Thank You Keystone.

[BookPaul74]

So after reading some posts I’m one of the lucky ones that appears to have the back flow valve installed wrong on the sewer flush out system. I’ve owned the trailer a little over two years and this is probably the first time I’ve been in an RV site for more than a night.

So after hooking it up and turning the water on, nothing. And the tap has plenty of pressure. I have one of those elbows with a flush out water connections but there’s two 45° fittings before a 90° into the tank. I have an extra shutoff valve for the end of the drain but figure it’s just going to fill the tank.

I had one of the toilet flush out wands for my first fifth wheel but when I got the Alfa it had two 45° fittings before the tank so I got rid of it. But with the Cougar 337fls having a mid bathroom, it’s a straight drop into the tank so guess I’ll be getting a new wand.

[sourdough]

For a quick check find it (under bathroom sink?) and see if it's backwards. There will be an arrow on it indicating the direction of water flow. If it is backward, which it well could be, just unscrew it and turn it around for the short term. After checking/fixing it either replace it with a brass one or just put in 2 90 degree sharkbite connectors and a short piece of pex to eliminate it. If you eliminate it put a backflow preventer on the end of your black tank flush hose.

[travelin texans]

Turn the valve around or replace it with 2 90s then the flush line would work.

[BookPaul74]

The lines for the sink go into the wall. When I pulled all the electrical out I could see the water lines for the bathroom and kitchen. If I get ambitious I just might go hunting. It has a mid bathroom and a rear bedroom.

[sourdough]

Have you looked in the bathroom sink cabinet up high? You can hope it's there because the others I've seen just get progressively worse. You can look behind the convenience center (if that's where the flush connection is) and trace that line if it's not under the bath sink. It could be in the wall behind the shower faucets or ?? All of mine have been under the bathroom sink. I had a friend with a Big Horn have his start leaking water. The mobile tech ended up cuttion a portion of his basement wall out? Why I never figured out but he said it was "up" inside that wall. Wherever it is you'll have 2 white or blue pex water lines going up into that little black device.

[JRTJH]

The easiest and simplest way to determine if the Anti-siphon valve is under the bathroom sink is to open the vanity door and count the PEX lines. If there are 4, then the anti-siphon valve is attached to the top of two of them. If there are only two PEX lines, then the anti-siphon valve is located somewhere else.

Usually the hot PEX lines are red and the cold PEX lines are blue. "Undesignated hot/cold lines" are often white. My anti-siphon valve is plumbed with white PEX. Under my vanity are one red, one blue and two white PEX lines.

[BookPaul74]

Originally Posted by sourdough

Have you looked in the bathroom sink cabinet up high? You can hope it's there because the others I've seen just get progressively worse. You can look behind the convenience center (if that's where the flush connection is) and trace that line if it's not under the bath sink. It could be in the wall behind the shower faucets or ?? All of mine have been under the bathroom sink. I had a friend with a Big Horn have his start leaking water. The mobile tech ended up cuttion a portion of his basement wall out? Why I never figured out but he said it was "up" inside that wall. Wherever it is you'll have 2 white or blue pex water lines going up into that little black device.

That’s what I’m going to have to do once it cools down. There’s only two flex lines going through the wall where the drain pipe is.

[BookPaul74]

Originally Posted by JRTJH

The easiest and simplest way to determine if the Anti-siphon valve is under the bathroom sink is to open the vanity door and count the PEX lines. If there are 4, then the anti-siphon valve is attached to the top of two of them. If there are only two PEX lines, then the anti-siphon valve is located somewhere else.

Usually the hot PEX lines are red and the cold PEX lines are blue. "Undesignated hot/cold lines" are often white. My anti-siphon valve is plumbed with white PEX. Under my vanity are one red, one blue and two white PEX lines.

There’s just the pre made flex hoses that you see underneath the residential sink. When I pulled the electrical box out to upgrade the charger and run the solar wiring I saw a lot of water line from the bathroom sink, the kitchen sink and the red and blue pex hoses coming up from the floor. I’ll do some chasing when it cools in Arizona. But if it’s underneath the floor and under belly it go to stay the way it is.

The connections are for the city water hookup and a separate one for the sewer flush. So when I feel ambitious I’m pulling stuff out of the storage so I can check the connections and look for the check valve.

[flybouy]

The anti-siphon valve will be higher than the toilet. If it's not inside a cabinet it may be inside an interior wall. Some units have them behind the shower wall where the faucets are. Typically it won't be too far from the exterior hose connection is located for the blank tank flush.

[BookPaul74]

Originally Posted by flybouy

The anti-siphon valve will be higher than the toilet. If it's not inside a cabinet it may be inside an interior wall. Some units have them behind the shower wall where the faucets are. Typically it won't be too far from the exterior hose connection is located for the blank tank flush.

There’s a access cover on the front edge of the shower pan, I figure it’s for the drain pipe. I’ll have to look to see if there’s any kind of access cover for the shower facet.

I’m guessing it’s going to be behind the panel for the other connections or behind the wall where the plumbing is for the bathroom and kitchen.

[sourdough]

The anti siphon won't be low. It has to be high so black water can't back up, that's the reason there is a high loop.

[BookPaul74]

Originally Posted by sourdough

The anti siphon won't be low. It has to be high so black water can't back up, that's the reason there is a high loop.

