Q: I’d like to build a pond but my soil doesn’t hold water. What types of liners are there?
Jasper- Colrain, MA
A: If you have a natural- or clay bottom pond that doesn’t hold much – if any – water, a pond liner may be your only leak-proof option. But before we outline the different types of liners you can use, let’s first discuss what’s currently in your pond.
Many ponds will contain some water. If your pond is more than 25 percent full and you want to install a liner, we recommend you either drain the pond before laying the liner or plan to put two feet or more sand or soil on top of the liner once its installed.
If your pond is less than 25 percent full, you have several liner options, which we’ve outlined below.
Two types of liners are used in pond and reservoir applications: poly vinyl chloride (PVC) and reinforced polyethylene (RPE).
- PVC is widely used in irrigation reservoirs, detention ponds and golf course ponds. PVC liner is very flexible and cost effective. When installing this type of liner, we recommend your pond’s slope to be 3:1 for cover soil to stay in place, and we suggest you cover the liner with 12 inches of sand or clean soil to protect it from degrading in the sun.
- RPE is widely used for more durable applications for water activities or in areas that get a lot of wildlife visitors, like agriculture ponds, irrigation reservoirs and golf course ponds. As with the PVC, we suggest you cover the liner with one foot of sand or clean soil where liner could be exposed to sunlight.
Ethylene propylene diene monomer (EPDM) liners are mainly used in small water gardens. The synthetic rubber isn’t durable enough to handle large applications like your half-acre pond. Stick with PVC or RPE instead.
In addition to coming in different material types, liners come in different thicknesses. PVC comes in 20 and 30 millimeter thicknesses; RPE comes in 30, 36 and 45 millimeter thicknesses. The higher the number, the more durable and puncture-resistant the liner.
If you have livestock, deer or other wildlife coming in the pond, you’ll need at least a 30 millimeter RPE liner to withstand those hooves and claws.
Measure Twice, Cut Once
When you’re ready to order your liner, get the measurements of your pond, including its length, width and maximum depth. Plug those numbers into an online calculator, and you’ll find out what size liner you require.
Pond Talk: What are some tips you can share with readers for installing a large pond liner?