Converting Bath Sink to drain to Black Tank versus Gray Tank

[dkoldman]

Originally Posted by dickb46

I'm glad I read this thread, I ordered that Twist On Waste Valve instantly ;-}
dickb

Originally Posted by Nalle

This is my $20 and 2 minute fix. Works great with my tank layout. When Grey Tank approaches full, close added third valve and open Grey. Then open Black and let gravity do it's thing. Then close Black and leave added valve closed until time to dump. Then close Grey and open Black and added valve. Follow with Grey.


https://www.winnieowners.com/forums/...1&d=1696261054

I like the concept of the twist off as well, as it may give me another option. See post #8 and my comment. I still have some research to do. Not sure when I will get around to it, but would love to learn your knowledge of a few things off the top of mind head to understand.

1. In my manual, it says NOT to have the Gary & Black tanks opened at the same time? I do have them opened at the same time on occasion, but it is after the black tank has been fully dumped. I let the gray overflow into empty black, close gray, and then drain black. I do several times until all of my gray is gone.

2. What are your black & gray tank capacities? Mine is 40gals & 61 gallons respectively. Do you know how many gallons are in you black tank if you allow max gray tank capacity opened to flow to black? i.e. in my case 61 gals that flows from my gray makes how many gallons in black? I think the answer may vary by coach with placement height and physical dimensions being critical factors. I intend to test this with 61 gallons of clean water in my gray tank

3. Assuming that all of the above is permissible and beneficial, in my case; I already have a Flo Jet Macerator. I twist it ON/OFF for each use. I could simply use it as I do in #1 above, I could just leave it on temporarily until I wish to pump it out.

I bet Morich will give me a hard time for not pulling my plumbing diagram to see the tanks positions, and get the tanks dimensions. But I think I will wait until both tanks are empty. Fill the gray with fresh water, and then open black tanks and see if I hit 1/3 or 2/3 on black tank?

The math is relevant because today I will hit 2/3rds on gray which means at least 40 gallons and the black at the same time may read 1/3rd tank (at least 13 gal); if the tanks were equal height and size 61 gallons from Gray may be 30 gal in Gray and 30 gal in black, but since we know the black is smaller it may be 36 gal or higher in black which is to close to Full for me. I don't want to go to the other extreme or risk contamination on my Gray thus my due diligence.

[Wyatt]

Originally Posted by Nalle

This is my $20 and 2 minute fix. Works great with my tank layout. When Grey Tank approaches full, close added third valve and open Grey. Then open Black and let gravity do it's thing. Then close Black and leave added valve closed until time to dump. Then close Grey and open Black and added valve. Follow with Grey.


https://www.winnieowners.com/forums/...1&d=1696261054

So I’m assuming you do this only when a hose is connected to the drain, right? Otherwise you’d have a mess on your hands—literally, once you take that cap offf…

My unit advises against that due to cross contamination…

[dkoldman]

Originally Posted by Wyatt

So I’m assuming you do this only when a hose is connected to the drain, right? Otherwise you’d have a mess on your hands—literally, once you take that cap offf…

My unit advises against that due to cross contamination…

My manual says the same thing, heaven forbid a backup through the gray plumbing, the black is bad enough.

If you look at Nalle's picture you will see he has a 3rd valve so when it is closed, he will NOT have a mess when removing the cap trying to drain.

See below https://www.valterra.com/product/twi...e-valve-boxed/

Still a lot of questions unanswered for me to try it. If I were to try I could simply do the same with my macerator pump acting as a 3rd valve.

[jimgossett2]

My 2014 Access Premier has the bathroom sink plumbed to the black water tank. Works great. I would see no problem doing that if you have the needed access.

[Wyatt]

Originally Posted by dkoldman

My manual says the same thing, heaven forbid a backup through the gray plumbing, the black is bad enough.

If you look at Nalle's picture you will see he has a 3rd valve so when it is closed, he will NOT have a mess when removing the cap trying to drain.

