Before excavating the hole for the pond liner of your outdoor water fountain, call the Call Before You Dig phone number, so as to avoid severing any underground lines. And there's a second call you may have to make: namely, to a certified electrician. Do you have a GFCI outlet near where the artificial pond will be? If not, call the electrician and have one installed. How near is "near?" Well, in my case, I was working with a pump with a 6-foot cord -- so the outlet had to be nearer than that. By the way, a great location for a water fountain is near a deck or patio, where you'll be within earshot of its gurgling sound as you kick back and unwind outdoors.
Your first landscaping task is to remove any weeds from the area you've selected for your outdoor water fountain, and make sure it's level. Then you will dig out the hole, into which the preformed plastic pond liner will be placed. To get an accurate measurement for the hole's dimensions, simply flip the preformed pond liner upside down and trace around it. The pond liner that I used is just a small, cheap, rigid liner, 7" deep with a diameter of 2'.
A water feature using a pond liner of this size will be just large enough to make a statement in your landscaping -- if you make it the focal point of a small niche on your landscape. Just use a "big fish in a small pond" approach (pardon the pun). That is, make sure your water fountain is situated in an area of your landscape where it won't be upstaged by larger elements. When you choose plants to grow around your water fountain, make sure their height at maturity is short, relative to the water fountain statuary. Draw the eye to the artificial pond by having a stone path lead up to it, by accenting it with a bright color, or by any one of a number of similar landscape design tricks.
How deep should you make your hole? Well, what's the depth of your liner? Whatever that depth is, dig just a tad deeper. As far as the diameter of the hole is concerned, attempt an exact match with the diameter of the liner, but do not obsess over it. Should the hole end up too wide, you can just plug the gap with sand.
Sand will also be used at the bottom of the hole, since a sand floor will be malleable enough to allow you to play with the height of the pond liner. Put about an inch of sand in, so that the top rim of the preformed pond liner will stand about an inch above ground level -- reducing the amount of dirt that will keep falling into your artificial pond. You'll be pushing the sand around at the bottom of the hole to get the level of the pond liner just right.
Next, place the preformed plastic pond liner into the hole. Check for levelness by placing a carpenter's level across it (see photo above) -- both front to back and left to right. Does the carpenter's level indicate that it's even? No worry. If it's uneven, pull out the pond liner and adjust the sand beneath.
On Page 3 we continue with the project, turning our attention to the water fountain's statuary....