An above-ground swimming pool give your family an inexpensive and easy way to cool off in the summer heat. However, if the ground under your pool is more than 1 inch higher on one side than the opposite side, water could slosh out of the pool, and the pool walls could weaken and become prone to collapse, which might cause serious injury. Thus, you'll need to ensure that the ground is level and compacted before you install the pool. Note: the ground gets leveled before the pool gets erected. Once that happens and the pool is full of water, you can no longer level the ground.
Inspect your yard, and choose the flattest area you possibly can. Sites that have a lot of bumps will require much more work to level. Make sure the site you choose is a foot or two larger than your pool in every direction.
Remove grass, weeds and rocks from the site using a shovel, sod cutter and rake. Alternatively, use a rototiller to remove grass. If you have a few months to spare before the installation of your pool is scheduled to take place, you could lay dark plastic sheets over the area the pool will occupy to slowly kill the grass with little effort.
Attach a level to a long board. Lay the board on the site to see how close to level it is. Alternatively, for a round swimming pool, pound a stake into the center of the site; then use a string and a level to make sure the ground is level.
Dig out any high spots in the site. If the ground is not close to level, it's best to remove dirt to make a level area (as opposed to adding it). That way, the soil under the pool will be firm and solid.
Dump sand onto the site once it is level. Many garden and landscaping supply companies will deliver sand by the truckload. A 2- to 6-inch layer of sand is recommended.
Use a rake to spread the sand over the site evenly.
Compact the sand using a lawn roller, which you can rent from a home and garden center. Then check that the area is level by using your board and level.
Place a tarp or swimming pool protector over the sand. Perform a final check to make sure the area is level. Alternatively, you can purchase a specialized pool pad, made of foam or other materials, which is designed to protect your pool.