By passed Black Tank Flush back flow preventer

[Atlee]

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.




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




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

[bshgto1]

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.

[nremtp143]

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.



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


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

[Bobbo]

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.

[Atlee]

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.

[mikestock]

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.

[Flapper]

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....

[TNGW1500SE]

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.

[Bobbo]

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

[Atlee]

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).

[myredracer]

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).

[Cummins12V98]

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

[Lantley]

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.

[Cummins12V98]

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.

[Lynnmor]

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

[JaxDad]

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.