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Topic: By passed Black Tank Flush back flow preventer

Posted By: Atlee on 02/22/18 03:33am

The back flow preventer failed after 5 months of use. Was going to replace it yesterday, but @ $50, I decided no. Looked for a simple plastic elbow, but couldn't find one, so made a brass one. Also used a couple of strap hangers to help secure the flush tubing. Something that should have been done at the factory, IMO.

[image]

[image]
The broken piece is on the left. $50 The two brass pieces used to replace it are on the right. $13.15

[image]

[image]
I added strap hangers to help keep the top heavy long run of plastic pipe in one place.


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Posted By: Teacher's Pet on 02/22/18 04:54am

It doesn't have to cost $50 for the cheap plastic one ..go to Lowes Under $19 for a brass one, of course you'll need two 1/2" nipples. The system should function as designed without the horrible adverse effect inside your fresh water system.


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Posted By: JaxDad on 02/22/18 06:04am

You couldn’t pay me enough to remove a backflow preventer in a spot like that.

It’s illegal for a reason, because it’s potentially a deadly accident waiting to happen.

How much liability are you willing to assume for omitting a $20 part?


Posted By: agesilaus on 02/22/18 06:05am

When you all come down with gastroenteritis (or worse) you'll spend more than $50 not counting your lost time. That backflow preventer is not there for cosmetic reasons.


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Posted By: rhagfo on 02/22/18 06:17am

I would never use that without that back flow device!!!


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Posted By: Cummins12V98 on 02/22/18 06:40am

So you are willing to risk SERIOUSLY contaminating the RV parks water system??? These parks have lines break all the time and guess what that creates a pull on your water line potentially sucking SH!T into the parks water system.

Since you now know the serious risk YOU have created are YOU going to step up and replace your vacuum breaker with a new functioning unit????????


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Posted By: newlee on 02/22/18 07:16am

It is really hard to fix stupid.


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Posted By: CarnationSailor on 02/22/18 08:07am

I think the risk of not having a backflow preventer is being overstated.

A couple of years ago I had a question about my black tank flush system and called the company that made it. The owner and designer of the system happened to answer the phone (small company). Among other questions, I happened to ask him about all the failures I was reading about on this forum. He said his model had very few failures, but if mine failed, I should call and he would send me a replacement for free.

He also said that he believed a backflow preventer was completely unnecessary as long as the supply line rose at least 2-feet above the tank before dropping back down to the hose connection. He said there was no way a siphon could form with 2-feet of air above the tank. If mine should fail, he recommended that I just bypass it. (He included a backflow preventer in the kit because RV manufacturers wouldn't buy it otherwise.)

You can take this for whatever you think it's worth, but at least try not to beat up the OP so hard.


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Posted By: Matt_Colie on 02/22/18 08:08am

We don't know how far the OP's lash-up is above the waste tank.

What he obviously does not know is that a real backflow preventer is more than just a check valve. When pressure is not present in the inlet or is at the outlet (either case) the device opens a 2" air gap between the supply and the service.

But it will be safe for the community as long as he never attaches the system to the water supply and/or overfills the black tank.

Matt

* This post was edited 02/22/18 08:25am by Matt_Colie *


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Posted By: ScottG on 02/22/18 09:03am

This is probably the worst idea I have ever read about on this forum (and that's saying something).


Posted By: BB_TX on 02/22/18 09:07am

While remotely possible for a backflow to happen, the likelyhood of such an event is very very low. Would take a set of highly unlikely conditions for it to happen. As long as there is water pressure at the park faucet, it simply can not happen. If the shutoff valve to the flush connection was closed it can not happen. You could only get backflow if park water pressure were lost while you were in the process of flushing resulting in that loss pulling a vacuum on the water line. Even then the flush head would not be submerged in the black tank water and at most there could possibly be a bit of black water on the flush head. And then only if you had not yet actually run any water thru that head.

Having said that, many of us have removed those failure prone anti siphon valves, but have added an external anti siphon valve to the outside flush connection to maintain the integrity of the system.


Posted By: downtheroad on 02/22/18 09:08am

Teacher's Pet wrote:

It doesn't have to cost $50 for the cheap plastic one ..go to Lowes Under $19 for a brass one.

Follow this advice....it's a much better "mod."


