Need to use pressure regulator on black water flush hose?

[JoeInPA]

2021 Salem FSX 178BHSK. Do I need to use a pressure regulator at the black water supply spigot (pump handle-type water supply, so I am sure it is fairly high pressure) at a truck stop dump station before connecting my black water flush garden hose to the water spigot and then connecting to my camper's black water flush port, like I have to do with the fresh drinking water hose at the spigot end of that hose? Does that black water flush port on the trailer go direct into the tank, or through the same small types of pipes as the rest of the trailer's plumbing system?

[dat]

I would say that it does have to go through a regulator, looks like the same hose and clamps as the rest of the plumbing, as cheap as a regulator is, it isn’t worth taking a chance on having to do repairs on lines or clean up water from a blown off line.
Now saying that, it isn’t a closed system holding pressure from the hose and not releasing it on the other end, so it “shouldn’t” build up enough pressure to hurt anything, but I wouldn’t take a chance without one.
Just my opinion though

[ependydad]

It goes through pex pipes into a 1-way check valve/back flow preventer in the bathroom and then into the tank.

People are split as to if a pressure regulator is needed or not on the black tank flush.

[MR.M]

Originally Posted by JoeInPA

2021 Salem FSX 178BHSK. Do I need to use a pressure regulator at the black water supply spigot (pump handle-type water supply, so I am sure it is fairly high pressure) at a truck stop dump station before connecting my black water flush garden hose to the water spigot and then connecting to my camper's black water flush port, like I have to do with the fresh drinking water hose at the spigot end of that hose? Does that black water flush port on the trailer go direct into the tank, or through the same small types of pipes as the rest of the trailer's plumbing system?

Never used a regulator on black tank flush. open system and i want the pressure to wash out the tank . 7 yrs no problems

[5picker]

No need for a regulator on a black tank flush.

It is an open ended system with it's own plumbing (and no way to close it off where pressure would build up in between the outside connection and the flush nozzle) so no need for the regulator. More pressure/flow is better.

[DrLewie]

The instruction manual with my first RV with a flusher said "do not use a pressure regulator" to flush the black water tank. Apparently the hose connector is attached to the flusher arm with a stronger connection than the interior plumbing. I've also been told that the interior piping on modern RVs aren't as susceptible to water pressure than older systems. I don't use a regulator on the flusher but I use one for the city water connection. BTW, there is always the possibility of contamination of the fresh water hose caused by back flow when used on a flusher, which is why many campgrounds have a check valve on the fresh water spigots.

[Tundra 2014]

Use a separate hose from sinking water. They sell orange hoses for this. Leave the tank valve open, no need to use a pressure regulator. I have never heard of anyone breaking one. If do use an anti-back flow valve on mine which does reduce pressure slightly. Most campsites we visit usually have the anti-back flow valves on the faucets already.

[CGK]

The only time I didn't use a pressure regulator on the black water supply connection, the very cheap, plastic anti-siphon valve blew and sprayed (clean) water all over the inside of the TT's bathroom vanity. It was a pain to replace, since I could only use one hand to do the work; but I was able to replace it with a brass valve. Lost many rolls of toilet paper stored in the vanity, and part of a day that was supposed to be a hiking day, but got the job done. Now I'm not disagreeing with those who say it's an open system and not likely to be damaged - theoretically that is correct.....my experience may have been coincidental or it may be that the plastic anti-siphon valve installed in most RVs is flimsy enough to be damaged by a sudden blast of high pressure water. I think it's better to be safe than sorry, so I use a regulator for all the water connections.

[JoeInPA]

Thank you for all the great answers!

[GFD47]

Our county lets residents dump free at the sewage treatment plant. I usually dump elsewhere but occasionally go to the treatment plant because they have 80 psi at their cleanout hose connection and that puppy loosens stuff that even my home (well) system doesn't budge. Been doing that for seven years now with no overpressure issues.

[JoeInPA]

When flushing our black and gray tanks at a dump station the other day, I accidentally forgot to close the slide on the gray waste release side after using that to flush the remnants of the black waste out of the stinky slinky. With it still open, I started running the black water flush hose into the trailer. It was like that for about 5 mins. before I realized and closed the gray valve slide. Looking at the vee shape of the waste ports, it seems unlikely, but is there any way I cross-contaminated my gray water tank?

[NavyLCDR]

Originally Posted by JoeInPA

When flushing our black and gray tanks at a dump station the other day, I accidentally forgot to close the slide on the gray waste release side after using that to flush the remnants of the black waste out of the stinky slinky. With it still open, I started running the black water flush hose into the trailer. It was like that for about 5 mins. before I realized and closed the gray valve slide. Looking at the vee shape of the waste ports, it seems unlikely, but is there any way I cross-contaminated my gray water tank?

Water will flow to the path of least resistance, which from the black tank would be through the open waste valve into the dump station rather than back into the grey water tank, which would be both uphill and likely a 1 1/2" pipe whereas the hose to the dump station is 3".

And my answer is no to the original question - no regulator when flushing black tank.