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myredracer's avatar
myredracer
Explorer II
Sep 15, 2018

Total holding tank volume for two gray tanks? UPDATE

I had to pull down the underbelly coroplast recently due to an overflowing toilet. (:M)

I found that the gray tank for the bathroom is 20 gallons (per sticker on the tank). The printed factory brochure volume for our galley + bathroom gray tanks is listed as 60 gallons. So does that mean we have a 40 gallon galley tank and a 20 for the bathroom? Seems odd.

The online factory brochure is slightly different and says the total gray tank volume is 64 gallons which would suggest 2 x 32 gallon tanks. That would also be the same as the black tank.

Did the factory screw up or short change us? Our black tank is 32 gallons per the factory info. I would like to see what the sticker on the galley tank says but it's a real b*tch of a job taking the coroplast down and putting it back up. I could use a 5 gallon container and see how many times it takes to fill the tank up with water.

Wouldn't you want the bathroom tank larger because of the amount of water used for showering?
  • Look for “We reserve the right to modify specifications” in your owner's manual.
  • The simple way to determine is just get a 3 or 5 gallon bucket and fill the tank enough times to match what you think. Doug
  • Our rear kitchen 5er had the smaller grey tank at the back with its own dump valve that led to the main dump valve. The big grey tank up closer to the bathroom had its own valve.

    I confirmed the amount each tank could hold individually using buckets at the dump valve after filling the tanks by running taps. "Full" is when the water comes up into the kitchen sink for the galley grey and up into the bathtub for its grey tank.

    I didn't like to mix the two tanks by leaving valves open because the galley grey water is nasty, while the bathroom grey is clean soapy, so it is good for being the last to dump and clean the sewer hose.

    While off grid, the galley grey always filled first, so I would have preferred it be the big one.
  • That's a pretty standard setup - 20/40 except it was 40 for the shower/bath. We had the same combination on our last RV. Our present TT has a single 60 gallon grey tank. So it's really the same capacity.

    If yours is backwards from this, you could always install a valeve at the dump connection so they combine.

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