See below https://www.valterra.com/product/twi...e-valve-boxed/

Still a lot of questions unanswered for me to try it. If I were to try I could simply do the same with my macerator pump acting as a 3rd valve.

Sure he will. I have the same. type of setup. I used it to backflush the two tanks--separately. If he didn't have a hose connected to that "third" discharge, with the gath on it closed, once he opens either, or both of the other two, it will fluid will flow down and stop at that third gate he added. Once he opens that gate, whatever is backed up against the gate will come out...

[dkoldman]

Originally Posted by Wyatt

Sure he will. I have the same. type of setup. I used it to backflush the two tanks--separately. If he didn't have a hose connected to that "third" discharge, with the gath on it closed, once he opens either, or both of the other two, it will fluid will flow down and stop at that third gate he added. Once he opens that gate, whatever is backed up against the gate will come out...

If your system is exactly what Nalle has pictured there must be gap in understanding in what he was saying he was doing? I will let him chime if necessary, but my guess is that you are assuming the Intent.

Using your words...

once he opens either, or both of the other two, it will fluid will flow down and stop at that third gate he added. Once he opens that gate, whatever is backed up against the gate will come out

He would NEVER Open that 3rd Gate until he was ready to drain the tanks. There is a sewer end cap downstream of the 3rd gate.

The original suggestion to use the Twist Off valve from L1v3 was for coaches like mine that one had 2 valves. Gray & Black. If I did what was suggested to allow gravity to fill both tanks with both valves opened, then I would have waste fluids being held up by my sewer cap. Once I moved that Sewer Cap, I would have situation you seem to be referring to. But if I add a 3rd Valve, such as what Nalle is saying he has done, which his picture proves, he can simply have that 3rd valve closed while the other two valves are open. He will NOT have a mess, just possible contamination.

Further, I was saying I can do the same thing without a 3rd valve, because I can put my Flo jet macerator pump on and it will hold the waste water while both gray & black are open. In fact, I do this every time I dump. Difference is that I drain the black tank in full first. Leave the black tank open and then open the the gray and it backfills into the black. My macerator is OFF so at some point I shut down the gray and turn on the macerator and the gray waste that went into black waste tanks drains.

[Wyatt]

Originally Posted by dkoldman

If your system is exactly what Nalle has pictured there must be gap in understanding in what he was saying he was doing? I will let him chime if necessary, but my guess is that you are assuming the Intent.

He would NEVER Open that 3rd Gate until he was ready to drain the tanks. There is a sewer end cap downstream of the 3rd gate.

You're right. Looking at it again, I see that even though he'd have sewage behind the 3rd gate, it won't come out unless he opens that gate. Mine is the opposite. My backflush gate is downstream and would back up with fluids as soon as I opened either gray or black gate valves...

This is like brackish waters where the sea meets a river. Some of the saltwater goes upstream and some of the freshwater goes downstream, creating the brackish mix.

I can't imagine that just because one tank is more full than another, the gray water would just go over to the black tank, and everything would stop there.

In theory, the two should find equilibrium, and the tanks would be at the same level in both tanks (relative to earth), if the values were opened at the same time... Thoughts?

[dkoldman]

Originally Posted by Wyatt

I can't imagine that just because one tank is more full than another, the gray water would just go over to the black tank, and everything would stop there.

I never said this as stated, but tank with the greatest pressure head will push into the other tank.

In theory, the two should find equilibrium, and the tanks would be at the same level in both tanks (relative to earth), if the values were opened at the same time... Thoughts?

Yes the two tank vessels will find equilibrium, but it is assumptive where that equilibrium will be for each coach. Unless the tanks are the EXACT same size and at exact same height, yes they will be level in both tanks eventually regardless of pressure head.

Thus my question for those those that may have tried if they have any data?