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Posted By: drsteve on 02/22/18 10:36am

BB_TX wrote:

While remotely possible for a backflow to happen, the likelyhood of such an event is very very low. Would take a set of highly unlikely conditions for it to happen. As long as there is water pressure at the park faucet, it simply can not happen. If the shutoff valve to the flush connection was closed it can not happen. You could only get backflow if park water pressure were lost while you were in the process of flushing resulting in that loss pulling a vacuum on the water line. Even then the flush head would not be submerged in the black tank water and at most there could possibly be a bit of black water on the flush head. And then only if you had not yet actually run any water thru that head.

Having said that, many of us have removed those failure prone anti siphon valves, but have added an external anti siphon valve to the outside flush connection to maintain the integrity of the system.


The tank is vented, so the flush valve does not have to be open for backflow to take place.

I agree, the likelihood is still very low, but when you have millions of tank dumping events, it's going to happen.


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Posted By: old guy on 02/22/18 11:37am

we used to sell back flow preventers for a just a few bucks at our store. they screw right on to the hose at the TT entry in the out side wall


Posted By: Atlee on 02/22/18 01:14pm

Didn't mean to start a firestorm, but apparently I have.

A few answers or explanations.

1) I plan on getting a black flow preventer for my hose I used when dumping the black tank.

2) It sounds like some, if not most on here, believe I keep a hose hooked between the spigot at the camp site and the black tank flush system all the time. Never the case. I hook it up when I need to flush the tank.

3) It also sounds like some if not most here think I have a full black tank when hooked up. Not so. I dump the black tank, then hook up the hose to the flush system, and turn it on. I let it spray and dump at the same time, so there is no way "stuff" from the black tank can enter into the hose.

4) There is a vertical run of at least 3 feet before the black flush piping exits the rear of the trailer. The black flush connection on the rear of the trailer is nearly 4 feet above the ground.


Posted By: BB_TX on 02/22/18 01:35pm

drsteve wrote:

BB_TX wrote:

While remotely possible for a backflow to happen, the likelyhood of such an event is very very low. Would take a set of highly unlikely conditions for it to happen. As long as there is water pressure at the park faucet, it simply can not happen. If the shutoff valve to the flush connection was closed it can not happen. You could only get backflow if park water pressure were lost while you were in the process of flushing resulting in that loss pulling a vacuum on the water line. Even then the flush head would not be submerged in the black tank water and at most there could possibly be a bit of black water on the flush head. And then only if you had not yet actually run any water thru that head.

Having said that, many of us have removed those failure prone anti siphon valves, but have added an external anti siphon valve to the outside flush connection to maintain the integrity of the system.


The tank is vented, so the flush valve does not have to be open for backflow to take place.

I agree, the likelihood is still very low, but when you have millions of tank dumping events, it's going to happen.

Backflow means black water flowing backward into the public water source. And that can not happen unless you have the flush water valve open to run the flush. And then it can only flow backward if there is a loss of water pressure from the souce causing the water line to pull a vacuum on the line connected to it. As long as there is pressure at the public water source, that water can not flow backward valve open or not. Vent is immaterial.


Posted By: Old-Biscuit on 02/22/18 01:40pm

ATLEE.......ignore the nah-sayers.

Black Tank Flush System.
Anti=siphon vacuum breaker device is mounted at least 2' above the top of waste tank

Waste tank would need to be FULL and PRESSURIZED to florce flow from waste tank back thru Spray Nozzle, UP 2' then down into hose which would need to be connecged to a water supply system that has NO pressure in order to 'contaminate' the water supply system


Possible........sure

Probable............HIGHLY UNLIKELY

[image]


There is NOT a 'law' making it illegal to remove the device
RIVA requires it for RV MFG to use RIVA Seal on there products

A simple backflow preventer on the supply hose will do the same

[image]

ATLEE......
Common Sense is NOT lost [emoticon]


Is it time for your medication or mine?


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Posted By: DutchmenSport on 02/22/18 01:51pm

Don't feel too bad Atlee! I get beat up lots of times too on these forums... actually, so much, I don't post much any more! Good luck! Personally, I have no problems with what you did.

Want a real shocker? Price the cost of the seal in the bottom of your toilet bowl? That little piece of rubber cost me $42!


Posted By: Ralph Cramden on 02/22/18 03:01pm

Old-Biscuit wrote:

ATLEE.......ignore the nah-sayers.

