Good Black flush "trick" or bad idea?

That is actually a common 'trick' that has been used for a long time, using grey tank water to flush out black tank.

I personally don't use that approach, as would always be concerned that I'd mess up and let 'stuff' from the black tank get over into grey tank. That, and I find its more effective to just use the dual flush pro device we have to back-fill the black tank with as much fresh water as appropriate, and dump it out. Using this approach, I can fill up and flush out the black tank as many times as necessary until I see the water flowing clear and know that the black tank is clean. Then, I still have entire grey tank to dump, to clean out the hose.

Even better would be a tank rinser or 'quickie-flush' system as I believe it is called. I installed one in our last RV and really liked it. RV we have now unfortunately does not, and no good way to install one, so the dual flush pro unit has to do. Our next RV will definitely have a tank rinser, though.

TNGW1500SE wrote:
When dumping my tanks, I've got a new "trick". I drain the black water first and let the hose and tank empty out. Then I leave the black valve open, hold the sewer hose up (above the level of the tanks) and open the grey valve. This lets the grey water rush into the black tank. Before the grey water stops rushing into the black tank, I close the grey valve and lower the hose, thus emptying the black tank again. I'm able to do this "flush" 3 or more times depending on the grey tank level. I leave some grey water for the final hose rinse. I'd estimate I use 5 to 8 gallons of grey each time I do this "flush". I'm careful not to let the tanks equalize allowing black water to the grey tank. I can tell when the greys running low because the gushing (from tank to tank) slows down. It seems to really help clean the black tank. I've got one of those clear fittings so I can see the color of the water. The first time I do it, the water is nasty brown but after a couple of cycles it looks like "clean", soapy grey water. I wish I had a third valve where the hose is connected but there's no room to install one so I just hold the hose up to stop the water flowing to the sewer. Soooooo,,,,, is it a good "trick" or a bad idea?

Well Sir,
First off, "TNGW1500SE", I highly suspect that, that means, Honda Goldwing, 1500 SE version, correct? If so, that's a very nice bike. Had one. Now, as for your "trick" of flushing your black tank with your grey tank, well, it's a plan, not sure if it's a good plan but, never the less, A PLAN. You see, as you more than likely know, the water that comes out of the gray tank is pretty ugly water too. It's "cleaner" than what comes from the black tank for sure but, it's still pretty dirty, smelly stuff.

And, based on some basic gravity/physics here, it's a marginal plan at best. You see, your solids, in your black tank, may or may not, reside near the dump valve. They can travel back further into the black tank. And, based on your angle of dump, (as in a slight lean of the coach towards the dump valves, in order to evacuate as much of both tanks as possible) then transferring the gray into the black, quite possibly not flush out, all the remaining solids etc. that might have migrated to the rear section of the black tank.

Are you seeing what I'm trying to explain?

Depending on certain circumstances, i.e. no one waiting behind to dump, grounds and provisions allowing, I will in some cases, put out my ramps to drive up on, on the opposite side from the dump valves. That way, when I open each one up, due to the angle of the tanks, they dump vigorously and completely, in considerably shorter time, than they would if I was just sitting level. There are even some dump stations that are off level, the wrong way so, your tanks don't even empty all the way.

And, in my opinion, you're kind of taking a chance, holding onto that hose, up in the air, while things (ugly stuff) are flowing from one tank to the other. A hose clamp could give way, a small, tiny leak could erupt and, get on you, your cloths etc. Ever see the movie "RV" with Robin Williams? I see that scene in the movie when you talk about your plan. Not that it will happen but, to me, the potential for an issue is greatly enhanced. Your choice Partner, if it works for you, have at it.
Scott

I'm fortunate that Monaco gave me a factory supplied hose connection that I use to flush out my black tank. I just hook up a garden hose to the faucet and let it run until the water comes out clear. Listening to it while in operation it seems to flip around and wash out the entire tank.

Click
It's been done before. :)

I don't see the problem if a little black water gets into grey tank when equalizing. What would it do? It will come out at the next dumping session.

We have just one holding for black AND grey (189 gal.) We also have a built-in flush connection if I want to clean out the tank.

I, too, think it's a little risky to hold up the hose. What if you get stung by a bee?

MM.

dougrainer wrote:

darsben1 wrote:
Question is why?
I never use tricks just wait till full or almost full. Dump, throw bucket of water down toilet, close valve then GET ON WITH MY LIFE! Your Poop is not hazardous waste

Lets see, Your DENTIST must dispose of the items in your mouth and treat as hazardless waste. But your S**t is not hazardless waste?????? I would rather have someone sneeze on me than POOP on me:B This trick is kind of neat, but I would rather put that clip on 3 inch dump valve that snaps on where the hose snaps on and then have that 3 inch valve closed and then open the Gray and Black and let the gray equalize with the black and then dump both instead of holding the hose up. Obviously I would do as the poster and dump the black first. Doug

https://www.amazon.com/dp/B000BGHYJS/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687602&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000EDUTQ8&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=8T773F90NDRA6MZJJ9DS

THE BLOOD IS HAZARDOUS WASTE. Hospitals do not even red bag poop as hazardous waste.

I use a third valve and section of clear pipe to do a back flush. Works very well when using the internal flusher is not an option. Usually get three back fills from the gray tank. Last one the water looks like normal gray tank water.

darsben1 wrote:

dougrainer wrote:

darsben1 wrote:
Question is why?
I never use tricks just wait till full or almost full. Dump, throw bucket of water down toilet, close valve then GET ON WITH MY LIFE! Your Poop is not hazardous waste

Lets see, Your DENTIST must dispose of the items in your mouth and treat as hazardless waste. But your S**t is not hazardless waste?????? I would rather have someone sneeze on me than POOP on me:B This trick is kind of neat, but I would rather put that clip on 3 inch dump valve that snaps on where the hose snaps on and then have that 3 inch valve closed and then open the Gray and Black and let the gray equalize with the black and then dump both instead of holding the hose up. Obviously I would do as the poster and dump the black first. Doug

https://www.amazon.com/dp/B000BGHYJS/ref=pd_lpo_sbs_dp_ss_3?pf_rd_p=1944687602&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B000EDUTQ8&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=8T773F90NDRA6MZJJ9DS

THE BLOOD IS HAZARDOUS WASTE. Hospitals do not even red bag poop as hazardous waste.

The RV factories will not allow us to ship back Holding Tank flush nozzles or Dump valves as they are classified as Hazardous Waste. May not be the EPA definition, but that is what we go by. Doug

rgatijnet1 wrote:
I'm fortunate that Monaco gave me a factory supplied hose connection that I use to flush out my black tank. I just hook up a garden hose to the faucet and let it run until the water comes out clear. Listening to it while in operation it seems to flip around and wash out the entire tank.

It will overflow into your gray tank if the valves are closed for too long, and then out your shower drain...don't ask how I know this to be true.

If it works for you O.K.! Not my cup of tea. I drain black then gray then turn on the oscillator to clean everything. Then I shut all valves and put 1/2 cup Blue Dawn in black tank followed with 5 gallons and let it slosh around until I get to next destination, then drain.