Once the hole is completed, it is time to prepare it for filling with water. Check the sides and bottom to be sure that all roots and stones are removed. The sides must be as smooth as possible to prevent anything from protruding and punching a hole in the liner.

Liner Installation - Installing the pond liner is a two person job. If it is a sunny day, let the liner set in the sun for a few hours to make it more flexible. Make sure that it overlaps the sides of the pond evenly before you start adding any water. Once the water begins to flow, it is very difficult to make any adjustments.

Once you start to add water, be ready to move around the liner and fold the corners and uneven areas together neatly as the pond fills. The weight of the water will prevent you from making changes to the folds later so be sure to do it as the water is filling the pond.

When the pond is filled and the liner has settled into place, you may trim off the excess liner at the edges. Be sure to leave a little excess to allow for expansion and contraction during hot and cold weather. 

Adding Water - If you use a municipal water supply and are going to introduce fish into your pond, let the water set for a few days to allow the chlorine to dissipate into the air. Or, you can use one of the commercial preparations that will dispel the chlorine quickly. 

Remember that fish and chlorine do not mix.

Some people recommend inoculating the pond with a gallon of water taken from an existing pond. The theory is that this will get your pond off to a quicker start in establishing a population of micro-organisms. In fact, whether you do this or not, the bacteria and other organisms will quickly find your pond.