Pond Liner Sizing
Measure from a Plan
Length of liner required = Max. length of Pond + (2 x max. depth of pond) + min. 2 feet (min. 60 cm) overlap
Width of liner required = Max. width of pond + (2 x max. depth of pond) + min. 2 feet (min. 60 cm) overlap
Measure off a Completed Excavation
If you are measuring off a completed excavation, use a flexible measuring tape or a rope that completely conforms to the contours of the excavation.
To determine the full length of liner required, run the tape or rope down into the pond, exactly following the contours of the excavation, across all the ledges, to the bottom of the pond, and back out the other side.
Then add at least 2 feet or 60 cm (minimum 1 foot or 30 cm per side) to allow for sufficient liner overlap outside of the pond.
Use the same method to determine the width of the liner.
Be sure to measure across the maximum length and width and at right angles to each other.
Using one of the above formulas and including a minimum liner overlap of 2 feet (60 cm) for both length and width, you determine a required liner size of 19' x 23'.
Now all you have to do is select from either Firestone or Carlisle and look for a suitable size. In this case, the only suitable liner size is 20' x 25'.