Seeking advice on plumbing rainwater tanks

Hi all,

I'm planning on installing a 10,000 gallon rainwater harvesting system that will consist of 4 2500 gallon tanks piped in parallel with each other (arranged in a 2x2 grid). The tanks will sit on a 4" pad of gravel topped with 2" of compacted, decomposed granite. This should be fairly stable, but was wondering if I should still make connections to the tanks with something flexible. Thoughts?

Chris

 

All of my tanks say warranty void if not flex line plumbed for the first few feet. They DO settle.