# Grey And Black Water Tank Fullness - A Very Uncontrolled Experiment



## thefulminator (Aug 8, 2007)

We are always shocked to see how quickly the guage on the grey and black water tanks say the are getting full. Since I have the Outback at home and it's pretty level with empty tanks, it was time to do an experiment.

Using a 2 gallon bucket in the tub, I poured 2 gallons of water at a time down the tub drain checking the tanks levels between each bucket. I repeated the process dumping the water down the toilet. We have the standard 40 gallon tanks. Here are the results.

Grey
(6) gallons = 1/3 full
(18) gallons = 2/3 full
(36) gallons = full

Black
(4) gallons = 1/3 full
(14) gallons = 2/3 full
(30) gallons = full

I guess Gilligan strikes again. Your results may vary...........................


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## Ridgway-Rangers (Apr 18, 2008)

I'm adding a tornado flush this weekend. At least your black tank guage works. Mine has read full for about a month. I've been using the wand but looking forward to nat dragging the hose through tthe TT.


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## Oregon_Camper (Sep 13, 2004)

The results you are showing are what the guage read...right?

Did you continue to fill the toilet and see if it really did hold 40 gallons?

Or...with the 30 gallons in the Black tank...drop in 2-3 bags of ice and drive the trailer around. This will help scrub the inside of the tank.


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## FLYakman (Jan 26, 2006)

I had to laugh when you wrote "standard 40 gallon tanks"

Don't know about 2009 model year but 2010 model year has 30 gal. black and grey. I guess that means I really have 25 gal tanks based on your test. I did fill the grey tank to the top of the kitchen sink drain once during our western trip. That never happened when we had the '06 23RS.


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## Avbird (Jun 1, 2009)

My tanks on a 2004 25 rss are the same, the minute I put anything in the black tank it goes to 2/3 and it reads full most of the time even after I empty it. I can get it to E with a couple of runs with the flush king. The sensor must be in a terrible location. My inlaws have a Cougar, same deal. They also have tons of friends with $100,000 rv's and its the same. Someone suggested on here to put calgon bath scrub in the tank to clean it out. That and 5 gallons of hot water before a road trip apears to scrub the tank great. No smell for a while after that! Great experiment, I had been contimplating the same.


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## SDCampers (Oct 29, 2008)

Rayman said:


> I had to laugh when you wrote "standard 40 gallon tanks"
> 
> Don't know about 2009 model year but 2010 model year has 30 gal. black and grey. I guess that means I really have 25 gal tanks based on your test. I did fill the grey tank to the top of the kitchen sink drain once during our western trip. That never happened when we had the '06 23RS.


The 2010 models are "ultra lights" as opposed to "lights" thus they switched to 30 gal grey and black. The 2009's have 40 gal grey and black. That was a deciding point for me to get the 2009 instead of a 2010.


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## hyewalt34 (May 9, 2004)

Consider yourself lucky with those tanks: My 2004 21rs has 20 gal. black and grey tanks.

Walter


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## FLYakman (Jan 26, 2006)

SDCampers said:


> I had to laugh when you wrote "standard 40 gallon tanks"
> 
> Don't know about 2009 model year but 2010 model year has 30 gal. black and grey. I guess that means I really have 25 gal tanks based on your test. I did fill the grey tank to the top of the kitchen sink drain once during our western trip. That never happened when we had the '06 23RS.


The 2010 models are "ultra lights" as opposed to "lights" thus they switched to 30 gal grey and black. The 2009's have 40 gal grey and black. That was a deciding point for me to get the 2009 instead of a 2010.
[/quote]

Thanks.I did not know that. Although I really did not have a choice at the time I bought it. I'll just have to watch it more closely.


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## Calvin&Hobbes (May 24, 2006)

Oregon_Camper said:


> The results you are showing are what the guage read...right?
> 
> Did you continue to fill the toilet and see if it really did hold 40 gallons?
> 
> Or...with the 30 gallons in the Black tank...drop in 2-3 bags of ice and drive the trailer around. This will help scrub the inside of the tank.


The ice trick does a nice job "scrubbing" the insides of the tank. But a bit of advice... When pouring the ice down the toilet, do it very SLOWLY. I just dumped it in the bowl, and almost imediatley had just a bowl of ice. I tried to shift the ice around, and get it past the valve... to no avail. When we returned from our 4 hour trip, I still had a big bowl of ice. The next time I broke the bags up good and gently poured it in!

Our indicators are a bit wacky as well. I have emptied all tanks, and then added a 3 gallon bucket of calgon and deodorant with hot water, and showed 1/3 full. On a 40 gallon tank, I should have had about 13 gallons in there for that reading.


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## russk42 (Sep 10, 2007)

Rayman said:


> I had to laugh when you wrote "standard 40 gallon tanks"
> 
> Don't know about 2009 model year but 2010 model year has 30 gal. black and grey. I guess that means I really have 25 gal tanks based on your test. I did fill the grey tank to the top of the kitchen sink drain once during our western trip. That never happened when we had the '06 23RS.


And what happened in the tub, when you were full to the top of the sink drain?


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## Calvin&Hobbes (May 24, 2006)

russk42 said:


> I had to laugh when you wrote "standard 40 gallon tanks"
> 
> Don't know about 2009 model year but 2010 model year has 30 gal. black and grey. I guess that means I really have 25 gal tanks based on your test. I did fill the grey tank to the top of the kitchen sink drain once during our western trip. That never happened when we had the '06 23RS.


And what happened in the tub, when you were full to the top of the sink drain?








[/quote]

That became a wading pool.


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## tdvffjohn (Mar 10, 2005)

Interesting.......now, how much free time do you actually have?


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## Doxie-Doglover-Too (Jan 25, 2007)

The ice trick does a nice job "scrubbing" the insides of the tank. But a bit of advice... When pouring the ice down the toilet, do it very SLOWLY. I just dumped it in the bowl, and almost imediatley had just a bowl of ice. I tried to shift the ice around, and get it past the valve... to no avail. When we returned from our 4 hour trip, I still had a big bowl of ice. The next time I broke the bags up good and gently poured it in!

[/quote]

Ditto! to a T! we did the ice thing one time and were amazed at what "extra" came out when we reached our destination and dumped.


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## thefulminator (Aug 8, 2007)

I personally don't believe in the ice scrubbing the black tank idea. This is from when I installed a turbo rinser in the black tank and was able to see the contour of the tank. The bottom is not flat. It has enough slope to the drain that in my opinion, the ice won't move around unless you are taking corners way too fast. I've heard some say to add some water so the ice will float. My question is, how much? Too little and the ice just sits in the drain well of the tank. Too much and it floats above the bottom of the tank. I'll stick to the turbo rinser until my nose tells me to do otherwise.

Here is an example of the slope I am trying to describe.


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## Doxie-Doglover-Too (Jan 25, 2007)

thefulminator said:


> I personally don't believe in the ice scrubbing the black tank idea. This is from when I installed a turbo rinser in the black tank and was able to see the contour of the tank. The bottom is not flat. It has enough slope to the drain that in my opinion, the ice won't move around unless you are taking corners way too fast. I've heard some say to add some water so the ice will float. My question is, how much? Too little and the ice just sits in the drain well of the tank. Too much and it floats above the bottom of the tank. I'll stick to the turbo rinser until my nose tells me to do otherwise.
> 
> Here is an example of the slope I am trying to describe.


we only did the ice once, when our noses told us to







. Put in a couple gallons of water, a bag of ice, and it worked like a charm.


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