How to Flush Black Water Tank

AldebaranJill · January 2017

Looking for best practices to flush the black water/grey water tank (mine is combined). One of those wands or the clear elbow fitting or ? Looking for actual experience, not theoretical

Thanks!

Verna · January 2017

Clear elbow works best for me.

AldebaranJill · January 2017

Verna said:

Clear elbow works best for me.

And I presume you need to be at a full hookup vs just a dump station since you need a threaded hose?

db_cooper · January 2017

I use one of these. I have an RV dump out connected to our home septic, so I just flush it after several trips, or if we don't dump before we come home. Not cheap, but it does appear to work, I can see the jet of water blasting the tank when I look through the toilet hole.

https://www.amazon.com/Valterra-SS01-Boxed-SewerSolution-System/dp/B00CCYWJQK/ref=sr_1_1?ie=UTF8&qid=1485015995&sr=8-1&keywords=sewer+solution

Verna · January 2017

@AldebaranJill, pick up a Water Bandit (search on Amazon). It screws onto the clear elbow and will accept a bare end of a hose.

Dalehelman · January 2017

Drain black first then gray. Close valves use a bucket or some container to add 2-3 gals of water to black tank through toilet. Then open valve again. Repeat if you desire. I sometimes add some detergent to the water as well.

Nomad · January 2017

Dale - I do as you but let that soapy mix travel and slosh around.

Dalehelman · January 2017

PXLated said:

Dale - I do as you but let that soapy mix travel and slosh around.

I do as well not just every time. Always if I know I can dump again in the next day or two.

dinzzy · January 2017

I use this devise and have been very pleased. I also have a digital tank monitor which makes this much easier to do. I have a sewer dump Connection at my home that makes this very convenient.

https://www.amazon.com/gp/aw/d/B008O9DV78/ref=mp_s_a_1_8?ie=UTF8&qid=1485209350&sr=8-8&pi=AC_SX236_SY340_QL65&keywords=rv+tank+flush&dpPl=1&dpID=41d9qzPJodL&ref=plSrch

AldebaranJill · January 2017

Thanks to everyone - bought clear elbow and washing wand and got it cleaned out at previous stop where there was dump station. And @Verna your water bandit idea - It reminded me that I had one somewhere - found it this morning!

Justin_in_Seattle · September 2017

In a previous post dinzzy mentioned the Valterra Flush King Reverse RV Flush Valve. This looks like a great product.

Question, though... When you're back-flushing your black tank, what's to keep the black tank from eventually filling up and overflowing into the RV?

Also, would it be worthwhile to reverse flush the gray water tank?

Thanks for any info, RVs are new to me and I don't know much about plumbing. :-)

ChanW · September 2017

@Justin_in_Seattle, that's a good point. That's why I don't like the 'reverse flush' idea. I normally will stand inside the Tab, holding the flush valve open on the toilet, and fill the black tank fully with a hose while being able to see how full it is through the open toilet drain. It's a bit smelly, but not too bad if I make sure to have the ceiling fan blowing in, rather than out.

It seems the only way a 'reverse flush' would work is if a second person stood in the Tab, watching through the open toilet drain.

I'm also not sure what the point is to the reverse flush method.

The gray tank flush is easier, because you can run water into the sink, while watching the shower drain for over-filling.

ChanW · September 2017

Here's an interesting analysis of some reverse flush systems:

https://m.youtube.com/watch?v=dfTd0Slt_cU

jkjenn · September 2017

ChanW said:

Here's an interesting analysis of some reverse flush systems:
https://m.youtube.com/watch?v=dfTd0Slt_cU

I saw those, but they only really do one round and they don't use any enzymes.

Justin_in_Seattle said:

In a previous post dinzzy mentioned the Valterra Flush King Reverse RV Flush Valve. This looks like a great product.

Question, though... When you're back-flushing your black tank, what's to keep the black tank from eventually filling up and overflowing into the RV?

Also, would it be worthwhile to reverse flush the gray water tank?

Thanks for any info, RVs are new to me and I don't know much about plumbing. :-)

I backflush all of the time and have never had a problem with it overflowing into the RV.

4ncar · September 2017

I have seen the video too. What is compelling is the fact that using the hose fitted devices never realy flush beyond a bend in the pipe. So far my process has been to dump black, fill via toilet with a few gallons flush again(repeat until clear) put another gallon or two with enzyme..drive home. So far, so good...ready to go on next trip.

jgram2 · September 2017

I really like the Valterra master Blaster tank wand @Verna mentioned and use it every few times we dump. Attached to the hose, held inside the tank, the force rinses sides and bottom pretty darn well and if you're not careful, holding down the flush handle with one foot and wielding the wand with your hand, you could almost work a shower in there.not saying that ever happened mind you.

dsatwork · September 2017

Two weeks ago, l was using the Rhino blaster on my single valve mod while testing my portable dump tanks and hoses. I remember seeing clear water coming out and thinking it wasn't really clean. However, I also thought that I had emptied the tank and when I checked it last weekend, I found it was 50% full, when I thought it should have been empty. So, apparently it does a better job of filling the black water tank, than I thought it was.

Marceline · September 2017

AldebaranJill said:

Looking for best practices to flush the black water/grey water tank (mine is combined). One of those wands or the clear elbow fitting or ? Looking for actual experience, not theoretical
Thanks!

Hi Jill -
I have the same set up and I use the Rhino Blaster. As far as I can tell it works fine.
https://www.etrailer.com/RV-Sewer/Camco/CAM39080.html

dinzzy · January 2018

I watch my tank Gauge to make sure I’m not over filling.

dinzzy · January 2018

I continue to flush until clear water and no pieces of TP are coming through the clear 45 degree adapter I use.

sdenhof · March 2018

I am at fool hook up and wanted to give a flush a try. Do I just hook up a hose to the black flush out valve and open the black valve and watch the water flow through the clear elbow?

dinzzy · April 2018

I do this at home where I have (2) anti-syphon values, (1) at the faucet and the other on the end of the hose. This keeps bacteria out of my home water supply.

i have a hose dedicated just for this task.

With the “Flush king” attached I first drain the tank. Then I close the value on my “Flusk king” and open the black tank value. I then turn on the water supply attached to the “Flush King”. I watch my tank Gauge. When it gets to 90% I turn off the water. I then open the value to the tank and check the contents. Repeat until the water coming out is clear.

ChrisK · April 2018

dsatwork said:

Two weeks ago, l was using the Rhino blaster on my single valve mod while testing my portable dump tanks and hoses. I remember seeing clear water coming out and thinking it wasn't really clean. However, I also thought that I had emptied the tank and when I checked it last weekend, I found it was 50% full, when I thought it should have been empty. So, apparently it does a better job of filling the black water tank, than I thought it was.

How did it work with the single valve mod? I used to use one of these but figured it was just spraying in to the closed grey tank pipe so none went to the black tank.

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