Black tank flush system

[arl242]

We just brought home our new 2021 Hideout last week. I was checking things over last night getting ready for our trip this weekend and found that one of the blackwater flush systems does not work. I left the water on for 15 minutes and nothing came out of either tank. Everything worked fine on the other tank. I checked the fresh water level to make sure the water lines didn't get crossed up but nothing changed there either. Any suggestions besides having to take it to the dealer?

[93stpd1]

We just brought home our new 2021 Hideout last week. I was checking things over last night getting ready for our trip this weekend and found that one of the blackwater flush systems does not work. I left the water on for 15 minutes and nothing came out of either tank. Everything worked fine on the other tank. I checked the fresh water level to make sure the water lines didn't get crossed up but nothing changed there either. Any suggestions besides having to take it to the dealer?



I had a black tank valve handle break on mine. It was a black tank only no gray. I put a bolt on valve at the pipe end and eliminated the broken handle. If he can’t get parts it may be an easy quick fix till the parts come in. It would be a pain in the rear because you would be dumping often if it’s a shared discharge valve with your gray.

[arl242]

The black tank valve handle isn't broken as I shut it, ran water into the tank, opened it and it drained. Thank you though!

[93stpd1]

I’m sorry, that post was supposed to go on another post. Lol. Actually those flush fittings have a check valve in it. I’ve seen them go sour. Maybe try to blow it out with compressed air , put a hose on it then a blow out plug on the hose end and try to push air through or jack up the water pressure to open that check valve.

[arl242]

I will give it a try!

[chuckster57]

More often than not, the anti siphon valve is plumbed backwards.

[pikespeakviewer]

Could you hear water going into the tank?

[sourdough]

I'm not sure I understand what your problem is but I think your saying the black tank flush is not putting water into the black tank??? If so, Chuck is right. Chances are it is the anti siphon valve backwards. Look under your bathroom sink for the line going to the black tank flush. There should be an elevated portion with a little black cap on one side of the elevated pex.

[ChuckS]

If it were mine I’d either remove the plastic junk anti siphon valve completely or not even bother with the built in black tank clean out OEM junk... I use a valtera external with its own gate valve and see thru pipe... have for many years... I can clean out all tanks, know they are clean and don’t have to fret about flooding my fifth wheel because of a cheap plastic valve

[ewbldavis]

X3 on check valve - EASY fix.

Boneheads at factory put both of mine in backwards - good thing I paid CW $1000 to NOT fix it:nonono:

[notanlines]

Chuck, I hope you're not talking about this Flush King valve assembly: https://www.campingworld.com/flush-king-20522.html?gclid=EAIaIQobChMI2cGi-Y-m6wIVE9bACh1zAAGPEAQYAiABEgIl2PD_BwE&gclsrc=aw.ds
Other than the valve itself, the flush claims are bogus as a football bat.

[Brantlyj]

By chance did you screw your hose into the city water connection?
On my Hideout it is directly about the flush connection. Not paying much attention my first time I screwed the hose in the wrong port and stood there like an idiot wondering why no water was coming out the drain either.

[travelin texans]

Chuck, I hope you're not talking about this Flush King valve assembly: https://www.campingworld.com/flush-king-20522.html?gclid=EAIaIQobChMI2cGi-Y-m6wIVE9bACh1zAAGPEAQYAiABEgIl2PD_BwE&gclsrc=aw.ds
Other than the valve itself, the flush claims are bogus as a football bat.

I used one to rinse my hose not the tank. With a couple 90s from the outlet back to the tank that device had absolutely no tank rinsing effect what so ever, but worked to rinse the last foot of the drain line & the hose.

[IMASAP]

I've seen elsewhere online, where there was a kink in the line for the flush and the owner had to install a 90 in the line to get rid of the kink. During assembly, they simply made too sharp of a bend in the line. Fortunately, it was right under the bathroom sink and easily accessible.

[Javi]

One of the very first things I do when I buy a new trailer with the tank flush is to remove the anti-siphon / backflow preventer and replace it with a simple 90 degree fitting.. They I use a hose bib anti-siphon/backflow preventer on the water hose I dedicate to that task..

Then I never have to worry about the DW screaming bloody murder at me for the bathroom floor being flooded by the $0.50 piece of cheap Chinese plastic..

[arl242]

I appreciate all the thoughts and ideas, I will take them all into consideration and see what I come up with. I never heard water filling the black tank when the hose was hooked up and no, I didn't hook up the hose to the city water connection by accident, but can see how one could do it.

[flybouy]

It seems that those backflow preventers are commonly installed backwards. Don't know why, or how, maybe they said install the line to the tank on the left side and one guy is standing on the road side and installs the line forward and the next guy stands on the curb side and installs it aft.

In either case, as was stated, I don't trust that junk fitting so using a vacuum breaker on a dedicated flush hose makes sense to me as well.

