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Merging grey tanks, is it possible?

omextreme
Explorer
Explorer
Just a curious idea.

We are camping without sewer for the next 5 days, Our black tank will hold just fine but the grey tank for the shower will be an issue. We have 2 grey tanks 1 for shower and bath sink and the other is the kitchen and outdoor kitchen.

Here is my question. Both tanks have their own dump valve, both tanks are at the same height on the frame. And both tanks merge into the same pvc sewer pipe to exit the camper.

My Question is could I buy one of those gate valves that lock on to the end of the trailer sewer connection, close it and open the 2 dump valves on the grey tanks?

My theory is that both tanks would fill at the same time essentially doubling my shower water capacity, Kind of like a water level.

This seems to me like a great simple idea which probably means I am missing something.

Thanks for any advise
17 REPLIES 17

TakingThe5th
Explorer
Explorer
shepstone wrote:
TakingThe5th wrote:
I also have 2 grey tanks. This would be a longer range solution for you, but I added a pump that uses the shower/bath sink water to flush the toilet. I now use less fresh water and the grey tank fills up slower. I don't use the kitchen grey water but the shower water does not smell and is suitable for flushing.

Great Idea how did you go about it?


The grey water flush system is actually quite simple. We have a new tap in the grey water tank and a demand-type water pump and a filter to catch hair and other small debris that could clog the pump. We cut into the fresh water supply for the toilet and added valves and tees so we could select between fresh water and grey water. Check valves were added to make sure no grey water could contaminate the fresh water. We are very happy with the outcome.
TakingThe5th - Chicago, Western Suburbs
'05 Ford F350 Crew 6.0 DRW Bulletproofed. Pullrite Super 5th 18K 2100 hitch.
'13 Keystone Cougar 333MKS, Maxxfan 7500, Progressive EMS-HW50C, Grey Water System.

shepstone
Explorer
Explorer
TakingThe5th wrote:
I also have 2 grey tanks. This would be a longer range solution for you, but I added a pump that uses the shower/bath sink water to flush the toilet. I now use less fresh water and the grey tank fills up slower. I don't use the kitchen grey water but the shower water does not smell and is suitable for flushing.

Great Idea how did you go about it?
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TakingThe5th
Explorer
Explorer
I also have 2 grey tanks. This would be a longer range solution for you, but I added a pump that uses the shower/bath sink water to flush the toilet. I now use less fresh water and the grey tank fills up slower. I don't use the kitchen grey water but the shower water does not smell and is suitable for flushing.
TakingThe5th - Chicago, Western Suburbs
'05 Ford F350 Crew 6.0 DRW Bulletproofed. Pullrite Super 5th 18K 2100 hitch.
'13 Keystone Cougar 333MKS, Maxxfan 7500, Progressive EMS-HW50C, Grey Water System.

christopherglen
Explorer
Explorer
You can sterilize the grey after dumping, pour 1/2 gallon of bleach (far more then needed, but no open bottles to store) in each grey tank after dumping, and fill with water, let set overnight, then dump (not into septic) at a dump station. Kills anything in the grey tanks, and you can dump in forests again (where legal).
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laknox
Nomad
Nomad
Personally, I'd never merge my black and grey tanks except in an emergency. Here in AZ, at least, it is legal to dump a grey tank in the forest, but completely illegal for black. The forests need the water, so I'd have no issue at all with the grey, but if you merge the tanks, then you can't dump either except in a regular dump station...legally.

Lyle
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laknox
Nomad
Nomad
omextreme wrote:
rhagfo wrote:
I going just ask how many using the shower?? DW and I have gone 8 days on out Grey tank. It is just a matter of using water conservation. That was with both of us taking daily showers.


4 showering. 2 - 5 yr old boys that like the dirt.

We may be fine but this will be the first longer test of the new trailer and we are not sure how much water we are using yet....


Don't you have an outside shower? Use that for the kids. Tell 'em that if they misbehave you won't turn on the hot water. 🙂 Used that one year when a grand-nephew was being a little sh!t and playing in the mud, just to spite his parents. Guess what? He stopped playing in the mud! Water tank at 7,000', even in August, isn't any too warm. 🙂

Lyle
2022 GMC Sierra 3500 HD Denali Crew Cab 4x4 Duramax
B&W OEM Companion & Gooseneck Kit
2017 KZ Durango 1500 D277RLT
1936 John Deere Model A
International Flying Farmers 64 Year Member

rhagfo
Explorer III
Explorer III
omextreme wrote:
rhagfo wrote:
I going just ask how many using the shower?? DW and I have gone 8 days on out Grey tank. It is just a matter of using water conservation. That was with both of us taking daily showers.


4 showering. 2 - 5 yr old boys that like the dirt.

We may be fine but this will be the first longer test of the new trailer and we are not sure how much water we are using yet....


I am sorry, I don't think they make tanks that big!!! :B :S
Russ & Paula the Beagle Belle.
2016 Ram Laramie 3500 Aisin DRW 4X4 Long bed.
2005 Copper Canyon 293 FWSLS, 32' GVWR 12,360#

"Visit and Enjoy Oregon State Parks"

omextreme
Explorer
Explorer
rhagfo wrote:
I going just ask how many using the shower?? DW and I have gone 8 days on out Grey tank. It is just a matter of using water conservation. That was with both of us taking daily showers.


4 showering. 2 - 5 yr old boys that like the dirt.

We may be fine but this will be the first longer test of the new trailer and we are not sure how much water we are using yet....

rhagfo
Explorer III
Explorer III
I going just ask how many using the shower?? DW and I have gone 8 days on out Grey tank. It is just a matter of using water conservation. That was with both of us taking daily showers.
Russ & Paula the Beagle Belle.
2016 Ram Laramie 3500 Aisin DRW 4X4 Long bed.
2005 Copper Canyon 293 FWSLS, 32' GVWR 12,360#

"Visit and Enjoy Oregon State Parks"

Old-Biscuit
Explorer III
Explorer III
I installed an 'extra' valve on main drain header that all three tanks use.
With it closed I open both grey tank drain valves equalizing them. 50 grey and 28 galley for total of 78 grey

And with it closed I can even open black tank and equalize all three tanks for 128 gallons total capacity.

Yes black and grey combined.........it's all waste water and grey can stink worst then black
Was a time RVs had just one tank. Waste is waste and gets dumped into same place.
Is it time for your medication or mine?


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TucsonJim
Explorer
Explorer
Another nice feature of having the Valterra valve on the dump outlet is that if any of your tank valves have a leak, you won't get a nasty shower when you pull the cap off to dump. BTW, I use one the valve to equalize our tanks too.
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Hvyhauler
Explorer
Explorer
It works for me... I've used this procedure before.I use a Valtera part # T58 twist on 3" waste valve (aka gate valve) and keep it capped on the end until dumping time.

As others have said don't open the black tank valve while using this process.
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JesLookin
Explorer
Explorer
I glued one of those valves to the output, now share gray tanks with no problems
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2014 Ram 3500 6.7L CTD, Crew Cab

bg71361
Explorer
Explorer
I accomplished it by using this, install it closed and the pull both grey tank levers tanks will equalize. See link

Click here