Black Tank Flush System.
Anti=siphon vacuum breaker device is mounted at least 2' above the top of waste tank

Waste tank would need to be FULL and PRESSURIZED to florce flow from waste tank back thru Spray Nozzle, UP 2' then down into hose which would need to be connecged to a water supply system that has NO pressure in order to 'contaminate' the water supply system


Possible........sure

Probable............HIGHLY UNLIKELY

[image]


There is NOT a 'law' making it illegal to remove the device
RIVA requires it for RV MFG to use RIVA Seal on there products

A simple backflow preventer on the supply hose will do the same

[image]

ATLEE......
Common Sense is NOT lost [emoticon]



In addition any campground whose water supply meets code is going to have a backflow preventer on the connection itself like the one shown in your post. You may find them missing in some private parks, but I have yet to see a fed, state, or municipal managed campground without them.

I present to you the backflow police, a division of the weight police.


Posted By: buc1980 on 02/22/18 03:59pm

Old FW have the black flow preventer?


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Posted By: Old-Biscuit on 02/22/18 04:10pm

buc1980 wrote:

Old FW have the black flow preventer?



IF a Black Tank Flush System was FACTORY installed then YES it will have a anti-siphon vacuum breaker backflow device.

UNLESS previous owner removed it due to flooding/stink/failure of device


Posted By: Cummins12V98 on 02/23/18 08:36am

Atlee wrote:

Didn't mean to start a firestorm, but apparently I have.

A few answers or explanations.

1) I plan on getting a black flow preventer for my hose I used when dumping the black tank.

2) It sounds like some, if not most on here, believe I keep a hose hooked between the spigot at the camp site and the black tank flush system all the time. Never the case. I hook it up when I need to flush the tank.

3) It also sounds like some if not most here think I have a full black tank when hooked up. Not so. I dump the black tank, then hook up the hose to the flush system, and turn it on. I let it spray and dump at the same time, so there is no way "stuff" from the black tank can enter into the hose.

4) There is a vertical run of at least 3 feet before the black flush piping exits the rear of the trailer. The black flush connection on the rear of the trailer is nearly 4 feet above the ground.


So are you going to install the proper back check before you sell or trade your unit?

YOU may know how to avoid a SERIOUS problem but the next guy may not and that effects ALL of us.


Posted By: Atlee on 02/23/18 10:15am

No, I don't plan to replace the old piece. If the dealer supplies me with a new one under warranty, I'll put it on should I sell the trailer. But at this point I do not plan on getting rid of this trailer.


For one thing, I can't trade trailers every 2-3 years like some folks do. For another thing, this trailer suits us both quite fine. At the recent RV show, I saw no floor plan that I'd even think about trading my current trailer for.

If I should sell it before it's time, I'll instruct the buyer on what he needs to do, and since I'll be getting out of the RV lifestyle when I sell it, I'll throw in the non potable water hose with the back flow preventer.

Cummins12V98 wrote:

Atlee wrote:

Didn't mean to start a firestorm, but apparently I have.

A few answers or explanations.

1) I plan on getting a black flow preventer for my hose I used when dumping the black tank.

2) It sounds like some, if not most on here, believe I keep a hose hooked between the spigot at the camp site and the black tank flush system all the time. Never the case. I hook it up when I need to flush the tank.

3) It also sounds like some if not most here think I have a full black tank when hooked up. Not so. I dump the black tank, then hook up the hose to the flush system, and turn it on. I let it spray and dump at the same time, so there is no way "stuff" from the black tank can enter into the hose.

4) There is a vertical run of at least 3 feet before the black flush piping exits the rear of the trailer. The black flush connection on the rear of the trailer is nearly 4 feet above the ground.


So are you going to install the proper back check before you sell or trade your unit?

YOU may know how to avoid a SERIOUS problem but the next guy may not and that effects ALL of us.



Posted By: waterboy502000 on 02/23/18 10:20am

ScottG wrote:

This is probably the worst idea I have ever read about on this forum (and that's saying something).


Ditto!!!


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Posted By: Atlee on 02/23/18 10:42am

Can you and any other poster explain to me how water laced with fecal matter can flow back up the over 2.5 feet of water line, out the back of the trailer which is nearly 4 feet off the ground, back through the water hose and into the campground water system?

I understand that a vacuum on the campground water system could suck fecal laced water out of the black water tank. What I do not know is how this could happen unless the black tank sprayer is completely submerged in the fecal laced water. Is this not so?

If it is so, then why would anyone, using any common sense, hook up the water hose to the black tank flush system and open the spigot while the black tank is full? That sounds like someone who wants to over flow their toilet in the bathroom.

agesilaus wrote:

When you all come down with gastroenteritis (or worse) you'll spend more than $50 not counting your lost time. That backflow preventer is not there for cosmetic reasons.



