Building a water garden using a flexible pond liner gives you the ability to create a pond in any shape and size you like. In order to accurately measure for the liner before you buy it, dig the pond first to avoid incorrect measurements. You'll save yourself extra trips to the garden center for more liner or save yourself some cash on less liner to go toward plants and fish for your finished water garden.
Taking Accurate Measurements
Plan out your garden pond and dig it before you measure for the pond liner. This will include choosing its location; marking its size and placement with a flexible material such as rope or a hose, or spray painting a line; and then digging it out. Finish off the pond by leveling the shelves in it where you will place water plants, and build any additional water features such as waterfalls and streams.
Measure the length between the longest points of the pond. Measure the width between the widest points of the pond. Measure the deepest part of the pond by placing the plank over the area you want to measure, then measure from the bottom of the pond up to the bottom of the plank. Measure any additional water features the same way.
Calculate the total liner length and width by multiplying the depth by two. Add 18 inches (46 cm) to the total depth for overlap at the edges. Add the new total depth to the length and to the width. The new length and width measurements are the final measurements for the size of your pond liner. You can calculate liner size for additional water features the same way.