You have sited your pond, calculated measurements and dug a hole. Now comes the hard part, what type of liner do you use?
There are many types of liners available varying in materials, color and of course price. As with many things in life, it is a good idea to get the best quality for your budget as the product will last longer and cause fewer headaches down the road. Liners made of Butyl rubber and PVC or low-density polyethylenes are used in better quality liners. These are available in different thicknesses and some even have a Glad bag type web design to offer added strength. Different colors and liners with pebbles glued to the edges for a natural look is an aesthetically pleasing option for some butyl and PVC liners available on the market. But you’re not done yet. Adding an underlay (a cushioning material to go between liner and earth) is a wise decision to get your pond off to a good start and protect it from punctures and the elements. Purchasing a specific underlay material is not entirely necessary however. Sand and even old carpet scraps can be used with basically the same results.
While the aforementioned liners will get the job done for most pond enthusiasts, there are others to choose from. Polythene liners are cheaper but should be avoided if possible. Lacking pliability and prone to becoming brittle and cracking due to sun exposure, polythene is a cheaper option best used only for temporary projects. Geotextiles or “clay-impregnated” liners are on the other end of the spectrum as far as quality and price. Infused with clay, these liners are able to plug small holes and thus sustain minor punctures. While the idea of never having to deal with leaks is a pleasing thought, geotextiles are ideal for larger, wildlife ponds and aren’t necessary for smaller, backyard ponds.
Now that you’ve decided what type of liner is best for your project, you are ready to shop! Remember to add a couple of inches to each dimension before cutting your liner and underlay. It is far better to be left with an overlap than to run out after all your hard work.