Black Tank Flush

[lannieoakley]

2019 5th wheel 529BH
Hi all, Been reading the threads on flushing the black tank. About to do It for the first time. New 5th wheel owner. Just want to make sure I do it correctly. Are there specific steps? How does the blank tank vent air pressure while your filling it?
Thx
Leslie

[eye95]

Venting won’t be an issue if you keep the dump valve open to the sewer while flushing.

[SeaDog]

Make sure you keep the dump valve open while you flush. I recommend a lear elbow on the dump connection so that you can see when the tank is clean.

[Mr. Dan]

Most modern black tanks have a vent pipe out the top of the trailer.

[eye95]

Originally Posted by SeaDog

Make sure you keep the dump valve open while you flush. I recommend a lear elbow on the dump connection so that you can see when the tank is clean.

A “lear elbow”? I personally use a “clear elbow”.

[SeaDog]

fingers were not moving as fast as I was thinking so add "C" to lear (clear)

[Scrapper]

And, Don't ignore the sticker next to the black tank flush which says to leave the dump valve open. You may not like what happens if you do. See this recent post as to what can go wrong.
https://www.forestriverforums.com/fo...ak-209782.html

[jd4010]

For the past 2 decades my RVs had (and have) black tank flush connections. They are not as powerful as I wish they were but they do help. Here is my process:
1) If the tank isn't 2/3 to 3/4 full, I use the black flush to fill it up to that point. Logic here.....I want force and volume to push out when I open the valve
2) Once to the 2/3 or 3/4 level, I open the valve keeping the flush running
3) When I see the volume in the clear elbow slow dramatically, I will dump a 5 gallon pail of water directly into the toilet. This helps to break up the mound of crap that forms under the toilet piping.
4) I close the drain and let it fill a good 1/2 to 2/3 of the way
5) When at the 1/2 to 2/3 way, I pull the valve, let it drain and dump another 5 gallon bucket of water into the toilet.
6) Close the drain again and fill 1/2ish again and dump
7) Turn off the flush valve, close the black tank valve, dump in 5 gallons of water mixed with toilet chemicals
8) Done

Been doing this process for years and years and never an issue. Yes...you do have to pay attention to water levels....but it leaves the tank clean.

Was mentioning to the wife this weekend while cleaning the tanks that I wish all three tanks (just not the black) had flush sprayers in them. They could simply use 1 input with a three position valve. Sometimes that gray tank can be worse than the black with food particles, etc. And at that, I wish the tank sprayers had more force/power almost like a dishwasher spray pattern.

[Semperfi24]

Agree with leaving it open. I usually start the flush before the tank is empty. And then when it does empty, I will close the tank for 30 seconds and then open. Wait for it to empty, and repeat the closing an opening. You will be surprised by how much is still in the tank. I have had the "water run clear", then performed the close/open procedure and the sudden rush of water exiting the tank will still bring a lot of "stuff" out with it. Everyone has their own method. For me, it is turning it on about half way through, followed by several close/open cycles. When I am satisfied, I turn off the flush, close the tank, and remove the dump hose.

Last note, when I am doing the close/open cycles, I never walk away. If something interrupts me before my next open, I just open it and take care of whatever needed my attention, then I return for more close/open cycles.

[Semperfi24]

(duplicate message)

[eye95]

The leaving of the valve closed for the stated reasons in the above to posts may have some validity. However, if you use either of these two techniques, make danged sure that the tank does not fill completely!!!

I personally won’t ever risk it.

[lannieoakley]

Thanks everyone. Going to give it a try Friday!

Leslie

[NavyLCDR]

Originally Posted by Leslie Lindell

Thanks everyone. Going to give it a try Friday!

Leslie

Who would think that dumping the black water tank could be so exciting!

I still, though, really do enjoy everything about RV camping and for me the whole process of getting there and setup and getting home is the most fun.

[Scrapper]

Originally Posted by NavyLCDR

Who would think that dumping the black water tank could be so exciting!

I still, though, really do enjoy everything about RV camping and for me the whole process of getting there and setup and getting home is the most fun.

You know the definition of insanity is repeating the same task over and over expecting different results.

When it comes to camping this does not hold true.

[NavyLCDR]

Originally Posted by Scrapper

You know the definition of insanity is repeating the same task over and over expecting different results.

When it comes to camping this does not hold true.

Well.... I've had one set of "different results". One camping trip I had a flat tire, hail storm, pouring rain, horrible camping site, had to fill my freshwater tank 5 gals at a time from a spigot 2 camp sites away and across the road (with the spring loaded type of handle that you have to hold open), black gooey mud that stuck to EVERYTHING, and the night ended with a SWAT team banging on my trailer door at 8:10 PM.

[bikendan]

Originally Posted by NavyLCDR

Who would think that dumping the black water tank could be so exciting!

I still, though, really do enjoy everything about RV camping and for me the whole process of getting there and setup and getting home is the most fun.

I agree!

[lannieoakley]

Originally Posted by eye95

A “lear elbow”? I personally use a “clear elbow”.

One came with the trailer. Should be helpful.

[Scott and Deb]

Hi everyone, we're new to the forum so I thought Id see if anyone here has any thoughts/ideas/answers. We have a 2015 32 ft Flagstaff fifth wheel, purchased last year. We used it at the end of the season last year, attempted to use the black water flush, water started immediately pouring out from inside the area where the line is "supposed" to be linked to, I assumed, the black water tank. We looked more closely today, the line from the flush goes directly up to the bathroom and not down into a tank. Anyone ever heard of this or are we just a little ignorant. We "assumed" when we hooked the hose to the black water flush that it would flush the tank. Other trailers that we've owned with this option did just that...…..flush the tank.

[bubbles]

Yes into the bathroom probably under the vanity. Look under the vanity and you will see a vacuum breaker/check valve that routes the cleanout plumbing back down to the tank. This is the standard installation for an rv black tank cleanout. Of course the valve could be located some other place depending on the rv.