Black Tank Flush

[Chief Brown]

When I flush my black tank in my 2021 Montana H/C I will dump tank first.
Then I close the valve and flush for 2 minutes, then I dump that. Then I close it off again and flush for 3 minutes and then dump again. I will repeat again for 4 minutes. Am I wasting water because my black tank sensors still do not work? The sensor shows full all the time.

[joe direnzi]

Welcome to montana world.I have a 3721rl 2018 and the sensors have read full since day one.

[JDDilly]

I am not sure about closing the valve, I never have. I would be afraid of over filling the tank, especially running the flush for 4 minutes. I leave the valve open and run for 3 to 5 minutes. A few times a year, I will fill the tank about 3/4 full when traveling.

After you use the tank, the sensors will not work. Most people never worry about them and dumps the tank when it does a burp like function when you flush (hard to explain, but you will notice it when it happens).

[Chief Brown]

Originally Posted by JDDilly

I am not sure about closing the valve, I never have. I would be afraid of over filling the tank, especially running the flush for 4 minutes. I leave the valve open and run for 3 to 5 minutes. A few times a year, I will fill the tank about 3/4 full when traveling.

After you use the tank, the sensors will not work. Most people never worry about them and dumps the tank when it does a burp like function when you flush (hard to explain, but you will notice it when it happens).

I stand by outside with a timer on my iphone so I do not get distracted and walk off with black tank flush running. Did that one time, not cool!!!!!

[RicknTee]

Hi Chief,
I do the same with mine, except I usually run for 5 minutes each time. I have a clear elbow coming off my black tank so I flush until it's clean. Sometimes this takes twice and sometimes more.

Thanks for your Service!

Rick

[gregdan24]

My 2010 Montana Moutaineer sensors still work. Sometimes the black tank ones get gunked up, but here's what I do.

Open the black tank drain and turn on the flush. Also, go inside and fill the commode a couple times to the top and flush from there.

When it starts running clear, I'll close the Valterra valve on my outlet and backflush with grey tank or galley tank water. Then close the black tank drain. The flush is still running. I don't get distracted...I monitor the sound of the flush in the tank and watch the sensors. When the top sensor light comes on or the flush sound stops, I open the black tank drain again. Sometimes, if at a campsite I will fill the black tank again and drain it. I feel a bit bad about wasting that much water, but I only do it on the last day before returning home.

After I do this the sensors almost always work especially the one that says "Full".

I don't add anything to my tank except the orange powder to keep it from getting smelly when in use. When running down the road between camps I like to have about 5 gallons or so of water sloshing around to clean things up.

[RicknTee]

Valterra Twist-On Waste Valve, Mess-Free Waste Valve for RV's, Campers, Trailers https://www.amazon.com/dp/B000BGHYJS...ing=UTF8&psc=1

I use this, I don't think you would ever get the last drop.

[TennTom]

I have lived on my HC 381TH going on four years now and I have ZERO issues with my indicators. I use Unique RV Digest-It. I have recommended it to others that complained about the lights not working and now continue to use it because the indicator lights are now working again.

[Chief Brown]

Originally Posted by JDDilly

I am not sure about closing the valve, I never have. I would be afraid of over filling the tank, especially running the flush for 4 minutes. I leave the valve open and run for 3 to 5 minutes. A few times a year, I will fill the tank about 3/4 full when traveling.

After you use the tank, the sensors will not work. Most people never worry about them and dumps the tank when it does a burp like function when you flush (hard to explain, but you will notice it when it happens).

Have you ever tried putting a cup of Blue Dawn dish washing liquid in it when traveling to clean it?

[Fuzzfam]

Originally Posted by Chief Brown

Have you ever tried putting a cup of Blue Dawn dish washing liquid in it when traveling to clean it?

We use Downey Fabric Softner. No suds as with Dawn. It coats the sides of the tank and lets everything slide right on out

[Dgeisser]

I like the back flushing idea. Primarily for not using so much water which is an issue in Western States. Also any concerns about dumping so much so extra soap in to what ever the end water system maybe?

[mhs4771]

I've go a step further, I use a cheap ($10-15 Buck) inline flow meter. Originally did the timer method, but realized that different places had different flow rates.
So I dump first with the Flusher running, once the flow slows down, close the valve and fill with 30-35 gals (have a 45 Gal tank), open and drain, close and fill again with 40 Gal, drain and them open Grays and while they're draining I fill and flush the toilet approx 3 times, go back outside close the Grays and refill the Black with 45 gals, drain and disconnect the flush line, close everything up and done until the next Burp.
No chems used, just a capful of Calgon and a cup of Dollar Store Pine Sol.

