Black tank flush question

[mTn_biKer65]

Originally Posted by Jim in Halifax

I recently was rinsing our black water tank and a neighbor camper came over to ask a ?'n...Went off with him.....Heard the BH holler.....Water came up thru toilet on BRm floor..A mess!!!!!!!!! just stinky water as I had rinsed just a few mins previous........Would like to install a water timer on hose to shut off after a few minutes......This will not happen again!!!!!!!!!!!!!! J

Hmmm I actually have a sprinkler timer I bought but never used for the lawn. Might just need to give this one a try to see how it works.

[Carrier]

Originally Posted by richp

Hi,

I added a simple, cheap in-line valve right at the female fitting that takes the flush hose. Close that valve before shutting off the water at the faucet, and there will be no back-flow.

FWIW.

Rich Phillips

Yup that's what I do as well.

[VinceU]

Originally Posted by youroo

If your the Next person to hook up the Hydrant that has been (Backfed?) from a hose that was filled with (SEWER WATER) you would want one! Youroo!!

Youroo is correct here. The VacBreak is installed under Fed Regs by USPHS ( US Public Health Service regulations.) the purpose is not to drain the pipe or act as a check valve. It's design and only purpose is to break a vacuum if the pipe it's installed in attempts to flow backwards. This can happen if the shore supply should abruptly lose pressure, well pump failure, or city water main failure. If that occurs, the branches can and will flow backwards. Piping under "dirty water" ie sinks, tubs, holding tanks etc, can allow this stuff to be sucked into the fresh water mains. Tank flush piping normally in tank end about 1/3 way down andl could certainly fall into the storage area mentioned above. We are dealing with ecoli bacteria here, the more precautions the better to prevent accidental spreading disease. To visualize how to make vacuum, picture a 100' well stops suddenly. The water within will seek its own level, all the water in its system will fall with it thus vacuum at all its spigots and open valves.


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[VinceU]

Originally Posted by youroo

That's OK F/R makes lots of RVs and they are Plumbed different! Youroo!!

Originally Posted by youroo

If your the Next person to hook up the Hydrant that has been (Backfed?) from a hose that was filled with (SEWER WATER) you would want one! Youroo!!

Youroo is correct here. The VacBreak is installed under Fed Regs by USPHS ( US Public Health Service regulations.) the purpose is not to drain the pipe or act as a check valve. It's design and only purpose is to break a vacuum if the pipe it's installed in attempts to flow backwards. This can happen if the shore supply should abruptly lose pressure, well pump failure, or city water main failure. If that occurs, the branches can and will flow backwards. Piping under "dirty water" ie sinks, tubs, holding tanks etc, can allow this stuff to be sucked into the fresh water mains. Tank flush piping normally in tank end about 1/3 way down andl could certainly fall into the storage area mentioned above. We are dealing with ecoli bacteria here, the more precautions the better to prevent accidental spreading disease. To visualize how to make vacuum, picture a 100' well stops suddenly. The water within will seek its own level, all the water in its system will fall with it thus vacuum at all its spigots and open valves. Doesn't matter 3 or 5' loop height, perfect vacuum will pull 34'h! Vac brk must open to prevent tragedy.


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[OldCoot]

Originally Posted by VinceU

Youroo is correct here. The VacBreak is installed under Fed Regs by USPHS ( US Public Health Service regulations.) the purpose is not to drain the pipe or act as a check valve. It's design and only purpose is to break a vacuum if the pipe it's installed in attempts to flow backwards. This can happen if the shore supply should abruptly lose pressure, well pump failure, or city water main failure. If that occurs, the branches can and will flow backwards. Piping under "dirty water" ie sinks, tubs, holding tanks etc, can allow this stuff to be sucked into the fresh water mains. Tank flush piping normally in tank end about 1/3 way down andl could certainly fall into the storage area mentioned above. We are dealing with ecoli bacteria here, the more precautions the better to prevent accidental spreading disease. To visualize how to make vacuum, picture a 100' well stops suddenly. The water within will seek its own level, all the water in its system will fall with it thus vacuum at all its spigots and open valves.


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Then why have a backflow preventer behind the inlet hose like mine did?

[VinceU]

That is a check valve prevents pump pressure from escaping when hose is not connected. Few years back mine froze and I managed to dislodge the valve disc with pump on.....

[ActionJackson]

Originally Posted by dustman_stx

Not a hydraulics expert, but my thinking- and the way I've flushed the black tank in the past is-

1. Drain black tank
2. Close main valve
3. Connect water hose to black tank connection
4. Fill tank to 3/4 full
5. Drain black tank with water on
6. Repeat steps 4 and 5 ~ 3X

So you waste 75 gallons ( or there about) of fresh water flushing out your black water tank??? Wow.... No need for that.

[OldCoot]

Originally Posted by VinceU

That is a check valve prevents pump pressure from escaping when hose is not connected. Few years back mine froze and I managed to dislodge the valve disc with pump on.....

Has nothing to do with the pump, it is a separate hose connection strictly for the black tank flush.

[dustman_stx]

Originally Posted by ActionJackson

So you waste 75 gallons ( or there about) of fresh water flushing out your black water tank??? Wow.... No need for that.