I have 61 gal gray and 40 gal black. If I have 50 gal of water, it is assumptive to think that when they reach equilibrium in my case to have exactly 30 gal in gray and 20 gal in black(50% each). This is a test that I hope to do by draining and cleaning my black tank, then fill the gray to 61 gallons, In my case, I will add my macerator to be that 3rd valve and then open the black valve. Nothing should happen, I will then open the Gray valve. At that point I will see what my gauges read inside.

My Guess...

Gray goes from Full to just under 2/3rds =>35 gal
Black goes from Empty to 2/3rd =>26 gal


Again, it is a question? I plan to research unless somewhere has been there done that. It is possible based on actual tank position that black tank may consume 35 or more gallons of the available 61 gal from Gray

I am not an Adventurer, but that is my Intent anyway with the Sunstar

[Nalle]

Originally Posted by Wyatt

So I’m assuming you do this only when a hose is connected to the drain, right? Otherwise you’d have a mess on your hands—literally, once you take that cap offf…

My unit advises against that due to cross contamination…

No, hose does not have to be connected. The black handle added valve is completely tight and the twist on cap is just extra protection. True that if the valve should leak, there will be a minor mess. I have replaced all valves at least twice when they get too sticky and all seal well.
I have digital tank gauges and will only do a cross transfer when there is a substantial difference. Might be tough to see difference in tanks with the 1/3 tank gauges. Also, I can clearly hear when the transfer is complete and will close the black tank valve.
I leave the grey valve open and the added valve closed until dump time. Then I remove the twist cap and add the hose. Close grey valve and open added valve. A few cups of grey behind the added valve will drain and then I open black and drain. When black is done, I drain grey.
The way the plumbing is done, there should be no cross flow to grey.

[Nalle]

My tanks ate 52 Grey and 48 Black. And, yes, I will have both tanks valves open for a while when dumping. I have a clear pipe section on my hose and when I see black almost done, I open the grey.
Just for clarification, the twist on cap, in front of the added valve, is only on during driving. When stationary I trust the valves.
I also use a Probiotic Tank treatment and they recommend to not empty the tanks completely, as the stuff multiplies on it own.

[Morich]

I've been in a bit of turmoil here again and not fully plugged into looking at the forum. Life is getting complicated!
But when I've looked at what you are wanting to do, I've not gotten any good answers to suggest.
Study of the drawings seems to make connecting the two with any added pipes, etc. seem like really not good as it shows the black tank valve so far back and away from the final output that getting any line from grey to black would mean cutting into the black tank itself and I'm really not in favor of that!

The best I see is the idea of adding a valve as others suggest and that does have some questions, too.

It look like the two tank are both using pretty long outlet plumbing and the locations of the two tank outlets are nearly the same height!
What I'm seeing seems like the leveling of the RV would be critical when you opened the two existing valves to let grey run to black!
My thought is that if the RV is not at the correct level and black is slightly higher due to rear of RV higher, black may run to grey, instead of grey to black!
That gets me into thoughts of what extra effort is needed to keep the black solids from getting into the grey tank. What does that do for the overall work of keeping both clean?
A third valve at the outlet seems the best I see but with the questions of what it does for letting too much black go into the grey?
Part of my lack of getting involved in the thought is the way Microsoft is killing me on the forum things I've gotten used to doing. Many of the things I've used are no longer working or changed to the point that I am having to sort very carefully what and how to do things.
I am currently with Windows 10 and thank god I've not moved to 11 as I see what my wife is dealing with on it! But I've not gotten used to just finding things not working or not working the same as I had down!

How does business operate if they are not big enough to have an IT department and these sudden changes are just slamming them?
One item tying down lots of my time has been dealing with real estate and a closing company that can't move their paper until they get help to sort how things now work!
They thought they were being very progressive and getting all the new "improvements" but it has nearly killed their office.

So if I don't jump in with suggestions, I may just be learning how to find the right buttons!

