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.

[Paul_Clancy]

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

[bshgto1]

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.

[mikestock]

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.

[bshgto1]

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.

[mikestock]

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.

[Cummins12V98]

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.

[Cummins12V98]

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!

[Lynnmor]

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.

[RV_daytrader]

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?

[Bobbo]

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.

[Lynnmor]

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?

[mikestock]

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.

[drsteve]

bshgto1 wrote:
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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.

[bshgto1]

[img][/img]

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.