Posted By: DutchmenSport on 02/23/18 11:14am

That's OK. When I was a kid, I sucked on garden hoses syphoning gasoline from my dad's car to use in the lawn mowers. I have no clue how many gallons of gasoline I swallowed back then.

Too much paranoia in my opinion!


Posted By: Old-Biscuit on 02/23/18 12:06pm

Atlee wrote:

Can you and any other poster explain to me how water laced with fecal matter can flow back up the over 2.5 feet of water line, out the back of the trailer which is nearly 4 feet off the ground, back through the water hose and into the campground water system?

I understand that a vacuum on the campground water system could suck fecal laced water out of the black water tank. What I do not know is how this could happen unless the black tank sprayer is completely submerged in the fecal laced water. Is this not so?

If it is so, then why would anyone, using any common sense, hook up the water hose to the black tank flush system and open the spigot while the black tank is full? That sounds like someone who wants to over flow their toilet in the bathroom.

agesilaus wrote:

When you all come down with gastroenteritis (or worse) you'll spend more than $50 not counting your lost time. That backflow preventer is not there for cosmetic reasons.



You will NOT get a 'plausible explanation' and you know it [emoticon]


Posted By: drsteve on 02/23/18 02:47pm

Atlee wrote:

...why would anyone, using any common sense, hook up the water hose to the black tank flush system and open the spigot while the black tank is full?


If common sense was actually common, many laws, rules, and safety measures would be unnecessary...


Posted By: myredracer on 02/24/18 12:16pm

waterboy502000 wrote:

ScottG wrote:

This is probably the worst idea I have ever read about on this forum (and that's saying something).
Ditto!!!
Double ditto!!!

Old-Biscuit wrote:

Waste tank would need to be FULL and PRESSURIZED to florce flow from waste tank back thru Spray Nozzle, UP 2' then down into hose which would need to be connecged to a water supply system that has NO pressure in order to 'contaminate' the water supply system
Sorry, but that is plain wrong. REALLY wrong.

First, codes and regulations cover the requirement of backflow prevention devices to prevent backshiphonage of contaminated water into potable water systems. There are several types of devices that can do that and vacuum breakers are the most reliable and safest which is why they are specified. You can find vacumm breakers on places like residential sprinkler systems for example. CGs can have them on every single faucet at a site. Ordinary check valves are not an acceptable substitute.

It is possible for there to be conditions under which there is negative pressure created in a potable water system that can draw contaminated water back into the system. The water pressure within the distribution system can fall below that of the plumbing system it is supplying when high flows are pumped out of a system like when say a fire hydrant is used. Or there could be a water main break or a water main being flushed. Or a momentary pulse in the system pressure. Or a CG shutting off it's main supply could easily cause it. There are other conditions too...

It is NOT the RVIA that decides whether or not a backflow prevention device is required in an RV. It is probably covered by NFPA 1192 which is the standard that covers RV plumbing systems. I couldn't find a free copy of it online the other day when trying to find something else so can't provide a link. Backflow prevention in CGs will be covered by a plumbing code or standard or Health Agency.

Here is Minnesota's Dept. of Health requirements for "Cross Connection Control" for example that is specifically for recreational camping areas. You can find similar requirements across the US and Canada.

If someone thinks a vacuum breaker isn't needed in your RV, you should get your RV-ing licence taken away for good and be banned from owning an RV for life. [emoticon]






Posted By: Lynnmor on 02/24/18 01:18pm

My vacuum breaker was installed next to my silverware drawer and above the electrical inlet. On the manufacturers website, it clearly states that the breaker may expel water and should be installed in a location where that water will not cause harm. Here is a spoon to stir your coffee.






Posted By: drsteve on 02/24/18 01:52pm

Lynnmor wrote:

My vacuum breaker was installed next to my silverware drawer and above the electrical inlet. On the manufacturers website, it clearly states that the breaker may expel water and should be installed in a location where that water will not cause harm. Here is a spoon to stir your coffee.


Egad. If the RV industry has a chance to mess something up, they will.


Posted By: Atlee on 02/25/18 01:52am

I'm still waiting to hear how, in the real world, and not some theoretical world in a different universe or the comedy world of the movie "RV", fecal laced water can be vacuumed back through the black tank line into the local water system, if the spray head inside the black tank is not submerged in said fecal laced water. Especially when said black water tank is 39 gallons large.

Is most everyone saying the vacuum created inside the black tank is so great it can pull water from the bottom of the tank through the air inside the tank and into the water hose, and hence to the local water system?