[dkoldman]

Originally Posted by Morich

I've been in a bit of turmoil here again and not fully plugged into looking at the forum. Life is getting complicated!
But when I've looked at what you are wanting to do, I've not gotten any good answers to suggest.
Study of the drawings seems to make connecting the two with any added pipes, etc. seem like really not good as it shows the black tank valve so far back and away from the final output that getting any line from grey to black would mean cutting into the black tank itself and I'm really not in favor of that!

The best I see is the idea of adding a valve as others suggest and that does have some questions, too.

It look like the two tank are both using pretty long outlet plumbing and the locations of the two tank outlets are nearly the same height!
What I'm seeing seems like the leveling of the RV would be critical when you opened the two existing valves to let grey run to black!
My thought is that if the RV is not at the correct level and black is slightly higher due to rear of RV higher, black may run to grey, instead of grey to black!
That gets me into thoughts of what extra effort is needed to keep the black solids from getting into the grey tank. What does that do for the overall work of keeping both clean?
A third valve at the outlet seems the best I see but with the questions of what it does for letting too much black go into the grey?
Part of my lack of getting involved in the thought is the way Microsoft is killing me on the forum things I've gotten used to doing. Many of the things I've used are no longer working or changed to the point that I am having to sort very carefully what and how to do things.
I am currently with Windows 10 and thank god I've not moved to 11 as I see what my wife is dealing with on it! But I've not gotten used to just finding things not working or not working the same as I had down!

How does business operate if they are not big enough to have an IT department and these sudden changes are just slamming them?
One item tying down lots of my time has been dealing with real estate and a closing company that can't move their paper until they get help to sort how things now work!
They thought they were being very progressive and getting all the new "improvements" but it has nearly killed their office.

So if I don't jump in with suggestions, I may just be learning how to find the right buttons!

My employer recently forced us all from Google Mail, Drive etc. to Microsoft Outlook, One Drive, Sharepoint, Teams etc and what a pain. Given your woes, I decided to do what you have taught me to do just to show I am capable of listening sometimes

This is what it looks like.


Originally I wanted to simply add a ball valve right under the sink to have a Y that T's off direct to the black tank. Yes a hole would have to be cut into the black tank. The problem is getting to it without cutting a hole in the floor. It may be easier to access where sink drains run underneath the shower, if I can get my Mobile Tech or a plumber to put a valve there it may work. Just a pain to access to switch it back and forth.

Right now I am using the contingency bowl in the bath to see how well it works. Thus far it has been easy to use but no trips to test. I am just testing things out at home now. Another very important factor is that we recently replaced that momentary switch in outdoor kitchen with a more practical On/Off. https://www.winnieowners.com/forums/...en-367204.html I just have a feeling that outdoor sink will get used a lot more now. Wow it is night and day. Just washing your hands was shore with the momentary switch. Since that sink drains to black tank, the impact is TBD.

I have my doubts on the opening both gray and black at the same time to stabilize. I don't know how you can do that without contamination. But before I get into that details, I need to know what it is doing now to see what that gain might be? I don't want situation where I make it worse or flip the script on the original problem and now having the black almost full versus having the gray almost full.

I described a test plan earlier, so until I get around to doing that and calculating what 61 gallons of fresh water looks like stabilized in both gray and black tank. I can get the exact gallons even though my gauges read in 1/3rds. I know the size of my tank, I have a flowmeter so when tank stabilize, I can just see how many gallons it takes to go to full and do the math to calculate both tanks.

[Morich]

Whoopee!
After about 48 hours of playing and reading of the instructions that are no longer right for using the snipping function they have added to Windows, I got part of my problem solved!
I could snip but with some real effort as hitting three keys at once is a trick for a guy would runs a keyboard like me!!!
Windows key, shift and "S" are not handy for me! But then the question was finding what it did?? Did it not work, or where did it take the snip as there was no "save" tab??

