Black Tank Flush

[Camp CA]

You are doing what most folks do. I never rely on my black tank level monitor since always show 3/4 full.

Might add .........consider filling:1) black tank through the flush connection with 15 gallons of water metered by an in-line flow totalizing meter, e.g., $24 P3 P0550 Water Meter, prior to use AND 2) longer than 3 minutes to ensure sufficient water is added to adequately rinse the tank (turbine helps to confirm how much water you are adding during the rinse cycle).

[Mikelff]

Originally Posted by 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.

I rarely have to flush my black tank. I use the Unique brand microbial chemical treatment in my black tank, and occasionally in my grey tanks. The manufacturer actually tells you not to flush the tank because you are actually flushing the microbes at the same time. Just use plenty of water when you flush the toilet. Not lots and lots, but an average, good flush. Empty your black tank first, “flush” with your grey tank water, and your done. Add about 3-4 gallons fresh water back to your black tank, add more microbe treatment and you are done. Never had an issue. The microbes will clean your sensors as well. They will also break down a poo pyramid, but it will take a while, several hours, for that, but it works. Only time I do a serious flush out is when I put up my RV for winter storage. It keeps my sensors clear and working, though I don't rely on them as even when they are “working” they are not that reliable. The microbes break down toilet paper big time. I would recommend you give them a try. Available at Amazon, Walmart, several places. Do a google search. Read up on the science. NEVER have to go through all the tank flushing and flushing, and flushing. NOT necessary! Check it out.

[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

[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!

[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.

[badaxemi]

Originally Posted by 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.

I use this item when my tank is showing that there is something still in the black tank when I know there isn't.
https://www.walmart.com/ip/Valterra-...zzle/163927729

[Camp CA]

Suggest installing a Valterra 3" valve with a clear section and built-in valve with or without hose flush connection and cap on the discharge line. This avoids removing the cap and draining residual gray or blank tank waste on the ground. since the drainage lines do not allow 100% disposal.

[Camp CA]

Originally Posted by Mikelff

I rarely have to flush my black tank. I use the Unique brand microbial chemical treatment in my black tank...........

I will try it!! I have used Unique on my boats, albeit the holding tanks are easily dumped since they are vacuumed out with plenty of suction that evacuates not only the holding tank but toilets and long sanitation hoses. Even then, I fill the holding tank up twice and vacuum out to make sure the system is fully flushed.

[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.

[Nightop]

To all the other advice mentioned here. At least once a year I will purchase 2 bags of cubed ice, pour those into the black tank after dumping and getting ready to move from on place to another, the ice scrubs the tank, and melts away, then I dump when I get to my next location. So, the steps I take are, dump, flush add water and ice to black tank drive a couple of hours dump and flush.

[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

[Grampa]

I use a Wan down toilet after the back wash with valve open three or four times, shout water off drain tank inbetween , keep water to trailer off when doing the Wan

[BobStack]

I’ve used the Dawn dish soap trick also and have never had a sensor issue. I also use this tank treatment after each dump.

Unique RV Digest-It Holding Tank Treatment - Powder Toilet Treatment (30 Treatments) - 41G-1 https://www.amazon.com/dp/B0742M6GF2...ing=UTF8&psc=1

[glb1950]

Got my Valterra Flush King 45 Degree Reverse Flush Valve Attachment today. What a mouthful. Didn't have a hose other than our drinking hose and didn't want to use that. So just emptied black tank and back flushed grey tank into it about 4 times and got a lot of extra brown sludge every time until I run out of grey water. Will get a hose and next time, will power blast the black tank a couple of times. So far pretty happy with the results. Thanks for all the information in this string. Gettin me some Calgon bath beads also.

[RMcNeal]

Originally Posted by glb1950

Got my Valterra Flush King 45 Degree Reverse Flush Valve Attachment today. What a mouthful. Didn't have a hose other than our drinking hose and didn't want to use that. So just emptied black tank and back flushed grey tank into it about 4 times and got a lot of extra brown sludge every time until I run out of grey water. Will get a hose and next time, will power blast the black tank a couple of times. So far pretty happy with the results. Thanks for all the information in this string. Gettin me some Calgon bath beads also.

I got our Flush King when we had a TT since it didn't have the black tank flush. I still use it so I can back flush the grey tanks, mostly the galley tank. You'd be surprised what comes out of there, even when you're being careful what you let go down the sink. It really came in handy when I first camped in freezing weather to get the frozen block in the sewer outlet thawed from the outside. I wouldn't be without one now.

[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?

[Busybob]

The best way I have found so far in cleaning and restoring your tank sensors is your flexible sewe wand. Stick it down your toilet, of course after flushing your tank out, and let it do its thing. Check your sensors. If cleared fine. If not , try again. It should work. This only a temporary fix.

[JayBee]

We had the same issue with our 2021 385MBR. I removed the bulk head in the storage compartment to see behind the convenience panel. I traced the black tank flush line to underneath the bathroom sink. It connects to a valve there and retraces back down into the chase below the main floor. It is supposed to go to the black tank from there but ours goes all the way forward to the kitchen grey tank. I proved it when our front tank was emptied but the sensor showed 2/3's full. I ran the black tank flush and the panel changed to empty on the front grey tank. During our 1 year warranty inspection I mentioned it and they assured me it was plumbed correctly. Now I know what type of service department I'm dealing with in Tacoma and won't return.



Side note: I only dug into the chase behind the panel after researching many different threads on this site. Sometimes it's hard to find but thanks to all those that made it possible for me to find and diagnose my own rig.

[Cat320]

Originally Posted by BB_TX

.... using a clear extension at the dump pipe...

Agree. I have a 90 degree clear fitting on the discharge end of the coach. There is no guessing and/or wasting water trying to determine when the tanks are "clean."