Posted By: Atlee on 02/25/18 01:55am

I don't want any thing, device etc anywhere inside my trailer,
whether by the silver ware tray, or inside a storage compartment that "designed" to possibly, or probably, expel water.

I'm trying like heck to keep any water outside my trailer other than inside the water lines and inside sinks, etc.

Lynnmor wrote:

My vacuum breaker was installed next to my silverware drawer and above the electrical inlet. On the manufacturers website, it clearly states that the breaker may expel water and should be installed in a location where that water will not cause harm. Here is a spoon to stir your coffee.



Posted By: JaxDad on 02/25/18 07:10am

Atlee wrote:

I'm still waiting to hear how, in the real world, and not some theoretical world in a different universe or the comedy world of the movie "RV", fecal laced water can be vacuumed back through the black tank line into the local water system, if the spray head inside the black tank is not submerged in said fecal laced water. Especially when said black water tank is 39 gallons large.

Is most everyone saying the vacuum created inside the black tank is so great it can pull water from the bottom of the tank through the air inside the tank and into the water hose, and hence to the local water system?


You would be surprised at how many people forget to turn off the water and accidentally leave the flush line running. This board alone has several such stories from people forgetting the flush or fill lines running.

Regardless, it doesn’t take much contamination for the process to start, merely vacuuming the little bit of contaminated water in the tip and then air from the enclosed space of the tank would be plenty.

Back in 2000 a small amount of E. Coli contaminated ground water made its way into a municipal well serving a small town near here. Even in the treated water of the towns water system it spread and multiplied to the point that 7 people died and 2,300 of the 5,000 people in town were very sick. If not for the Government allowing a drug in clinical trials to be given to the sick they figure at least 10 more children would have died also.


Posted By: Lynnmor on 02/25/18 07:11am

Atlee wrote:

I don't want any thing, device etc anywhere inside my trailer,
whether by the silver ware tray, or inside a storage compartment that "designed" to possibly, or probably, expel water.

I'm trying like heck to keep any water outside my trailer other than inside the water lines and inside sinks, etc.

Lynnmor wrote:

My vacuum breaker was installed next to my silverware drawer and above the electrical inlet. On the manufacturers website, it clearly states that the breaker may expel water and should be installed in a location where that water will not cause harm. Here is a spoon to stir your coffee.


For reference, see page 4:

Expelled Water


Posted By: Cummins12V98 on 02/25/18 08:23am

Atlee wrote:

I'm still waiting to hear how, in the real world, and not some theoretical world in a different universe or the comedy world of the movie "RV", fecal laced water can be vacuumed back through the black tank line into the local water system, if the spray head inside the black tank is not submerged in said fecal laced water. Especially when said black water tank is 39 gallons large.

Is most everyone saying the vacuum created inside the black tank is so great it can pull water from the bottom of the tank through the air inside the tank and into the water hose, and hence to the local water system?


So no one has EVER filled their POOP tank to the top??????

I am not much of a "what if" type of guy but this is a situation that is possible and the results would be terrible.


Posted By: Lantley on 02/25/18 08:43am

Atlee wrote:

I'm still waiting to hear how, in the real world, and not some theoretical world in a different universe or the comedy world of the movie "RV", fecal laced water can be vacuumed back through the black tank line into the local water system, if the spray head inside the black tank is not submerged in said fecal laced water. Especially when said black water tank is 39 gallons large.

Is most everyone saying the vacuum created inside the black tank is so great it can pull water from the bottom of the tank through the air inside the tank and into the water hose, and hence to the local water system?


All it takes is for someone to forget they a flushing their tanks with a Flush King or flush tank with discharge valve and you create a plausible scenario. It happens plenty of threads on this forum alone where it happens. Now consider when it does contamination could occur.


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Posted By: Cummins12V98 on 02/25/18 12:00pm

This is my way of not forgetting I am flushing my tanks! VERY easy to get distracted.

[image]


Posted By: myredracer on 02/25/18 02:20pm

We were in a large CG with a few hundred feet elevation difference from upper to lower sites. Someone at the bottom left their site and forgot to remove their city water hose. It ripped the faucet off and the CG had to shut their main supply valve off. So that set up the scenario for water being drained by gravity from all sites above the damaged faucet into the water distribution PLUS water from lower sites being siphoned back into the system. And if someone were flushing their tank and had no backflow prevention, could have contaminated the entire CG. We were leaving the CG that morning and didn't have to worry.

