# Gray Water Tank Sizes



## Phil N (Aug 4, 2015)

I have a 2011 Outback 301BQ. 
This unit has two gray water tanks.
Anyone know the respective sizes of each?
The manual only indicates 60 gallons total.

It would be nice to know since my forward tank (which only holds the front sink drainage)seems to fill quite soon.

Thanks


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## Todd&Regan (Jul 1, 2010)

30 gallons each: 1 for the kitchen sink, 1 for the bathroom sink and shower.

Todd


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## deepvee16 (Jan 27, 2014)

Todd&Regan said:


> 30 gallons each: 1 for the kitchen sink, 1 for the bathroom sink and shower.
> 
> Todd


Yep, that's how it is for our 298re. We have found that we accumulate very little in the grey tank that serves the galley sink. But, the bathroom is a different story, especially when using the shower. 
I bought one of these valves  at Camping World, it effectively doubles our grey water capacity. I put it on only when we're dry camping, not while on the road (it hangs too low). Just put it on in the closed position, then open both grey valves. Since water seeks its own level, the two tanks "share". When it's time to dump, close both grey valves, then place a bucket under this new valve, there will be about 1/2 gallon residual. Take off the new valve and dump as usual. Word of caution, ALWAYS KEEP BLACK CLOSED, you don't want to mix any black with the grey. 
This thing costs about $20- and it works great.


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## MO7Bs (Apr 11, 2009)

deepvee16 said:


> 30 gallons each: 1 for the kitchen sink, 1 for the bathroom sink and shower.
> 
> Todd


Yep, that's how it is for our 298re. We have found that we accumulate very little in the grey tank that serves the galley sink. But, the bathroom is a different story, especially when using the shower. 
I bought one of these valves  at Camping World, it effectively doubles our grey water capacity. I put it on only when we're dry camping, not while on the road (it hangs too low). Just put it on in the closed position, then open both grey valves. Since water seeks its own level, the two tanks "share". When it's time to dump, close both grey valves, then place a bucket under this new valve, there will be about 1/2 gallon residual. Take off the new valve and dump as usual. Word of caution, ALWAYS KEEP BLACK CLOSED, you don't want to mix any black with the grey. 
This thing costs about $20- and it works great.
[/quote]

I too use a supplemental valve. However I use this one. I like being able to back flush my tanks, see that they are clean and know when they are truly empty. When using it to max out the grey water capacity you don't need a bucket, just hook up the sewer line and let it rip.


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## Phil N (Aug 4, 2015)

Thanks for the info.

Not fully understanding how the supplemental valve works. 
Do you buy two valves? One for each gray water drain? 
Assuming the two tanks are totally independent with their own drains it would seem to me that there would have to be a hose connecting the two drains so the tank levels would balance out.


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## deepvee16 (Jan 27, 2014)

Phil N said:


> Thanks for the info.
> 
> Not fully understanding how the supplemental valve works.
> Do you buy two valves? One for each gray water drain?
> Assuming the two tanks are totally independent with their own drains it would seem to me that there would have to be a hose connecting the two drains so the tank levels would balance out.


Sorry, I made the assumption that you have a single discharge for all three tanks as we do. Here's a somewhat lousy photo of our auxilliary valve hooked up. 
There's no advantage for us to do this when we have full hook up, or dry camping for that matter since we only hold 37 gallons of fresh water. As you can see from the photo, I need to remember to disconnect before driving. 
I hope this makes better sense now. 
Dave


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