Once the site has been selected, using marking paint, draw an outline of the pond that will collect the water. There are two ways to line the pond. You can either purchase pond liner, which comes flat and can be molded to whatever shape you choose to dig or you can purchase a rigid pond tub. If you choose the latter, you’ll need to outline that exact shape whereas if you use the pond liner, you can create a free form. Outline both where the pond will go as well as the space where the rocks and plants will go surrounding it. If the waterfall is going to be more of a gradual stream rather than a steep drop-off, you’ll want to extend the pond liner up to the waterfall so that the water doesn’t seep into the ground as it moves down the fall.