Drawing H2O from both tanks and not just one

[TwoDogInn]

We have a new 21G that has two tanks for a total of 100 gallons. I have been suspicious of how fast we draw down from full and how fast we fill up when empty so I did a test. I believe I learned that I am not drawing down from the rear tank. Here is what I did:

After filling up I drained the forward tank via the tank gate valve; I netted almost 10 homer buckets which made sense. I checked the tank level inside and it was on empty. I switched to dry camp mode and turned on water pump, opening a faucet to confirm I was running dry. I then drained about nine homer buckets from the rear tank via the gate valve, demonstrating I had plenty of water left in the trailer.

Both tanks fill from the single connection; is there a trick to make sure both tanks draw down equally? Is there a flaw in my testing?

Thanks

[RoJoSo]

I do not own a 21G, so I'm just thinking out of the box here.

Is it that the pump is drawing from the rear tank and as the rear tank empties then the front tank flows back into the rear tank?
Not sure what your water usage is over a period of time, so just a thought.

Try filling the tanks and draining and measuring from the rear tank first, then see how many gallons you are getting.
If you get the 95 to 100 gallons out of the rear, then this should answer some questions.

Hopefully someone that owns a 21G can give some more information. A call or an email to GD may serve informative.

[huntindog]

We have a new 21G that has two tanks for a total of 100 gallons. I have been suspicious of how fast we draw down from full and how fast we fill up when empty so I did a test. I believe I learned that I am not drawing down from the rear tank. Here is what I did:

After filling up I drained the forward tank via the tank gate valve; I netted almost 10 homer buckets which made sense. I checked the tank level inside and it was on empty. I switched to dry camp mode and turned on water pump, opening a faucet to confirm I was running dry. I then drained about nine homer buckets from the rear tank via the gate valve, demonstrating I had plenty of water left in the trailer.

Both tanks fill from the single connection; is there a trick to make sure both tanks draw down equally? Is there a flaw in my testing?

Thanks

From what I have read, the tanks are connected via a small hose. The water slowly balances between the tanks. In a real camping situation, you will never notice it. Using the 2" tank dump is much faster, so the balancing cannot keep up.

Try this: fill one tank completely, then come back an hour later and see how much more you can put in it.
Never mind, I just saw that you only have one fill. So that will not work for you. I have two tanks and two fills. Other than that, I believe they are configured the same.