Sagging fresh water tank

[Western Traveler]

Today I pressed my fresh water tank to check the added hitch weight it would create. When I slid under the TT to open the drain I noticed the tank had a roundish shape extending below the fastened points on the Coroplast. I pushed up on it from below to verify it was the tank and not trapped water. The thing is it wasn't an even bulge like one might expect but lower on the right side like a pear. The coroplast is fastened just outside the black iron LP gas pipe, to the frame and I didn't have the time to remove it today. I think I would have noticed this during the PDI. The tank was full then and I crawled the entire bottom.

I would have expected a solid foundation under it. Are these just held in place with straps? Curious what I can expect when I drop the coroplast or is this normal? Could I have a failed baffle or something?

[JRTJH]

There are usually two, three or four 1/16" steel straps about 2.5" wide that are attached to the frame runners under the tank. These straps are all that hold the tanks in position. There is "sometimes" (depending on the type of "polar pack") some insulation under these straps and then the coroplast is installed.

The tanks are made of a flexible plastic that holds its shape, but with the added weight of water, will bulge on the sides and droop on the bottom. If the tank is not leaking and the straps are secure, it's probably OK. I'd start a list of "things for the dealer", put it on the list and the next time you take it in for warranty work, have the dealer check it out to be sure.

[BulletOwner1]

As John said, my Bullet's tank is supported by two steel straps but also one end of the tank sits on the frame rail. It does bulge when full. I'm not real comfortable when looking at it but so far no problems. I have started traveling with less than a full tank.

[Western Traveler]

John and Bullet owner, Thanks for the response.

Traveling with a nearly empty tank is my preference, just enough to use the facilities and for emergencies. I just wanted to see the effect for those times I will fill before heading to a dry camp at the last available water source.

Maybe a portion is sitting on something stouter on one side. I would have expected the bulges to be more uniform on each side of the straps. That is what raised my suspicions.
Good idea to wait for a visit to a service center for now but without jinxing things this is the only thing we have found so far to address and I hope that continues.
The trailer with slide in the closed position passed the gully washer test for days last week.
Wish I had thought of extending the slide to check that too.
Our next trip got delayed a week so more prep time for me. Next up Grand Canyon and Sedona.