Community Forums

red7654 · 11-28-2020, 08:36 AM

Good Morning!
This isn't urgent just something I would like to know.
I have read through all of the manuals and I can't find anywhere how big the black tank or gray water tank is. Is there any place I can look this up on the Internet? Short of pouring 5 gallons of water at a time into the tanks I have no idea!
Thanks

groswald · 11-28-2020, 08:46 AM

It would help to know year, make, and model of your RV.

That said, do a google search for your year, make, model, and “specifications”. You may have to wade through a bunch of junk, but will probably find them.

Regards,

Randy

AnotherMike · 11-28-2020, 09:11 AM

First of all, you need to include or post the year, make and model of your RV... someone reading your posting may have the same RV... if you add it to your signature lines then it will be automatically added to the end of each posting...

To answer your question...
If you are going to use the fill-it-up method then this will help...

https: // www.walmart.com/ip/P3-International-P0550-Save-A-Drop-Water-Meter/19885585

I've also seen it on Amazon and a few years ago at big orange (Home Depot)...

Next, if you have physical access to the tanks, and if they are square sided then it's fairly easy... I used this method with my Class A... (shades of 1960s grade school math and high school physics)...

I'll use my fresh water tank as an example...
The tape measure says the outside dimensions are 22.5 inches wide by 15.5 inches high by 44.5 inches deep

22.5 times 15.5 times 44.5 is 15519.375 cubic inches

15519 divided by 231 (the number of cubic inches in a gallon) = 67.18
but we are using outside dimensions for simplicity and that ignores the thickness of the tank walls... and the thickness (especially of the bottom and the sides) reduces the volume... so call it around 65-66 gallons.

If you have a tank with an odd shape that can be approximated with multiple cubes, i.e. a smaller cube on top of a larger cube, or a small cube on the end of a large cube then you can calculate the volume of each section and then add the resulting numbers...
Some black and grey tanks are tapered on the bottom with the "fat" end or low point at the drain fitting (to assist in dumping)... just measure the height of the short end and the height of the tall end and split the difference. the volume will not be exact, but it will be usable.

A few months after I calculated 65-66 gallons I found a old brochure from the vintage of my coach and it said 65 gallons. Close enough...

Later on using a meter (like the one shown in the walmart webpage above) I found that it overflowed right around 62 and a half... Must have shrunk with age... Or maybe the overflow tube location cost some volume. Or maybe the marketing weasels rounded the numbers up...

Mike

rk911 · 11-28-2020, 10:36 AM

Quote:

Originally Posted by groswald

It would help to know year, make, and model of your RV.

That said, do a google search for your year, make, model, and “specifications”. You may have to wade through a bunch of junk, but will probably find them.

Regards,

Randy

+1 on this or contact the mfg customer service department and get a copy of the 'build sheet' for your specific RV.

Alan_Hepburn · 11-28-2020, 03:42 PM

Somewhere in your RV there should be a data sheet that has that information printed on it. Ours, a 2007 Bounder, has it glued to the wall inside the bedroom wardrobe closet...

JFXG · 11-29-2020, 07:14 PM

red..... you did not ask about your fresh water tank. Do you know that quantity? As a VERY general rule of thumb your gray tank might be about 60 to 65% of your fresh capacity, and your black May be about 35 to 40%.

Skip426 · 11-29-2020, 07:26 PM

Red , has set up a signature line for his RV , but must have posted this question using a phone app, and when using the app , signature lines don't show with the posts .

TT, 2004 Crossroads 28'

I'll go with ; JFXG 's ; assessment 60 % of fresh capacity for grey , and 40 % for black . That's my set up.