[sourdough]

One of the very first things I do when I buy a new trailer with the tank flush is to remove the anti-siphon / backflow preventer and replace it with a simple 90 degree fitting.. They I use a hose bib anti-siphon/backflow preventer on the water hose I dedicate to that task..

Then I never have to worry about the DW screaming bloody murder at me for the bathroom floor being flooded by the $0.50 piece of cheap Chinese plastic..



^^^^This is what I did on the last trailer and will do on this one, just haven't had time yet.

[travelin texans]

One of the very first things I do when I buy a new trailer with the tank flush is to remove the anti-siphon / backflow preventer and replace it with a simple 90 degree fitting.. They I use a hose bib anti-siphon/backflow preventer on the water hose I dedicate to that task..

Then I never have to worry about the DW screaming bloody murder at me for the bathroom floor being flooded by the $0.50 piece of cheap Chinese plastic..

I also removed the anti siphon, but instead of the back flo preventer, which leak every time you release the pressure, I added a short water hose shut off valve on the flush port, IMO worked better that the bfp.
This setup also seemed to me to have more pressure on the flush line than with the anti siphon or the bfp.

[rbrdriver]

If you put in a 90 degree fitting in place of the backflow fitting does it really matter that you don't have said fitting anywhere in your hookup? I'm sure there is a code somewhere that says you should, but who's to know? Just saying.......

[JRTJH]

If you put in a 90 degree fitting in place of the backflow fitting does it really matter that you don't have said fitting anywhere in your hookup? I'm sure there is a code somewhere that says you should, but who's to know? Just saying.......

The problem is not "who's to know?" Rather it's, "If things go south and you have a siphon of black tank contents, could it/will it contaminate the entire campground fresh water system?".... That, should it happen, is, in a limited way, the same as the Flint public water debacle.....

You really don't want to be identified as the "code violator who contaminated the KOA".... http://www.sherv.net/cm/emoticons/hand-gestures/fingerwagging-smiley-emoticon.gif (http://www.sherv.net/)

[rbrdriver]

Point taken. I assume there is an anti-siphon valve I can insert in my water connection to the flush out system should I have to remove the one in the coach for some reason.

[JRTJH]

There are many styles. Here's one type that will connect between the black tank flush fitting on the side of your trailer and the dedicated hose you use to flush your black tank: https://www.amazon.com/Mueller-108-904RP-Backflow-Preventer-Vacuum-Breaker/dp/B07CZNVNSK/ref=sr_1_17?crid=2OWRPV23ARAV9&dchild=1&keywords=anti+siphon+hose+bib&qid=1598110873&sprefix=anti+siphon+%2Caps%2C205&sr=8-17

[travelin texans]

There are many styles. Here's one type that will connect between the black tank flush fitting on the side of your trailer and the dedicated hose you use to flush your black tank: https://www.amazon.com/Mueller-108-904RP-Backflow-Preventer-Vacuum-Breaker/dp/B07CZNVNSK/ref=sr_1_17?crid=2OWRPV23ARAV9&dchild=1&keywords=anti+siphon+hose+bib&qid=1598110873&sprefix=anti+siphon+%2Caps%2C205&sr=8-17

This is the type I mentioned in post #13 that tend to leak once hose pressure is released til it closes.
I'm no rocket scientist but on my 5th wheels the anti siphon was 4'+ straight up above the black tank then dropped that far straight to the outside connection, I've siphoned enough gas to know that's a helluva vacuum to get that siphon started.
I do understand the reasoning for it, but the odds of it happening in the RVs I've owned would be slim to none.

[JRTJH]

This is the type I mentioned in post #13 that tend to leak once hose pressure is released til it closes.
I'm no rocket scientist but on my 5th wheels the anti siphon was 4'+ straight up above the black tank then dropped that far straight to the outside connection, I've siphoned enough gas to know that's a helluva vacuum to get that siphon started.
I do understand the reasoning for it, but the odds of it happening in the RVs I've owned would be slim to none.

That's why I said, "If things go south....." Sure, I completely agree with you, chances of it happening are extremely remote" but it's a possibility (however remote) just like "they said" it'll never reach 100F in northern Michigan, but, last year, 3 days and so far this year 2... So, "never happens" does, at times, happen.....

Think about the guy that pressurized his black tank and it was coming up the toilet, pushing past the ball valve into the bowl... If he'd have quickly turned off his water, what kind of pressure "could have been" in that hose without a backflow preventer ??? Like I said, "a perfect storm situation" but not an "impossible situation".....

I'm seeing more and more campgrounds with "backflow preventers" on their fresh water faucets. I'd suppose they aren't there because they wanted to spend money on something that could be easily stolen... I'd suspect they're there because they don't want someone with a "modified black tank flush system" connecting to their campground fresh water system and "taking the risk that their missing anti-siphon valve under the sink won't make a difference"....

Not sure if it's one in a thousand, one in a hundred thousand or one in a million.... Really, if it happens to me, it's "one too many"....

