdy r4f, my fix was about the same except I had the shop plug the low side vent and paired the other two to drain in the original configuration by the ODS tires by the gravity drain. We left the last one alone that vents at the UDC. I use a simple garden hose meter when filling and keep the vent open. When it goes off I close it and turn down the pressure, I can put 7-8 more gallons in to get to the 75 gallon mark. The tanks will hold 75 gals, not 65 + the water heater. When we get set up we keep the vent closed until we use up some of the water, otherwise it would siphon out the entire tank! I discovered this at home luckily. This is the bigest tank we have ever had and it is GREAT not to have to mess with re-filling in the middle of a trip.

Note: I turn down the pressure at the end of the fill so as not to risk blowing out the tank by over pressurizing it, believe me it is full...........
 

lhetsler

Well-known member
Filling fresh water tank

I solved this problem myself after one attempt by the dealer to fix it. That lasted 2 weeks. I bought one of those rubber attachments that have rubber on one end that is made to stretch over a water faucet that does not have threads, the other end has regular hose threads, which I hook a hose up to. I push the rubber side into the filling port which seals it off and when I run water into the tank, it creates enough pressure to push the water that gets in the vent hoses out, clearing the vent line. I know I could tear into the bottom of the unit and fix it right, but using this little device, it is not an issue. I have gone a full 9 days on a tank of water, even taking quick showers (using the wet down, shut off, wash, and then rinse method). This is with 3 people in the unit. Prior to using this method I could never get more than two thirds of a tank worth of water.

One thing to be carefull of is to listen to the vent and when you no longer hear air coming out you know you are getting close to full. I alway stay right there with the hose when I fill the tank. This setup does not allow a great deal of pressure because when the tank is full water will push by the rubber end to let you know the tank is full.
So not a chance that you would damage the tank. You never want to pressurize your fresh water tank as that can damage it, but this setup is just enough pressure to clear the vent lines. I have been doing this for a year now with no issues.
 
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