Black tank flush back flow valve

[howie70]

Factory back flow (or whatever its called) leaked. Replaced it with a nice brass one that was recommended on here. It leaks too.
I have read the discussions about these on here but I still don't understand why it is needed. My black tank flush line isn't tied into my fresh water plumbing in any way. The only way I see it could possibly flow back would be if the water hose was hooked to it, water cut off and black tank valve closed and somehow water was still entering the black tank. I am wondering why I can't just remove the valve.

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[howie70]

No thoughts or opinions on this?

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[fonzie]

Lots of people do remove it but usually do not admit it as it is a required device by RV regulation........if you remove you can always use one at the hose end....


Everbilt 3/4 in. Hose Bibb Vacuum Breaker-VACBFPZ4EB - The Home Depot

[northstar1960]

Originally Posted by howie70

Factory back flow (or whatever its called) leaked. Replaced it with a nice brass one that was recommended on here. It leaks too.
I have read the discussions about these on here but I still don't understand why it is needed. My black tank flush line isn't tied into my fresh water plumbing in any way. The only way I see it could possibly flow back would be if the water hose was hooked to it, water cut off and black tank valve closed and somehow water was still entering the black tank. I am wondering why I can't just remove the valve.

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it there for the slight chance of back flow into the water supply system !
i would dump the back flow and just get a check valve . no leak and no fuss and you'll be safe just in case that one in a million thing happens what ever that is

[DouglasReid]

Originally Posted by northstar1960

it there for the slight chance of back flow into the water supply system !
i would dump the back flow and just get a check valve . no leak and no fuss and you'll be safe just in case that one in a million thing happens what ever that is

the backflow preventers that are installed on your hose bibs at your house all also drip a bit of water every time they are turned off.

If it is located outside your RV and/or inside the water compartment on the outside it does no harm at all when this happens. The drip simply runs out the bottom or evaporates.

Their purpose is to prevent a siphon from forming and sucking contaminated water back into yoru rv system or the system at the park or house you are hooked up to.

My advise is to leave it installed. Your safety and teh safety of others could easily be at stake!

[itat]

Northstar is correct. It's job is to prevent contamination of the source water i.e. the campground's water system that supplies all the sites.

I use the little brass one that Fonzie provided a link to. The previous owner of my TT removed the factory-installed plastic one and installed a plastic 90 degree bend in it's place. So I use the brass one on the end of my dedicated flushing hose.

If you opt to remove it, please do not hook up to your black tank flusher without some kind of backflow preventer/check valve on your hose. And don't use your white city water hose - get a dedicated regular garden hose for that job.

[Retired JSO]

I get strange looks when I break out an old white camp hose to flush my tank. Those giving me those looks probably don't see the several black spray painted areas along that hose. I am not going to throw away a good hose just because it's not the right color.

[NMWildcat]

Originally Posted by northstar1960

it there for the slight chance of back flow into the water supply system !
i would dump the back flow and just get a check valve . no leak and no fuss and you'll be safe just in case that one in a million thing happens what ever that is

X2

[howie70]

Originally Posted by DouglasReid

the backflow preventers that are installed on your hose bibs at your house all also drip a bit of water every time they are turned off.

If it is located outside your RV and/or inside the water compartment on the outside it does no harm at all when this happens. The drip simply runs out the bottom or evaporates.

Their purpose is to prevent a siphon from forming and sucking contaminated water back into yoru rv system or the system at the park or house you are hooked up to.

My advise is to leave it installed. Your safety and teh safety of others could easily be at stake!

Well this one drips inside my bathroom cabinet. That is unacceptable. And as far as contaminating my campers fresh water..... I say it can't happen. It is not connected any way shape or form to my fresh water system. I can see where there is a very very slight chance of back flow into the supply hose. Think I will go with Fonzie's recommendation.

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[northstar1960]

Originally Posted by DouglasReid

the backflow preventers that are installed on your hose bibs at your house all also drip a bit of water every time they are turned off.

If it is located outside your RV and/or inside the water compartment on the outside it does no harm at all when this happens. The drip simply runs out the bottom or evaporates.

Their purpose is to prevent a siphon from forming and sucking contaminated water back into yoru rv system or the system at the park or house you are hooked up to.

My advise is to leave it installed. Your safety and teh safety of others could easily be at stake!

The anti siphon hose bib on the house are not the same as in these RV's .
these should not drip or leak if they do they need replaced . if a siphon is created it should only allow air in to break the siphon

[northstar1960]

Originally Posted by howie70

Well this one drips inside my bathroom cabinet. That is unacceptable. And as far as contaminating my campers fresh water..... I say it can't happen. It is not connected any way shape or form to my fresh water system. I can see where there is a very very slight chance of back flow into the supply hose. Think I will go with Fonzie's recommendation.

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if it leaks it is either a loose connection or the diaphragm is not sealing well . check the threaded connection if none then it needs replaced these should not leak or drip

[ADVtraveller]

My factory installed Black tank flush on my 2012 Stealth 2714 toyhauler quit working last year. It won't take water when the hose is hooked up on the outside hose point. It's almost as if the line was capped off. When it worked, we could hear the sprinkler head in the black tank, but now.. nothing.

I've looked for the culprit and noticed the check valve unit as I was following the line from the outer hook-up to the tank. The check valve unit isn't leaking but I wonder if maybe its broken and stuck closed. I hope that it's not the problem because it's tucked up high behind the sink and will be nearly impossible to get to with removing my kitchen counter top. For what it's worth, mine appears to be a JR Products vacuum breaker / check valve as I matched pictures I found on Google.

My only other thought was that the sprinkler head itself is broken. I thought it might be clogged with TP but we never even get close to filling the black tank. And I ruled out the TP clog also because the line doesn't accept any water at all. As I said, it's like it's completely sealed or capped.

Any thoughts or suggestions would be greatly appreciated.
Thx

[northstar1960]

it could be the back flow or the nozzle is clog from debris from the hose . i would replace back flow first . it does need to be mounted higher then the intake . maybe just need to remove sink . can't say with out a few pictures

[hunterrick]

The back flow preventer on your black tank flush is not there to protect the fresh water supply of the camper, it is there to protect the source. If black water backed up into the source supply, it could contaminate the entire campground's fresh water system.