You don't get to make that call for me. I don't water my lawn and don't have a pool, so we'll say I'm still much more conservative than most folks. I will say this, however; I have a dump station at my house where I flush and the camper leans heavily toward the sensor side. Therefore, in reality I'm not actually filling my tank to 3/4 full. I only fill until the sensors read full and are covered during the flush.

[Flybob]

Originally Posted by dustman_stx

Not a hydraulics expert, but my thinking- and the way I've flushed the black tank in the past is-


4. Fill tank to 3/4 full
5. Drain black tank with water on
6. Repeat steps 4 and 5 ~ 3X


?

Huge waste of water and fills dump station tank quickly. If you have a 45G black tank and use this procedure, you add 100 G extra to dump station, If 40 Rv's do this in a day that is 4000G . End result is the park has increased pumping costs and raises fees.

[onetonford]

I usually keep my valves closed at my full hook up site until tanks are almost full then dump black first and gray after. Then before leaving add some water to tank about 20 gallons each for the ride home when I get home or to the next place I'm staying at I dump Black first then gray while dumping gray I have the intank spray going and then open the black again close gray add some water and dump again cleaning remaining gunk out of hose. Has worked for me over 35 years and never had a plug or bad smelling tank etc.

[ActionJackson]

Originally Posted by dustman_stx

You don't get to make that call for me. I don't water my lawn and don't have a pool, so we'll say I'm still much more conservative than most folks. I will say this, however; I have a dump station at my house where I flush and the camper leans heavily toward the sensor side. Therefore, in reality I'm not actually filling my tank to 3/4 full. I only fill until the sensors read full and are covered during the flush.

Sorry, was not trying to make any call for you. You are welcome to do as you please. However, 2 gallons of water and 5 minutes total using a swizzle stick will accomplish the same results (if not better as it will flush the whole tank, top also).

[dustman_stx]

Originally Posted by ActionJackson

Sorry, was not trying to make any call for you. You are welcome to do as you please. However, 2 gallons of water and 5 minutes total using a swizzle stick will accomplish the same results (if not better as it will flush the whole tank, top also).

Not in my experience.

Edit: And I was hoping to convey that I was saying that(about being my call) jokingly with the smiley. No harm intended.

[dustman_stx]

Originally Posted by Flybob

Huge waste of water and fills dump station tank quickly. If you have a 45G black tank and use this procedure, you add 100 G extra to dump station, If 40 Rv's do this in a day that is 4000G . End result is the park has increased pumping costs and raises fees.

You need to reread my posts. I do my flush procedure at home. And I don't use anywhere near 100G doing it. I'd be estimating because of the lean of the camper, but I'd say I use maybe 50 gallons at most doing my procedure. I didn't make all this clear in my original post about my procedure- my fault.

[richp]

Hi,

My use of an in-line shutoff valve is not meant as a replacement for an anti-flowback mechanism.

As it happens, my anti-flowback valve must be somewhere further inside the trailer, because there always was some dribble out of the connector when I took off the feed hose. This valve prevents that from happening, as well as generally giving me more positive control over the whole process.

FWIW.

Rich Phillips

[youroo]

Originally Posted by richp

Hi,

My use of an in-line shutoff valve is not meant as a replacement for an anti-flowback mechanism.

As it happens, my anti-flowback valve must be somewhere further inside the trailer, because there always was some dribble out of the connector when I took off the feed hose. This valve prevents that from happening, as well as generally giving me more positive control over the whole process.

FWIW.

Rich Phillips

Richp,do you leave the little S/O valve attached or remove it when done? Youroo!!

[richp]

Hi Youroo,

I leave it there all the time, in the closed position when not in use.

I also had a dribbling problem from the hose going to the faucet -- wetting the floor of my compartment when I unhooked it after a flush. I got tired of mopping up afterward, so I attached (to the shutoff valve) a short piece (maybe 30"long) of hose, and I leave that attached all the time too.

What I do is I hook up the hose leading to the faucet to this shorter one, which is long enough to dangle outside the door, below the floor level of the compartment. When I unhook from the faucet, the dribble from unhooking the long hose is outside -- down to the ground. When I"m done, I just turn the short hose up, where it fits in a convenient place in the compartment.

Yeah, I know it seems like overkill or over-engineering, or over-thinking things. But it's actually simple, and it works for me.

Hope this helps.

Rich Phillips

[ependydad]

Originally Posted by richp

I leave it there all the time, in the closed position when not in use.

This is how I used to do it- a "Y" splitter for my black tank hose (with the anti-flow back thinger inside the camper). I came really close to flooding my black tank because of the cheap "Y" that I used. It let a dribble go through the hose and slowly filled my black tank the day after I dumped/flushed it.

Sadly, yes- it was a Harbor Freight splitter. And no, I didn't buy it because it was cheap; I bought it because I was there and it was there and convenient. I've since moved up to a good 4-hose manifold (is that the right word?) but still disconnect my black-tank flushes each time. With quick connects, it is easy to do- just pop and drop 'em. Though, I should probably invest in some caps to keep insects out.

[richp]

Hi ependydad,

Mine has separate inlets for fresh feed and black flush, so I'm not at risk for that king of thing.

Rich Phillips

[ependydad]

Originally Posted by richp

Hi ependydad,

Mine has separate inlets for fresh feed and black flush, so I'm not at risk for that king of thing.

Rich Phillips

On the camper/RV? Me too.