Outdoor shower: Positioning
Find a location for the shower. We placed it on a gravel pad to help drainage and also added concrete pavers to stand on.
Dig a 12-inch-deep hole for the center shower pole. Place it so the faucet handle will project outward at 45° between the wing walls.
Set the wing walls at square to each other and attach them to the pole (with three 12-inch screws each) so their legs only go 6 inches into the ground.
Check verticality with a level before tamping and compacting soil.
Full article with tools and materials list