There are many, many real life scenarios where backflow and contamination can occur. It's not a theoretical other universe possibility. Go talk to your local public health authority and see what they say instead of being ignorant and possibly making others sick (or worse).


Posted By: Atlee on 02/25/18 02:41pm

I'm not being ignorant.

1) I'm going to get a portable back flow preventer to put on my non potable water hose when the spigot I'm using doesn't already have one. If the spigot I'm using already has a back flow preventer, then bad water can't back up anyway.

2) I don't hook up my black water tank flush until it's time to use it.

3) I dump my black tank before I used the black tank flush. I don't hook it up while the black tank is full. Nor do I use the black tank flush to fill the black tank.

5) As for water, I'm beginning to not even hook up the city water to my trailer. I will use the fresh water in the tank. When it nearly empties, I just put some more fresh water in the fresh water tank.

myredracer wrote:

We were in a large CG with a few hundred feet elevation difference from upper to lower sites. Someone at the bottom left their site and forgot to remove their city water hose. It ripped the faucet off and the CG had to shut their main supply valve off. So that set up the scenario for water being drained by gravity from all sites above the damaged faucet into the water distribution PLUS water from lower sites being siphoned back into the system. And if someone were flushing their tank and had no backflow prevention, could have contaminated the entire CG. We were leaving the CG that morning and didn't have to worry.

There are many, many real life scenarios where backflow and contamination can occur. It's not a theoretical other universe possibility. Go talk to your local public health authority and see what they say instead of being ignorant and possibly making others sick (or worse).



Posted By: Bobbo on 02/25/18 05:43pm

I just love the rationalization in any "why the rules don't apply to me" posts.


Bobbo and Lin
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Posted By: TNGW1500SE on 02/26/18 06:54am

Atlee wrote:

Didn't mean to start a firestorm, but apparently I have.

A few answers or explanations.

1) I plan on getting a black flow preventer for my hose I used when dumping the black tank.

2) It sounds like some, if not most on here, believe I keep a hose hooked between the spigot at the camp site and the black tank flush system all the time. Never the case. I hook it up when I need to flush the tank.

3) It also sounds like some if not most here think I have a full black tank when hooked up. Not so. I dump the black tank, then hook up the hose to the flush system, and turn it on. I let it spray and dump at the same time, so there is no way "stuff" from the black tank can enter into the hose.

4) There is a vertical run of at least 3 feet before the black flush piping exits the rear of the trailer. The black flush connection on the rear of the trailer is nearly 4 feet above the ground.


One thing to keep in mind is that "mods" you do, are still on the RV when you sell it. You may know how to use the RV "safely" after you do a mod, but who knows what the newbie who buys your RV will do. The valve might stop an newbie from making us all sick.


Posted By: Flapper on 02/26/18 07:07am

Atlee wrote:

Can you and any other poster explain to me how water laced with fecal matter can flow back up the over 2.5 feet of water line, out the back of the trailer which is nearly 4 feet off the ground, back through the water hose and into the campground water system?

I understand that a vacuum on the campground water system could suck fecal laced water out of the black water tank. What I do not know is how this could happen unless the black tank sprayer is completely submerged in the fecal laced water. Is this not so?

If it is so, then why would anyone, using any common sense, hook up the water hose to the black tank flush system and open the spigot while the black tank is full? That sounds like someone who wants to over flow their toilet in the bathroom.

agesilaus wrote:

When you all come down with gastroenteritis (or worse) you'll spend more than $50 not counting your lost time. That backflow preventer is not there for cosmetic reasons.


Having been in the food industry and heavily involved with Health Departments my whole life, you do not need to have the end submerged when the negative pressure happens. All you need is some droplets or "chunks" somewhere in the line to get sucked back into the main water lines. It is surprising how very little is needed to make many other people ill....


2012 F150 Eco, 4x4, SCrew, Max Tow, HD Payload
2017 Grand Design Imagine 2670MK



Posted By: mikestock on 02/27/18 07:36pm

Had a similar problem in a previously owned Montana fifth wheel. Like you, I found the price for this plastic junk to be outrageous. The thing was manufactured to fail. I bought a generic check valve and other parts to create my own, better version for a fraction of the cost. Functionally the same.


Posted By: Atlee on 02/28/18 01:06am

At this point, I have purchased a back flow preventer to put on the outside of the black tank flush. It should do all that's needed to fix the problem.

mikestock wrote:

Had a similar problem in a previously owned Montana fifth wheel. Like you, I found the price for this plastic junk to be outrageous. The thing was manufactured to fail. I bought a generic check valve and other parts to create my own, better version for a fraction of the cost. Functionally the same.