[DutchmenSport]

To give your sensors a better chance at working, dump your tank, flush it the best you can. Then add about 4-5 gallons of water, dump a half a cup of Dawn Dishwashing Liquid down the toilet, and drive to your next destination. The sloshing of the soap water will clean the crud hanging on the sensors and they will work again. I've been doing this for over 20 years in 4 different travel trailers and fifth wheel. Mine have always worked.

Now, to aid dumping your black tank? If your grey tank and your black tank join to a single outlet (2 valves), get yourself a Flush King valve and attach it to the drain outlet. Now do the following:

1. Drain the black tank completely and leave the valve open.
2. Close the Flush King valve.
3. Open the grey tank valve. This will now allow water from the grey tank to back-flush with force into the empty black tank.
4. Count to 10 and then close the grey tank valve.
5. Now open the Flush King again and let the black tank drain completely again.

Repeat this process 3 times, or until there is not enough water left in the grey tank to make any difference. What little bit of grey water is left after the 3rd back flush, use it to drain and clean out the sewer hose.

If you can get a clear section of drain so you can see what is actually coming out when you back flush, you'll be very surprised what, and how much more comes out.

NOW!! do a final flush with your black tank rinse and just let it run.

A few things are accomplished by doing this, namely you use MUCH less water to clean out your black tank as you are re-using your grey water instead of just dumping it and then using even more clean fresh water to flush the black tank.

Second, if you dump into a Blue Tote to cart away your waste to the dump station, you are not filling the tote multiple times as you are using only water that needs to be dumped anyway.

Third, back flushing cleans your tank, really well.

Now that you have back flushed, add the water, add the Dawn, and drive to your next destination and dump again. Sensors will work, tank is clean, never have smells or odors, and you've helped save the planet. It's a win-win in every direction to back flush.

[glb1950]

Geez I hope you're right about this, I just ordered one on Amazon and will post results here after it arrives. Thanks for the tip. I'm always trying to learn new things.

[Delaine and Lindy]

I have never payed any attention to the tank sensors. After you live in a RV you will learn when to dump tanks. I also drank black tank first, then I close valve set timer for 8 minutes set time on iPhone, and repeat, Then after flushing I put in about 3 minutes, close valve. Then empty both gray tanks. Works for me. We do know boon docking at all. I had enough camping in my 26+ years of service in the US Army. We are RVer's not campers.

Happy trails.

[Montana Man]

Originally Posted by Delaine and Lindy

I have never payed any attention to the tank sensors. After you live in a RV you will learn when to dump tanks. I also drank black tank first, then I close valve set timer for 8 minutes set time on iPhone, and repeat, Then after flushing I put in about 3 minutes, close valve. Then empty both gray tanks. Works for me. We do know boon docking at all. I had enough camping in my 26+ years of service in the US Army. We are RVer's not campers.

Happy trails.

I never drank from the black tank. There must be an easier way

[Delaine and Lindy]

Originally Posted by Montana Man

I never drank from the black tank. There must be an easier way

Good one Montana, being drafted into the US Army in 1966, I have drank from lots of sources most will never have to drank from, but no I have not drank from the black tank. Man up!

Happy trails.

[Hblick48]

[QUOTE=glb1950;1242536]Geez I hope you're right about this, I just ordered one on Amazon and will post results here after it arrives. Thanks for the tip. I'm always trying to learn new things.[/QUOTE

I used ABS cement to glue the vew valve onto the discharge end. Never have a "trickle surprise" when removing end cap.

In addition to using grey water to rinse your black tank, the new valve also allows us to extend boondocking. Shower tank always fills up before galley tank. Close the new valve at the tank discharge point. Then slowly open both grey valves. Grey tanks equalize and become one. Much more room for grey water.

When dumping, close both grey valves. Dump black tank until empty. Use procedure above to use grey water to rinse black.

[BuckandTeresa]

This is brilliant!

I use the clear section, but every time I set up camp, I get a brown trickle all over everything when I remove the black cap, no matter how careful I was to clean everything the previous trip. I will try leaving the twist-on clear section on instead, as it will rotate up above horizontal and not leak until after the drain hose is connected and rotated down.

The abs glue seems like too-permanent a solution, if the clear section ever needs replacing.
Thanks for the great tip!

[Flying Dutchman]

Hi Dutchman, I'm a dutchman too (from Rotterdam) and have lived in Minnesota since moving to the US.
We have a 3582RL. Directly after the valves the black and grey tanks join into one drain tube. We have been using your method and we can vouch for it that it works great. We use a scoop of Oxyclean instead of Dawn.