Siphon fresh water tank?

[Chip Arnold]

Is it possible to siphon the water out of the fresh water tank through the outside fill pipe? I can't find the fresh water tank drain on my 31' '76 International rear bath. The manual says there are three drains under the galley sink. There are none there. The h & c water lines go straight back from there to the trunk area and the only h & c water drains are the ones there in the trunk. It's very possible that this has all been re-plumbed in the last 33 years. In any case, I cant find a drain for the fresh water tank. Looking under the trailer I cant see anything there either. There is a square steel plate with a bolt in the middle under the center of the tank area. It's about 1' square. It's awful rusty and the bolt doesn't look like it would come out without a struggle. Before I break something I'd like to know what's behind that plate.

[overlander63]

Your drain should consist of a red faucet handle. There may be up to 3 of them in that area. Turn one at a time until water pours out onto the ground. No siphoning should be required.
If you absolutely can't get the tank to drain, just turn on the water pump, and run water into the sink, out the drain valve, until the pump starts running out of water. That will remove all but a couple of gallons.

[Chip Arnold]

There is definately no red faucet handle under the sink and no hole in the floor where one may have been in the past. Under the range (to the left of the furnace) is a hole in the floor through which the heat duct for keeping the tank warm goes. You can access the connection for the outside water fill tube there too. The rubber hose to the pump comes out here as well but it's impossible to get your hand in to where it connects to the tank. There is no sign of a drain valve there either. I doubt very much that tiis part of the floor has ever been messed with ........ It had orig. carpet and cabinets when I got it and all that would have had to be removed to work on the floor.

[ticki2]

On my '76 there was no drain valve for the water tank . You have to empty it with the pump . If you can get the steel plate off under the trailer you will find the other end of the pump hose where it connects to the tank . I cut this hose and installed a T with a drain valve , it's at the low point so you can fully drain the tank . Try soaking the bolt and plate edges with penetrating oil for a few days . Then try loosening and tightening the bolt back and forth , be patient , it may take a day or two . You can also try some heat on the bolt. The plate and bolt are also a center support for the tank , so not a good idea to run without it . Eventually you will need access to that area , most likely to change the hose , so it is worth the effort . The valves in the trunk are to drain the water pipes above the floor , they will not drain the water tank. Good luck

[ticki2]

One other thing , I think the valves under the sink are in a center bath , the rear bath has them in the trunk . I can't think of any reason you cannot siphon the water tank , however , I don't think you can completely empty it that way.

[overlander63]

Originally Posted by ticki2

One other thing , I think the valves under the sink are in a center bath , the rear bath has them in the trunk . I can't think of any reason you cannot siphon the water tank , however , I don't think you can completely empty it that way.

Those valves are in the kitchen of our 1974 Sovereign rear bath. They are in a hole in the floor between the frame rail and fresh water tank, at the edge of the furnace/water pump access door.

[ticki2]

Originally Posted by overlander63

Those valves are in the kitchen of our 1974 Sovereign rear bath. They are in a hole in the floor between the frame rail and fresh water tank, at the edge of the furnace/water pump access door.

Did you also have valves in the rear trunk ? The '76 service manual shows the locations as indicated above for the center and rear baths.

[Chip Arnold]

OK! I got the steel plate off under the tank and sure enough, there's the hose connection. Tomorrow I'll go get a T and drain fitting and put it in there. I'm going to run the bleach solution through it too as I have no idea when, if ever, it has been used. I just wish there was a little more working room but I guess it wouldn't be an Airstream if there was :-) Thanks everyone for the helpful answers.

[ticki2]

Originally Posted by Chip Arnold

OK! I got the steel plate off under the tank and sure enough, there's the hose connection. Tomorrow I'll go get a T and drain fitting and put it in there. I'm going to run the bleach solution through it too as I have no idea when, if ever, it has been used. I just wish there was a little more working room but I guess it wouldn't be an Airstream if there was :-) Thanks everyone for the helpful answers.

Use the front jack to lift it up , it will give you a bit more room underneath. Put it back down to drain . Also , do yourself a favor and replace that center bolt with SS.

[Distantdrummer]

Since the pump hose connects under the tank it seems the pump would empty almost all the water in the tank. (gotta figure the exit nipple is located in the lowest part of tank I hope). Someone above suggested a few gallons would not pump out. I wonder if this means some tanks did not drain from the bottom? I never saw an access plate under my old '74 or '75 amidships water tank area. (both rear bath mods) . I am trying to visualize how that noted 12" square plate supports the tank. Looks like when removed the tank would drop a bit. With water inside it would be a task to replace access cover if the tank dropped when support was removed.??
What am I overlooking here?

thanks

[ticki2]

Originally Posted by Distantdrummer

Since the pump hose connects under the tank it seems the pump would empty almost all the water in the tank. (gotta figure the exit nipple is located in the lowest part of tank I hope). Someone above suggested a few gallons would not pump out. I wonder if this means some tanks did not drain from the bottom? I never saw an access plate under my old '74 or '75 amidships water tank area. (both rear bath mods) . I am trying to visualize how that noted 12" square plate supports the tank. Looks like when removed the tank would drop a bit. With water inside it would be a task to replace access cover if the tank dropped when support was removed.??
What am I overlooking here?

thanks

Perhaps the '74 and '75 are different and don't have a center plate , I've not looked at one . I beleive it is a support , it certainly does't need a 1/2" bolt to hold an access cover on . perhaps it was added for '76 because there were problems in previous years , 50 gals of water is a healthy load.I did not say the pump would not empty the tank. My comment had to do with siphoning may not empty the tank.

[Chip Arnold]

The tank is a sort of square donut with a square donut hole in the middle.The hose is not coming straight out of the bottom of the tank but the bottom side of the donut hole. The donut hole is about 10" - 12" square. There is a steel boss coming down from the frame above the hole and the plate bolts to that providing support to the center of the tank. It is otherwise supported by the aluminum box it sits in and maybe other ways which I can't see from the bottom. There is fiberglass insulation above the tank and 1/2 inch styrofoam beneath it.

[Aage]

Here's a photo from the 1977 Service Manual of the water tank. it is indeed a square "doughnut".

It appears to be directly behind the entrance stairs.

[Chip Arnold]

Thanks, that's a great help. # 12 is the steel plate. There's not much room up in there to work. I went to the hardware today but didn't find anything to make a drain with. I'm going to look at an RV parts place on line tonight.