Black Tank Flush

Peto

Senior Member
Joined
Feb 12, 2024
Posts
444
Location
Scottsdale
Hello, I've never used the Black Water Flush on my Hideout because the dump stations have always been crowded and I don't want to hold up the line learning how.

I installed a dump lime at home so before the next trip I'm going to flush it.

Questions-

How often do you flush the tank?

When flushing it is it as easy as hooking the hose to the line, opening the dump valve and turning on the water until the contents run cleaner?


I know, dumb stuff but the last thing I want is any unexpected results on a new to me process involving the black tank. I'm willing to experiment to figure things out but prefer to get it right the first time in that area :)
 
First I try and use a water meter. Something like this, when I have two methods. The first is the one at the campground when I'm there for a while and I open up the valve and let it flow and turn on the flush water. When the tank is basically empty I then close dump hose valve and let the flush water put in about 20 gal of water and then dump again. Close the dump valve, turn off the flush water and open the gray water (shared outlet) and then close the gray the gray flush as I rather that in the sewer hose.



The second method is used when going home and I basically do the above process 2x and a 3rd if necessary until the water is clear of all solids.
 
To use your black tank flush, you do exactly as you stated in your first post here. Hook up the garden hose, turn on the shore water spigot, open the discharge sewer drain on the camper, let it run till it runs clean. It's just that simple.

Now, here's a little trick you can do to help keep your tanks cleaner, flushed out better and won't use any more water, it's simple back flushing.

How to do it? Attach a Flush King valve on your black and grey (combined) tanks discharge port. With the flush king in place (and sewer hoses hooked up accordingly), dump all the contents of your black tank. You can see what's happening because the Flush King has a clear section you can see through.

Once the "flow" stops, close the Flush King valve and now open your grey water valve, leaving the black tank open also. The nature of gravity will cause the grey water to back-flush into the black tank but not down your sewer hose. Don't worry, no black tank substance will flow into the grey tank because it's fuller and the shear weight of the water will force itself into the black tank. Once it equalizes, it won't flow into the grey tank either.

Now that you've back filled the grey water into the black tank, close off the grey water tank valve. This will prevent any more grey water form escaping, and it will keep any black water from somehow flushing into the grey tank.

With the grey tank valve closed, now open the Flush King (and the black tank valve is still open). What you are doing now is emptying your black tank the second time with water that was added from the grey tank.

You can do this process about 3 times with a full tank of grey water. After the 3rd time..... NOW close off the black tank and use the remaining grey water to flush out the sewer hoses.

If you do this EVERY time you dump your black tank, your black tank will be kept much, much, much cleaner and odor free.

As a final, if you want, now do a quick black tank flush with your black tank flusher and garden hose. You won't need to run it very long at all.

If you follow this process every time you back flush, you will have a cleaner tank. The black tank flush works ok, but even after you do the black tank flush, if you follow up with a BACK flush, you'll be shocked how much more "stuff" will come out, that you can actually see through that clear section of pipe on the Flush King.

Also, this process saves a LOT of water, and actually does not take any longer but a few moments than simply dumping your tanks one at a time. It takes only about 10 - 15 seconds to do the back fill, and then the tank has to be emptied of the water anyway.

If you do this every time you dump, even at dump stations, it will become a habit and you'll be doing it so fast, no one will know the difference, except you.

Give it a try. And be amazed at what discharges from your black tank!
 
If you've never used you tank flush, you should check the backflow valve. The factory has been known to install them backwards. Also, they can get stuck and pour water when you turn on the hose.

Mine is located in the sink cabinet. I have no idea where yours is.
 
My camper is set up on a permanent site. When we use it I flush the tanks after each use. Most times we are there a week or more at a time. I regularly dump the tanks about every 3 days. The day we leave I dump them and also flush them. Going to start once a year have a company come out and clean the tanks.
 
This is a different take on things and most likely not a very popular one, but it works well for me.

I don't use the the black tank flush at all, to me its almost gimmicky, years ago rv's didn't have black tank flushes and I never had a problem with a unit that wasn't equipped with one.