DUH! I finally stumbled onto it being put on my clipboard and I could then move it to something like Paint or Adobe to do the markups that I was able to do on my older "snip and sketch"! Awkward and it may get better but it was a real trick to find the path to follow as many of the directions I was finding did not give me a clue!
Just gotta know that , I guess?

But it does let me do some thinking to throw out for you to look over?
I think I see a cabinet under the vanity and that may mean there is an access flap already cut under that cabinet?? My Vista had one, once I found it!
So the big check might be to look if there is an access and if it lets you get enough space to think of mod to the pipe from the vanity down and tie into the large drain from the black tank, BEFORE the existing drain valve?
Click for better view!

Questions?
Do you have a cabinet as I outlined in black with an opening along the red line? Find the basin drain, tie into it and wiggle a path down to the main black tank drain before the existing valve? Yellow line for new pipe?

Maybe work in a valve to give the option of which tank to run the basin water into? Or maybe just stop adding water down that drain at the right time to stop?

There is a handy gizmo called a "saddle drain valve" which might be handy here?
The idea is that the saddle is fit over the PVC pipe with bolts and then a hole is drilled to let the new pipe join the existing without cutting and fitting the existing back together. That is a trick when you can't move either side of an existing pipe!
I used them several times when doing my rental mods/repairs/rebuilds!

This is NOT the right size but they did come in big sizes to fit 3-4 inch pipe. More shopping??
Stole this pic from Home Depot but was a common plumbing part ten years a go??

[Nalle]

Just to clarify a few things and maybe add to the confusion........

1. I will only use the Gray to Black transfer when there is a substantial difference in tank levels. Then gravity works very well!!

2. With the third added valve closed, I will open the Gray. Now the black valve has Black water on one side and Gray on the other. Opening the Black tank valve will now definitely force Gray in to the Black. Once the transfer is complete, close the Black valve. It only takes a few seconds. If done right, I doubt there will be any Black tank stuff behind the third added valve.

3. If the tanks are side by side, I doubt that being slightly off level makes much difference. If tanks are far apart, it will.

4. For years I was thinking about how to transfer from Gray to Black. Pumps and switches, ball valves and stuff. Everything too complicated.

5. For anything RV, the KISS principle seems to always work best. Keep It Simple, Stupid. The third valve is surely cheap and simple and easy to reverse in not working properly.

6. This is only the second summer using this system and I have only had need to use it maybe 3-4 times every summer. I will only used it with minimum 70-75% gray and with a maximum 40% black. I.e. a Delta of at least 30% and preferably more. It has always worked great and no issues.

7. If concerned about backflow of Black, after the transfer and after closing the Black valve, get a bucket and close also the Gray valve. Open the third added valve and capture the small amount of waste now locked in between the Gray and Black valves. Should not be much more than a pint to a quarter gallon that you can pour down the toilet. My bet is that it is only Gray water.

[dkoldman]

Originally Posted by Nalle

Just to clarify a few things and maybe add to the confusion........

1. I will only use the Gray to Black transfer when there is a substantial difference in tank levels. Then gravity works very well!!

2. With the third added valve closed, I will open the Gray. Now the black valve has Black water on one side and Gray on the other. Opening the Black tank valve will now definitely force Gray in to the Black. Once the transfer is complete, close the Black valve. It only takes a few seconds. If done right, I doubt there will be any Black tank stuff behind the third added valve.

3. If the tanks are side by side, I doubt that being slightly off level makes much difference. If tanks are far apart, it will.

4. For years I was thinking about how to transfer from Gray to Black. Pumps and switches, ball valves and stuff. Everything too complicated.

5. For anything RV, the KISS principle seems to always work best. Keep It Simple, Stupid. The third valve is surely cheap and simple and easy to reverse in not working properly.

6. This is only the second summer using this system and I have only had need to use it maybe 3-4 times every summer. I will only used it with minimum 70-75% gray and with a maximum 40% black. I.e. a Delta of at least 30% and preferably more. It has always worked great and no issues.