[Javi]

If you put in a 90 degree fitting in place of the backflow fitting does it really matter that you don't have said fitting anywhere in your hookup? I'm sure there is a code somewhere that says you should, but who's to know? Just saying.......
I'm a Texas redneck wasn't worried about the code.... I just figured that a $5 vacuum breaker wasn't going to break the bank and might prevent a mess that I'd feel compelled to clean up... 😁

[Papa of 7]

Yes, mine is installed backwards, I am not going to use it. My question is the flush attachment with a 45 or 90 degree wash that attaches to the blackwater pipe, is there a better one and should it be with a gate valve or without. Tell me your thoughts!

[JRTJH]

Yes, mine is installed backwards, I am not going to use it. My question is the flush attachment with a 45 or 90 degree wash that attaches to the blackwater pipe, is there a better one and should it be with a gate valve or without. Tell me your thoughts!

I think you're asking about the "terminal connection type flush device" ???

IF so, depending on the number of 45 or 90 degree fittings that connect that fitting with the black tank outlet, any "flush device" that claims "high pressure water from the hose fitting into the black tank" will fail to produce that high pressure spray into the black tank. Each of those bends/elbows in the 3" outlet pipe will reduce the "spray" to a "influx of water" into the black tank. Essentially, the bends in the outlet pipe reduce the "flush device" to a "fill and dump device".... They are good for rinsing the black tank (by diluting the black tank contents) but they don't provide for any "water spray that hits the black tank sidewalls".... All of those "bends in the outlet" from the place where you add on that flush device back to the black tank entry opening, make for "no spray reaching the black tank interior walls"...

Now, if you've got a "straight shot of 3" PVC pipe from the outlet fitting to the tank outlet" and it's not "too long of a pipe" you might get some "water spray directly on the wall opposite the tank opening"... The other three walls, there's no way to "bend the spray to clean the tank interior".....

[Reider98]

Guarantee they installed it backwards. They did it to my 2020 Cougar. Very common problem. :banghead: You would think the factory would have addressed this problem. Good luck.

[analogkid]

Had the exact same issue on my 2020 Sprinter. Called the dealer and before I could finish describing the problem the lady helping me laughed and said “sounds like another with the check valve installed backwards”. I took it in and big shock - it’s exactly what was wrong. Sounds like this is VERY common.

[Papa of 7]

Looks like I will modify it was something better as someone mentioned previously.

[jimborokz]

This is the type I mentioned in post #13 that tend to leak once hose pressure is released til it closes.
I'm no rocket scientist but on my 5th wheels the anti siphon was 4'+ straight up above the black tank then dropped that far straight to the outside connection, I've siphoned enough gas to know that's a helluva vacuum to get that siphon started.
I do understand the reasoning for it, but the odds of it happening in the RVs I've owned would be slim to none.

I use this device on my black tank flush line, but I put it at the spigot end of the hose. That way I don't get sprayed on when I shut it off. And that 10' length of hose is used only for the tank flush and never anything else.

[Javi]

This is the type I mentioned in post #13 that tend to leak once hose pressure is released til it closes.
I'm no rocket scientist but on my 5th wheels the anti siphon was 4'+ straight up above the black tank then dropped that far straight to the outside connection, I've siphoned enough gas to know that's a helluva vacuum to get that siphon started.
I do understand the reasoning for it, but the odds of it happening in the RVs I've owned would be slim to none.

They don't TEND to leak, they are designed to leak... :D

That's how they break the suction...

Many campgrounds I've visited have these installed at the spigot with the set screw broken so it can't be removed.

[flybouy]

This is the type I mentioned in post #13 that tend to leak once hose pressure is released til it closes.
I'm no rocket scientist but on my 5th wheels the anti siphon was 4'+ straight up above the black tank then dropped that far straight to the outside connection, I've siphoned enough gas to know that's a helluva vacuum to get that siphon started.
I do understand the reasoning for it, but the odds of it happening in the RVs I've owned would be slim to none.

Don't want to argue but here's the difference between "sucking on the end of a hose" and having the hose filled to begin with. At sea level a siphon will work up to about 30' depending on barometric pressure. So if the hose is flowing water to the tank and the water line breaks somewhere lower then the tank then it can easily suck the tank contents back into the hose and pipe.

Think of it this way, let's say a 2" main breas 100 feet away. In effect, that area of pipe from that hose/tank (if it's the only place for air to enter) would effectively be the same as a piston of that area drawing the water back like a syringe in a vein.

I have a small pond in the back yard that I drain and clean every spring. I used an old pond pump to drain it until it died. After it died I use a 10' hose to drain it. The "deep end" is several feet deep. I just place the entire hose in the water, cover the end I'm going to take out with my thumb, then remove my thumb when the I get the end of the hose lower than the bottom of the pond. Atmospheric pressure does the rest.

[reelfun]

Water lines Crossed under Sink check and follow all lines.

[Whitewolf]

I probably use just about the same thing as Danny of the Travelin Texans use. Just the other day I noticed water dripping into the basement below the bathroom sink from the valve. That's our second valve and it'll be gone soon.