Bought my first rv with a black tank flush in 2010, used the black tank flush for awhile but never really saw much benefit from using it, so I quit.

That being said I do use a good amount of water when flushing a #2 and I don't drain the tank until its a least 3/4 full when parked. If we are travelling I dump when we are leaving the campground.
This has served me well for many years.
 
What do you use for a water meter?

First I try and use a water meter. Something like this, when I have two methods. The first is the one at the campground when I'm there for a while and I open up the valve and let it flow and turn on the flush water. When the tank is basically empty I then close dump hose valve and let the flush water put in about 20 gal of water and then dump again. Close the dump valve, turn off the flush water and open the gray water (shared outlet) and then close the gray the gray flush as I rather that in the sewer hose.



The second method is used when going home and I basically do the above process 2x and a 3rd if necessary until the water is clear of all solids.
 
No flush needed!

If you use a microbiological tank treatment like “Unique brand Digest It”, you don’t need to flush your black tank. In fact, the directions say a tank flush is NOT recommended because you flush the microbes out, which you do not want to do. You just pull the valve and let it drain. Close the valve, Empty your grey tank to clean your sewer hose. Add more tank treatment, add 3-5 gallons fresh water and you are done. If you are going to store your rv more than 3 weeks, flush your black tank. Then add the tank treatment, 3-5 gallons of fresh water and park your rv. While your rv is parked, the microbes will continue to clean your tank of any remaining residue, including up the sides of the tank. I have used this treatment for 5 years with no problems whatsoever. Allow at least 1 hour from last use to let the microbes break down any solids before emptying the tank. You can get the Unique digest it from Amazon, and Walmart. You can google it for other retailers. Easy Peasy!.
This tank treatment also cleans your tank sensors, not that the sensors are very accurate to begin with.
 
Last edited:
To use your black tank flush, you do exactly as you stated in your first post here. Hook up the garden hose, turn on the shore water spigot, open the discharge sewer drain on the camper, let it run till it runs clean. It's just that simple.

Now, here's a little trick you can do to help keep your tanks cleaner, flushed out better and won't use any more water, it's simple back flushing.

How to do it? Attach a Flush King valve on your black and grey (combined) tanks discharge port. With the flush king in place (and sewer hoses hooked up accordingly), dump all the contents of your black tank. You can see what's happening because the Flush King has a clear section you can see through.

Once the "flow" stops, close the Flush King valve and now open your grey water valve, leaving the black tank open also. The nature of gravity will cause the grey water to back-flush into the black tank but not down your sewer hose. Don't worry, no black tank substance will flow into the grey tank because it's fuller and the shear weight of the water will force itself into the black tank. Once it equalizes, it won't flow into the grey tank either.

Now that you've back filled the grey water into the black tank, close off the grey water tank valve. This will prevent any more grey water form escaping, and it will keep any black water from somehow flushing into the grey tank.

With the grey tank valve closed, now open the Flush King (and the black tank valve is still open). What you are doing now is emptying your black tank the second time with water that was added from the grey tank.

You can do this process about 3 times with a full tank of grey water. After the 3rd time..... NOW close off the black tank and use the remaining grey water to flush out the sewer hoses.

If you do this EVERY time you dump your black tank, your black tank will be kept much, much, much cleaner and odor free.

As a final, if you want, now do a quick black tank flush with your black tank flusher and garden hose. You won't need to run it very long at all.

If you follow this process every time you back flush, you will have a cleaner tank. The black tank flush works ok, but even after you do the black tank flush, if you follow up with a BACK flush, you'll be shocked how much more "stuff" will come out, that you can actually see through that clear section of pipe on the Flush King.

Also, this process saves a LOT of water, and actually does not take any longer but a few moments than simply dumping your tanks one at a time. It takes only about 10 - 15 seconds to do the back fill, and then the tank has to be emptied of the water anyway.

If you do this every time you dump, even at dump stations, it will become a habit and you'll be doing it so fast, no one will know the difference, except you.

Give it a try. And be amazed at what discharges from your black tank!

I'm set up permanent off grid. I do this method every weekend. I have to haul water in so I need to make the most of it.
 

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