7. If concerned about backflow of Black, after the transfer and after closing the Black valve, get a bucket and close also the Gray valve. Open the third added valve and capture the small amount of waste now locked in between the Gray and Black valves. Should not be much more than a pint to a quarter gallon that you can pour down the toilet. My bet is that it is only Gray water.

All of the above is clear to me, but #6 is open question as to how much or how many gallons ultimately transfer from Gray when you are 70 - 75% full to a black tank that may already be at 40% full.

In my case. until I do the research ( validation test) on my coach I don't know definitively what value ( gain in gallons) I might be achieving if any? If someone has done with 29ve it may save me some testing.

Also, I follow your logic to try to avert black waste from back flowing to gray, but it still counters the manual and has some risks.

Also just so you know, the way I do this now... BEFORE this thread was created, is that I simply connect my Flo Jet macerator pump up like normal and take the 25' orange waste hose and take to the toilet and flip the pump. I turn the pump off when black tank hits 2/3rd full.

But since this thread I have made two new changes.

1. Replaced outdoor kitchen momentary switch with simple ON/OFF to make it easier to use the outdoor sink to wash hands and other objects ( dishes) and this is pumped to the black so black tank usage will grow.
2. Contingency bowl in the Bath; so when washing hands in the bath sink, we can optionally dump into toilet

Of course my ultimate solution is the intent of thread to modify plumbing from bath sink to optionally direct to black tank

The idea to gravity force some gray into black tank is a 4th possible workaround, but as stated before, I need to quantify that benefit given the risk of contamination before willfully defying what WBGO knows and have documented in my manual. This weekend I may take a few pictures of how I can pump from Gray to Black fairly easily.

With all that said, if I could pay $500 or less and have a professional job performed, I would gladly pay to have my bath sink fitted with a valve to optionally divert to black. It is miss by WBGO IMO based on how we use the coach. A diverter valve gives owners greater flexibility for their needs.

[Nalle]

Originally Posted by dkoldman

All of the above is clear to me, but #6 is open question as to how much or how many gallons ultimately transfer from Gray when you are 70 - 75% full to a black tank that may already be at 40% full.

In my case. until I do the research ( validation test) on my coach I don't know definitively what value ( gain in gallons) I might be achieving if any? If someone has done with 29ve it may save me some testing.

Also, I follow your logic to try to avert black waste from back flowing to gray, but it still counters the manual and has some risks.

Also just so you know, the way I do this now... BEFORE this thread was created, is that I simply connect my Flo Jet macerator pump up like normal and take the 25' orange waste hose and take to the toilet and flip the pump. I turn the pump off when black tank hits 2/3rd full.

But since this thread I have made two new changes.

1. Replaced outdoor kitchen momentary switch with simple ON/OFF to make it easier to use the outdoor sink to wash hands and other objects ( dishes) and this is pumped to the black so black tank usage will grow.
2. Contingency bowl in the Bath; so when washing hands in the bath sink, we can optionally dump into toilet

Of course my ultimate solution is the intent of thread to modify plumbing from bath sink to optionally direct to black tank

The idea to gravity force some gray into black tank is a 4th possible workaround, but as stated before, I need to quantify that benefit given the risk of contamination before willfully defying what WBGO knows and have documented in my manual. This weekend I may take a few pictures of how I can pump from Gray to Black fairly easily.

With all that said, if I could pay $500 or less and have a professional job performed, I would gladly pay to have my bath sink fitted with a valve to optionally divert to black. It is miss by WBGO IMO based on how we use the coach. A diverter valve gives owners greater flexibility for their needs.

You are right about the 70-75 Gray/ 40 Black comment. In my case it works fine because I have installed digital gauges on both tanks and the percentage readings actually compare liquid height in each tank. Since one tank is slightly wider than the other, after transfer the percentage change is not exactly the same.

[Nalle]

Here is a picture of the gauge installation