Gray Water to Black Water Tank pump

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tennsmith

tennsmith

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Joined
May 29, 2009
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Huntsville, AL
I have read, and I thought it was on this forum, an article about installing a transfer pump between the gray water tank and the black water tank.  Anyone recall the location of such a writeup?  My gray water tank is always the first to reach "full" and content transfer to the black tank would be of benefit to me.
 
You might be able to do this via gravity. I have done this on several times on an emergency basis. Frequently on an RV, they are right next to each other with a common drain valve and you can open both tanks and leave the external drain cap on and they will equalize. There are other things you can do like do dishes in a plastic tub in the sink and dump it in the toilet. Put some tubs around in the shower and dump them in the toilet, take navy showers. On our coach, we have a black tank and a yellow tank. It is yellow, because what makes it a black tank is always done at somebody else's toilet.
 
  Bob: I commented recently on installing a pump and using the grey water to flush the toilet. I read that on this forum. I wonder what would happen if you opened the grey valve then opened the black valve with the sewer cap on............would the grey run into the black until both were balanced (assuming both were same level) and leave some residual grey in the line?    terry

Edited: Thanks Lindsay Richards, you answered my question as I was typing
 
Lindsay Richards said:
...Frequently on an RV, they are right next to each other with a common drain valve and you can open both tanks and leave the external drain cap on and they will equalize...
Click to expand...

Must be an interesting process to open the cap when it's time to dump! Yuk!
 
My gray/black water tanks do share a common manifold and outlet, but I'm thinking about Joezeppy's comment (Yech!) and agree, I wouldn't want to be the one removing the cover cap! There would be a deftness of hand required to close the black tank blade valve before equalization occurred to prevent a potential backflow.

Here is one article I found:  http://www.ccis.com/home/mnemeth/grwater.htm    It is not the one I remember because that one had a macerator pump and did not require a strainer, but I'll continue searching on Google.
 
If anyone tired that proposed procedure I would hope that the black tank would be empty before attempting it.

  Not good to have a lot of sewage feeding into the grey tank. Yechh....

Best to drain the grey tank into a bucket, carry it to to the nearest toilet or road sewer and dump it there. Maybe even feed a tree in the bushes. Grey water rarely has toxic components in it.

What say...

carson FL

 
We do the dish's in a dish pan and m/t it in the toilet. Plug the shower drain and shower quick, then use a small pump driven by a drill and pump the shower water to the toilet. Pump can be purchased at ACE hardware.
 
I am putting in a compost toilet and want to expand my grey water to black water tank. Has anyone done this?
 
Welcome.... But please note this thread is 8 years old, perhaps you may fare better by starting your own and give some detail about the rig you wish to modify! A search for "composting toilet" will likely reveal several discussions on the subject.
 
The methods vary with the type of existing construction and how ambitious you are.  You can let gray expand to an otherwise empty black tank simply by placing a valve on the outlet (external hose connect) and opening both gray & black valves. Water from the gray tank will flow into the black and equalize at the same level.  Or you can add a cross-pipe from the side or bottom of the gray to the black so that it flows in directly. In general, there should be no need to pump the waste water - gravity should handle it nicely.

This add-on valve requires no mods - just twist & lock onto the outlet pipe using its standard 3" bayonet connection.

https://www.etrailer.com/RV-Sewer/Valterra/T58.html
 
carson said:
Best to drain the grey tank into a bucket, carry it to to the nearest toilet or road sewer and dump it there. Maybe even feed a tree in the bushes. Grey water rarely has toxic components in it.
Click to expand...

If my grey tank filled too fast, this is what I would do.  A five gallon pail can be taken away easily.  I just transferred ~40 gallons that way.  Or just let it drip slowly if you have good drainage.

At a park with a sewer drain, the valve can be left open so it is never an issue.

You do not want to fill up a black tank, with grey water and dump it with the bucket method, although there are worse things I have done in my life.
 
tennsmith is talking about utilizing a black tank that is no longer in active use for black water (he will have a composting  toilet).  After couple of good rinses it ought to make it reasonable as a second gray tank.
 
I installed a gray water to black tank pump on my 95 Bounder. Used a Little Giant seal less pump. Cut a "T" into the 1?" gray tank drain line to feed the pump. Reduced the "T" to accept a fitting for the ?" tubing.  Drilled an tapped a fitting about 1' above the black tank in the side of the vent stack for the ?" tubing. In our case, when the gray tank gets full we run the pump for 10 minutes. That gives us the balance we need to store the 100 gallons of fresh water we carry.

 
I have the twist-on valve that Gary linked to, and it serves us well for both equalizing the grey tank into the black tank and letting the grey tank back feed into the just emptied black tank as a rinse. We are not concerned about black tank contents possibly cross contaminating the grey tank. Every residence we've ever owned except RV's have only had one common drain system that emptied everything into a single tank.
 
NY_Dutch said:
I have the twist-on valve that Gary linked to, and it serves us well for both equalizing the grey tank into the black tank and letting the grey tank back feed into the just emptied black tank as a rinse. We are not concerned about black tank contents possibly cross contaminating the grey tank. Every residence we've ever owned except RV's have only had one common drain system that emptied everything into a single tank.
Click to expand...

This spin on valve is also a great backup valve in case one of your tank valves leaks a little. I just had that issue.
 
Rene T said:
This spin on valve is also a great backup valve in case one of your tank valves leaks a little. I just had that issue.
Click to expand...

Absolutely! I haven't had the problem on this coach, but I did on the last one. The third valve saved the day...
 
NY_Dutch said:
I have the twist-on valve that Gary linked to, and it serves us well for both equalizing the grey tank into the black tank and letting the grey tank back feed into the just emptied black tank as a rinse. We are not concerned about black tank contents possibly cross contaminating the grey tank. Every residence we've ever owned except RV's have only had one common drain system that emptied everything into a single tank.
Click to expand...

X2. We have one too. Solves the problem. Works great.
 
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