Black Tank Flush inlet

[kentdavido]

So when I connect up a hose to the black tank flush, then turned on the water, then fill the tank, then turned off the water and then finally I flush the tank. Why, when I unscrew the hose off the black tank flush inlet why does all this clean water drain out. Every time, why? Thank You.

[jtaylor1920]

There is a back flow preventer on the connection so black tank content can’t flow back into the water system. To help reduce the spray back in your wet bay disconnect the hose from the faucet first.

[kentdavido]

Originally Posted by jtaylor1920

There is a back flow preventer on the connection so black tank content can’t flow back into the water system. To help reduce the spray back in your wet bay disconnect the hose from the faucet first.

Genius, I never thought about it. Thank you so much. Makes perfect sense.

[Reverse_snowbird]

Originally Posted by kentdavido

So when I connect up a hose to the black tank flush, then turned on the water, then fill the tank, then turned off the water and then finally I flush the tank. Why, when I unscrew the hose off the black tank flush inlet why does all this clean water drain out. Every time, why? Thank You.

You are supposed to OPEN the sewer valve BEFORE you use the black tank flush. Otherwise, you run the risk of having the black tank contents come out in unexpected places.

The process....First, You should fill up the black water tank using the toilet to flush out as much as you can. Open the sewer dump and let the black water drain. Keep the sewer valve open.
Then connect the black water flush and turn on the water for a few minutes to flush the tank. Turn off the water and disconnect hose. A clear elbow will show you when the water runs clear and has drained.

Then drain the grey water and close the valve.

Hopefully, that will solve your problem.

[kentdavido]

Originally Posted by Reverse_snowbird

You are supposed to OPEN the sewer valve BEFORE you use the black tank flush. Otherwise, you run the risk of having the black tank contents come out in unexpected places.



The process....First, You should fill up the black water tank using the toilet to flush out as much as you can. Open the sewer dump and let the black water drain. Keep the sewer valve open.

Then connect the black water flush and turn on the water for a few minutes to flush the tank. Turn off the water and disconnect hose. A clear elbow will show you when the water runs clear and has drained.



Then drain the grey water and close the valve.



Hopefully, that will solve your problem.

Good morning that’s pretty much exactly what we do. I don’t fill the tank totally when I’m using the flush. I do it a couple times till I see the water come clear through our clear elbow. I was more curious why the Clearwater would come out. But I think I’ve got that figured out. Thank you so much

[Reverse_snowbird]

Originally Posted by kentdavido

Good morning that’s pretty much exactly what we do. I don’t fill the tank totally when I’m using the flush.

Yup. jtaylor1920 had the best explanation. I do that but didn't think of it.

I was most concerned when you said that you fill the tank. They advise against that.

[JohnD10]

I run the tank flush while the black tank is draining...

Helps the sludge run out by creating a flow.

I also use the gray tank water to back flush into the black tank to help remove blockage and sludge.

[kentdavido]

Originally Posted by JohnD10

I run the tank flush while the black tank is draining...

Helps the sludge run out by creating a flow.

I also use the gray tank water to back flush into the black tank to help remove blockage and sludge.

Good morning I was curious how do you drain your gray tank into your black tank. I flush the gray tank through the waste line after I flush the black to clean out those lines . But I didn’t know you could somehow flush your gray tank into the black tank.

[Egalt]

You don't drain the grey into the black. You drain the black first through the hose, and the the Grey tank through the hose to flush the hose.

[kentdavido]

Originally Posted by Egalt

You don't drain the grey into the black. You drain the black first through the hose, and the the Grey tank through the hose to flush the hose.

Exactly, I had never heard of draining the gray back into the black. That was new to me.

[ddphillips52]

This is how the gray water flush works. it takes a third valve at the outlet of the sewer pipe.

1. Drain black tank
2. Close black tank valve
3. Close sewer outlet valve
4. Open gray tank valve. Water will not go to sewer because the third valve is closed
5. Open black tank valve and allow gray water to back fill the black tank
6. Close gray tank valve
7. Open sewer outlet valve
8. Repeat as necessary

This saves many gallons of fresh water and works as well as using the black tank flush and a hose. We're full timers and I've been using this method for years. About once every 3 months, I'll actually use the black tank flush but the tank is already pretty clean. Hope this helps.

[DreiHunde]

Originally Posted by ddphillips52

This is how the gray water flush works. it takes a third valve at the outlet of the sewer pipe.

1. Drain black tank
2. Close black tank valve
3. Close sewer outlet valve
4. Open gray tank valve. Water will not go to sewer because the third valve is closed
5. Open black tank valve and allow gray water to back fill the black tank
6. Close gray tank valve
7. Open sewer outlet valve
8. Repeat as necessary

This saves many gallons of fresh water and works as well as using the black tank flush and a hose. We're full timers and I've been using this method for years. About once every 3 months, I'll actually use the black tank flush but the tank is already pretty clean. Hope this helps.

Yep! Works great

[jeff64]

Originally Posted by kentdavido

Exactly, I had never heard of draining the gray back into the black. That was new to me.

I can see where that would work to some extent. If you were using a flush king, emptied the black first, closed the flush king and opened the gray, the gray water would flow back into the black until the levels were equal. It would be interesting to see the effect if there is any

[Cypressloser]

Originally Posted by jeff64

I can see where that would work to some extent. If you were using a flush king, emptied the black first, closed the flush king and opened the gray, the gray water would flow back into the black until the levels were equal. It would be interesting to see the effect if there is any

Yes, it does work. Our black tank is mounted behind the bathroom gray tank while the kitchen gray tank is mounted about a foot higher in the upper part of the frame. I installed a blade valve near the hose hook up since we have a Wastemaster, a twist on valve on the end of the drain pipe works for most other setups. Drain the black tank first, next close the twist on valve then drain the gray tank(s) into the black tank, this relatively high flow of soapy, warm water creates enough commotion in the black tank to loosen particles from the bottom and sides that will get flushed out when you drain the black tank again, just close the gray tank first. I do this quite often when all tanks are full at the same time and find this method works as good or better than triple flushing the black tank with fresh water. Hey, and you'll never have to worry about stuff raining down from the roof

[JohnD10]

If you don't have one of these on your tank drain valves...you should (see photo below).

https://www.campingworld.com/twist-on-valve

All it takes is one brown shoe shower from a leaky dump valve and you will never own another RV without one!

Anyway, as explained above by others, once you drain the black tank (I run the built-in flush at the same time), I then close this twist-on valve and then pull the gray open and put my hand on the black pipe just before the drain valve and I can feel the water bubbling back into the black tank.

Once the bubbling stops, I then close the gray valve, open the twist-on valve, then let the black tank drain.

I do this four or five times or until I see mostly clear water coming out, then I finish cleaning the black tank the normal way.

Then drain and clean the gray tank normally as well.

If I just use the built-in black tank flush and clean until the water is running clear...this backflush method from the gray tank always makes the water look like I never even ran the built-in flush yet!

[Iggy]

I have a Camco Dual Flush Pro for my setup.
I can also force feed my campground hose into this and get clean water into black water tank also quickly.
Haven't had to use it yet but I do have it.