OK behind the shower faucet or behind the wall.

[RickV]

I haven't looked on this new 5ver but, on the old one it was behind a linen/towel closet next to the shower. There was a part of the paneling that had been cut and screwed in. Once that came off the valve was around a corner where you couldn't see it. Had to use an endoscope to replace it. I just did the two 90 degree elbow thing when it started leaking.

[ChuckS]

Once you locate the factory anti siphon valve yank it out and place it in the trash.. it is a major source for water leaks and had odors

Either until the two lines together with a shark bite union OR spend the bucks and replace that valve with a quality brass one

If you remove the valve completely..which is what I would do then you eliminate one more thing to worry about regarding water leaks..

On my RV I have never used the black tank flush in nine years.. I use a Valtera Kong Flush permanent installed on sewer outlet line..

Two benefits are a separate gate valve so I don’t get crap on my feet when I take the sewer cap off and I can flush all holding tanks..

My sewer drain line is a straight shot to each of the 3 holding tanks so the King flush works great

[BookPaul74]

Originally Posted by ChuckS

Once you locate the factory anti siphon valve yank it out and place it in the trash.. it is a major source for water leaks and had odors

Either until the two lines together with a shark bite union OR spend the bucks and replace that valve with a quality brass one

If you remove the valve completely..which is what I would do then you eliminate one more thing to worry about regarding water leaks..

On my RV I have never used the black tank flush in nine years.. I use a Valtera Kong Flush permanent installed on sewer outlet line..

Two benefits are a separate gate valve so I don’t get crap on my feet when I take the sewer cap off and I can flush all holding tanks..

My sewer drain line is a straight shot to each of the 3 holding tanks so the King flush works great

If I find it I’ll use a metal one. I’m wondering if where you screw the hose on if it isn't a one way check valve? I’ll take a photo of the water hookup panel.

I have a 45° with the hose attachment and a check valve and a extra gate valve. As I explained from the end to the tank there’s 2 45° at a 90° so even though I have a lot of water pressure it’s just going to back fill the tank and not have a powerful stream of water to blast poop out.

I generally do a lot of boondocking and I modify the two sewer connections to raise them up. I gained several inches on the front kitchen drain and just a bit on the rear. The rear one I found scrape marks on the cap bottom. So I really don’t want stuff hanging off.

Lazy man fix Toilet Wand.

[rlh1957]

My ‘20 Cougar Half Ton 29RKS was backwards.
Black tank flush wasn’t allowing water to go in. I had a in line flowmeter to monitor how much I was putting in. Nothing!
When I turn off faucet and disconnected hose, it was pressurized and water sprayed back.

Looked under bath room sink for back flow valve.
(I had followed the flush line in the pass through to see where it went and confirmed up to bathroom, then back down.)

Reversed the valve and tried again with flush success.

I suppose the assembler inside sees two blue PEX lines coming up and the vslve got put on backwards.

[PDMarlowe]

We have an older Outback 260FL that has the backflush system. We bought it used a few years ago and it worked fine until this year. Reading the threads I thought the valve may have gone bad or broke from a late winterizing so I replaced it. No difference. I'm afraid to put compressed air to it that might damage something else. Any thoughts?

[flybouy]

Originally Posted by PDMarlowe

We have an older Outback 260FL that has the backflush system. We bought it used a few years ago and it worked fine until this year. Reading the threads I thought the valve may have gone bad or broke from a late winterizing so I replaced it. No difference. I'm afraid to put compressed air to it that might damage something else. Any thoughts?

Check the and confirm the new valve is oriented in the proper direction.. there should be an arrow on it indicating the direction of flow. If it's connected properly then blow air thru the line connected to the tank. If it doesn't flow the the spray head in the tank is clogged. Try the easy things first like fliing/flushing the tanks using the GEO method, using a toilet wand. Etc. Do not use liquid plumber, draino, or other harsh chemicals.

[PDMarlowe]

Thanks Flybouy. Yeah, the first thing I checked was to make sure I put the new valve in correctly. Fortunately for me, the PEX lines are long enough that I could pull them out of the cabinet and work on it in my lap. I haven't used the trailer much in the last year because of various schedule conflicts and have only had the opportunity to fill and drain a couple of times. I will be going next weekend to a campground with full hookups and will take advantage of that to see if the nozzle will clear.

I really appreciate all of the people on this forum and the incredible amount of knowledge that all of you wonderful people are willing to share.

[travelin texans]

Originally Posted by PDMarlowe

Thanks Flybouy. Yeah, the first thing I checked was to make sure I put the new valve in correctly. Fortunately for me, the PEX lines are long enough that I could pull them out of the cabinet and work on it in my lap. I haven't used the trailer much in the last year because of various schedule conflicts and have only had the opportunity to fill and drain a couple of times. I will be going next weekend to a campground with full hookups and will take advantage of that to see if the nozzle will clear.

I really appreciate all of the people on this forum and the incredible amount of knowledge that all of you wonderful people are willing to share.

Before traveling next weekend add several gains of water & a big Ole giant dose, 1/2 a cup or more, of Dawn liquid down the toilet, the sloshing while traveling will help break down the crap (pun intended) in the tank. Once you arrive drain, fill, flush, repeat either with the flush line or a hose (not your drinking water hose) through the toilet, the tank repeatedly before too much use.