Posted By: Bobbo on 02/28/18 07:49am

Atlee wrote:

At this point, I have purchased a back flow preventer to put on the outside of the black tank flush. It should do all that's needed to fix the problem.

When I added a Tornado Tank Rinser to my previous MH, an external check valve was all they supplied with it.


Posted By: nremtp143 on 03/07/18 09:58am

I have the new brass one to take the place of mine but am now being told that the brass vacuum breaker does not have a spring loaded check valve in it and I need to put one in the line. Never heard that one before, what do you guys think about that?
This is the one I have.
[image]
[image]

This is the one like I'm being told I need.
[image]

In all I've seen, the one that I have in the top is sufficient.


2016 Montana 3790RD, Legacy Edition, G614s, TST TPMS
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Posted By: bshgto1 on 03/09/18 09:04am

Atlee wrote:

I'm not being ignorant.

1) I'm going to get a portable back flow preventer to put on my non potable water hose when the spigot I'm using doesn't already have one. If the spigot I'm using already has a back flow preventer, then bad water can't back up anyway.

2) I don't hook up my black water tank flush until it's time to use it.

3) I dump my black tank before I used the black tank flush. I don't hook it up while the black tank is full. Nor do I use the black tank flush to fill the black tank.

5) As for water, I'm beginning to not even hook up the city water to my trailer. I will use the fresh water in the tank. When it nearly empties, I just put some more fresh water in the fresh water tank.

myredracer wrote:

We were in a large CG with a few hundred feet elevation difference from upper to lower sites. Someone at the bottom left their site and forgot to remove their city water hose. It ripped the faucet off and the CG had to shut their main supply valve off. So that set up the scenario for water being drained by gravity from all sites above the damaged faucet into the water distribution PLUS water from lower sites being siphoned back into the system. And if someone were flushing their tank and had no backflow prevention, could have contaminated the entire CG. We were leaving the CG that morning and didn't have to worry.

There are many, many real life scenarios where backflow and contamination can occur. It's not a theoretical other universe possibility. Go talk to your local public health authority and see what they say instead of being ignorant and possibly making others sick (or worse).


If you have camped at Branson this is a very real scenario given the way the a lot of the campgrounds are basically cut into a hill.


2018.5 Montana 3791 Rear Den
Electric brakes suck Disk brakes it`s the only way
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2018 Ford F350 Dually 6.7 Top Dog 5595 payload


Posted By: bshgto1 on 03/09/18 09:20am

[image] border="0" alt="[image]">

So what`s wrong with this one. Seems cheap enough and you can cut it in anywhere along the line.Home Depot $15.00 Shark Bite check valve.

Posted By: drsteve on 03/09/18 05:53pm

bshgto1 wrote:

[image] border="0" alt="[image]">

So what`s wrong with this one. Seems cheap enough and you can cut it in anywhere along the line.Home Depot $15.00 Shark Bite check valve.

A backflow preventer protects your potable water. A check valve controls flow but it is not absolute. A check valve is not an appropriate substitute for a backflow preventer.


Posted By: mikestock on 03/10/18 05:10pm

I never, never, ever use my potable water hose for flushing the black water tank. I have a hose for flushing and general clean up and everything else except drinking. I have run into many dump stations that use non-potable water for rinsing and washing down the area. I, for sure, don't want that in my potable water hose.

I think the check valves are installed to prevent sewer water from backing up into the hose, for those that may be dumb enough to use the same hose for potable water and flushing. I even use this nasty hose for draining gray water into a portable tank when there is no sewer connection at the campsite.


Posted By: Lynnmor on 03/11/18 03:08am

mikestock wrote:

I never, never, ever use my potable water hose for flushing the black water tank. I have a hose for flushing and general clean up and everything else except drinking. I have run into many dump stations that use non-potable water for rinsing and washing down the area. I, for sure, don't want that in my potable water hose.

I think the check valves are installed to prevent sewer water from backing up into the hose, for those that may be dumb enough to use the same hose for potable water and flushing. I even use this nasty hose for draining gray water into a portable tank when there is no sewer connection at the campsite.


So you connect that flushing and drain hose to the campground faucet? How would I know if the faucet is clean after you leave?


