2 gray tanks - how big is each one?

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quadna71

quadna71

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Our 2020 Forest River 22RBHL has 2 gray tanks - 1 for the bathroom sink/shower and one for the kitchen sink.  The specs that I've been able to find online all repeat "64 gallons total" but never seem to split the total to say how big each one is.  Any idea of a website I can find to figure that out?  We took it out for it's maiden 3-night trip to our local state park and the bathroom gray tank filled up surprisingly fast compared to our old camper, and it is only my wife and I.  We follow all the normal rules of shutting off the shower head when not rinsing and keeping the faucets only turned on enough to get the job done but still cut it close. Either way, I'm not sure how to determine the individual sizes.  I don't even have a portable drain tank for emptying mid-weekend or else I'd try some variation of the water bottle measurement scenario out of Die Hard 3  ;D

Here's our camper:  https://forestriverinc.com/rvs/travel-trailers/heritage-glen-hyper-lyte/22RBHL/4482

 
Kitchen is likely 20 gallons,  the shower and bath sink gets the rest.
 
donn's guess is likely on-target, but most anything is possible. The tank sizes are typically dictated more by available space than anything else.

The actual size in gallons isn't important anyway - just the days between dumping and that's dependent on your water usage habits. It is what it is.  If your curiosity demands an answer, all you need is a bucket with gallon markings, usually available cheaply at any dollar store or Walmart.  .  Run fresh water down the the kitchen sink until the tank gets full.  Then open the dump valve for the tank and let it run into the bucket to the gallonage mark and shut off the dump valve. Empty the [clean] water anywhere convenient and repeat until you have the total gallonage.

Be aware that the rated size of the tanks is typically greater than actual use capacity. The tank capacity numbers are as stated by the tank manufacturer for a 100% full tank on a work bench. Usually when installed the plumbing inlet & outlet locations don't allow the tank to be 100% full. I've seen some as low as 80% of theoretical max capacity.
 
Gary RV_Wizard said:
donn's guess is likely on-target, but most anything is possible. The tank sizes are typically dictated more by available space than anything else.

The actual size in gallons isn't important anyway - just the days between dumping and that's dependent on your water usage habits. It is what it is.  If your curiosity demands an answer, all you need is a bucket with gallon markings, usually available cheaply at any dollar store or Walmart.  .  Run fresh water down the the kitchen sink until the tank gets full.  Then open the dump valve for the tank and let it run into the bucket to the gallonage mark and shut off the dump valve. Empty the [clean] water anywhere convenient and repeat until you have the total gallonage.

Be aware that the rated size of the tanks is typically greater than actual use capacity. The tank capacity numbers are as stated by the tank manufacturer for a 100% full tank on a work bench. Usually when installed the plumbing inlet & outlet locations don't allow the tank to be 100% full. I've seen some as low as 80% of theoretical max capacity.
Click to expand...

I guess I was hoping someone might already know the answer so that I wouldn't have to go through the steps you listed.  Plus it would be helpful to know if I end up purchasing a rolling tank for emptying mid-weekend....no need to purchase larger than necessary. 
 
If you can measure the tank's dimensions, you can use them to figure the capacity.  A gallon is 231 cubic inches so multiplying the tank's Length x Width x Depth in inches and dividing by 231 will give the tank's capacity in gallons.

Drain tanks usually slope towards the drain, so you'll have to measure the depth at both ends and take an average.
 
Another possible clue is the grey water capacity is exactly double the black water capacity (64 gallons vs 32 gallons).  It's very likely Forest River just installed 3 tanks of the same size, two for grey water and one for black.  So you'd have 32 gallons grey water storage for the kitchen and 32 gallons for the bathroom.

Does your trailer have one sewer outlet or two?  My Arctic Fox trailer came to a single sewer fitting and each grey tank had a dump valve at the output of the tank and a third one where the two tanks came together at the outlet.  If I left both tank valves open and the third valve closed the two grey tanks functioned as one large tank, self equalizing between them.

If you do this, you want to close the individual tank valves while travelling or when you go up or downhill the higher tank can overfill the lower one.
 
Browse on a Forest River Forum, I'd bet someone with your exact model knows  ;)

My limited search found only one gray tank  :eek:
 
An inexpensive flow meter on the city water hose could easily tell you exactly how much water each tank holds.
 
We have two gray tanks on our 5th wheel Jaco with total capacity of 64 gallons just like yours. Each one is 32 gallons and same set up as your for bathroom and kitchen. I could not find the information in the manual or on line, So I called the manufacturer with my Vin number and they looked it up told me. Other suggestion would be to use a bucket and pour clean water in the tank and then look at the gauge and see how much it takes to fill it to 1/3 or 1/2, which should be a good indication. I used this method to validate mine.
 
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