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Old 03-27-2014, 05:12 PM   #1
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1969 25' Tradewind
Cypress , Texas
Join Date: Mar 2014
Posts: 20
Flush valves for the black water lines.

When upgrading to PEX I found the plumbing on my 1969 Airstream to be quite interesting and even a bit perplexing a couple of times. One item that I haven't quite wrapped up yet is what appears to be the drain point for winterizing. I'd like to use this for dual purposes I want to use it as a sewage hose fresh water flush to run fresh water through the hose to clean out the unpleasantries. I'm not keen on allowing a contamination point into my potable water system but don't want an extra hose to make it work. Could I finish this off with a check valve in addition to my manual flush valve and still stay sanitary with it permanently hooked up?

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Old 03-27-2014, 05:52 PM   #2
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1975 31' Sovereign
Palomar Mountain , California
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Would not mix the two systems - never!
I, and most others I know use a backflush system to clean out tank. You but a short couple (clear) that you put between the dump outlet and your flex pipe to the sewer that has a hose connection built in - any trailer store carries them. First you empty the black tank than hook up a hose to the backflush connection and backflush water under hose pressure back into the tank - this cleans the tank real well.
Don't ever let drinking water get near anything with poop in it - guaranteed trip to Doctor - and not fun. Saw this overseas in third world countries, really bad.

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Old 03-27-2014, 06:20 PM   #3
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1991 34' Excella
Princeton , New Jersey
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Don't even think about this.

If you have a 2 tank sewer system just drain the black water tank first and then while you lift the drain hose above the valve open the gray water tank and count to 10. Close he gray water tank and drop the hose. This sends a slug of gray water back into the black water tank and once you drop the hose it flushes the tank and the hose. After that second flow stops close the black water valve and then open the gray water valve and drain that tank.

Anything other than that is a waste of time. There are those that think flushing the hose or tank with water might make them clean but they are just kidding themselves.

Some will take exception to my comments but until they have removed or repaired a tank they will have no idea of what is in there.
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1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles

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Old 03-27-2014, 07:57 PM   #4
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1969 25' Tradewind
Cypress , Texas
Join Date: Mar 2014
Posts: 20
I tend to agree with not mixing the two just wasn't sure how to flush the hose with out connecting clean water to it. The attachment mentioned was what I planned to run the short hose to. I've only got one tank back there so using the grey tank to flush is out. I'm only trying to flush the hose before storage so how do y'all do it without using fresh water to do it? I also have no misconceptions that the hose is actually clean after flushing it nor do I think mixing the contents of my tank with my potable water is a good idea. The attachment I was looking at connects between the dump valve and my hose and threads a hose to it allowing city water to flow through it. I was looking to make a short hose from an outlet installed in the bumper compartment hooked up to that attachment. Is there a length of hose y'all do consider safe and if you say you only hook it up to the city water I just assume every connection at every park is contaminated, which is why I would never drink anything from my freshwater tank anyways. I planned to hook a ceck valve up at the adapter regardless of where I get the clean water.
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Old 03-28-2014, 06:56 AM   #5
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2012 Interstate Coach
Metairie , Louisiana
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Originally Posted by Sardog View Post
I'm only trying to flush the hose before storage so how do y'all do it without using fresh water to do it?
You disconnect it from the black tank, and run water in one end while the other end is still down the opening at the dump station. Most dump stations have a water source, usually labeled "Non-potable," with a hose already attached. Often the hose will be lacking a male fitting on the free end, so that it's not even possible to connect it to your municipal inlet.

Don't forget to rinse the outside of the hose as well; and hose down the area around the dump station drain to wash any residue that ended up on the pavement instead of down the drain.
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Old 03-28-2014, 08:55 AM   #6
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1969 25' Tradewind
Cypress , Texas
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Posts: 20
Roger that. I'll just keep a crappy extra hose then or hope for a well prepped dump station. The outlets will remain a drain only then.

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