Posted By: Bobbo on 03/11/18 08:20am

Lynnmor wrote:

mikestock wrote:

I never, never, ever use my potable water hose for flushing the black water tank. I have a hose for flushing and general clean up and everything else except drinking. I have run into many dump stations that use non-potable water for rinsing and washing down the area. I, for sure, don't want that in my potable water hose.

I think the check valves are installed to prevent sewer water from backing up into the hose, for those that may be dumb enough to use the same hose for potable water and flushing. I even use this nasty hose for draining gray water into a portable tank when there is no sewer connection at the campsite.


So you connect that flushing and drain hose to the campground faucet? How would I know if the faucet is clean after you leave?

My thought precisely. At some point, the whole contraption has to connect to a potable water source. I have a 3 foot length of hose with a back flow check valve on each end. I hook that 3 foot length of hose to my black tank flush (which has its own back flow check valve) then hook my potable water hose to it. That is 3 back flow check valves in series. I feel safe using my potable hose.


Posted By: RV daytrader on 03/11/18 09:10am

Doesn't every city water connection have a check valve in it??....if so the OP MAY contaminate the water already in the RV but not the campground?


YODA...our lil Toyota!
1989 Toyota Seabreeze



Posted By: Lynnmor on 03/11/18 10:09am

RV daytrader wrote:

Doesn't every city water connection have a check valve in it??....if so the OP MAY contaminate the water already in the RV but not the campground?


You and I are from PA. The faucets with check valves that I have seen in PA, I could count on one hand. Just make sure that you have a working check valve in/on your rig.


Posted By: Cummins12V98 on 03/11/18 10:24am

RV daytrader wrote:

Doesn't every city water connection have a check valve in it??....if so the OP MAY contaminate the water already in the RV but not the campground?


NO!


Posted By: Cummins12V98 on 03/11/18 10:33am

Both of my tanks have a flush system with proper anti siphon devices. I use one hose to connect my RV to domestic water supply. NOT my original idea but this system below works VERY well for filling fresh tank, everyday water usage, flushing black and and flushing grey tank. Parts from AMAZON.

[image]
[image]
[image]


Posted By: mikestock on 03/11/18 08:56pm

That's why there is a rubber bushing. It keeps your cooties isolated from mine and the last thing I do is run clean water through the hose. We're not talking about black water. Good grief. Some people have to look hard to find something to worry about.


Posted By: bshgto1 on 03/13/18 01:12pm

Isn't there a real experienced master plumber on this forum board that could give a definitive answer to this problem of what to replace the leak prone valve with, instead of opinions and Mr. fix it ideas. I thought my Shark bite check valve idea was the simple answer but called Shark bite and their engineer said it will work UNLESS the part fails and you have clean water pressure on one side and dirty water pressure on the other side the dirty water COULD back up into the clean side and contaminate the water supply, like with a garden hose situation when yo release the handle on the sprayer you still have pressure on both sides of the valve. Hence the vacuum break part. But you will never have pressure greater than the faucet on the tank flush system side because it`s always open and unable to build pressure on the back side of the valve. So I think my cheap Shark Bite idea is good but maybe not the code way to covering ALL possible scenarios. I guess you could have clogged tank sprayer at some point and have pressure on both sides of the check valve and if it failed at that very moment everybody goes blind or dies.


Posted By: mikestock on 03/14/18 09:26am

You shouldn't be talking about pressure on the tank side. If yours is set up like the one I dealt with in my previous fiver, the valve was actually high up behind an interior wall, so that when you turn off the fresh water pressure the water on either side of the check valve will naturally drain to the tank on one side and the incoming water would drain back down the pressure side. There is no reason there should be back pressure from the black water tank to the check valve.

Mine had a sign that said to always open the dump valve while flushing so I can say there should be no way to have back pressure. Having a check valve at all is being ultra conservative. The water on both sides of the check should be clean at the point when the hose is turned off or disconnected.


Posted By: bshgto1 on 03/15/18 12:41pm

Nope , no reply from a Master plumber. Still that thing that`s prone to leak is not going to stay in my camper. I did see another post of one that caused a flood on another forum board a while back. I`ll just use one of vac breaks from Lowes on the convenience center outlet with my shark bite on the down side of the system and call it a day. Like the other fella I fill my water tank through the water softener and disconnect anyway, refill as needed.


Posted By: Paul Clancy on 03/24/18 11:47am

The device on the bt flusher is a poor design. Usually cheapest of plastic that holds water and if/when the bt flush line is missed on a winterize it will crack and leak. Often behind a wall. Removing it and putting in an elbow and using external backflow valve is far better. BTDT


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