There are as many reasons for building a natural pond and there are designs and options for customization. One of the most popular reasons to build a backyard pond is to expand your options for swimming. Putting in a pool doesn’t just come with a high cost for excavation and pouring concrete, but it also leads to high ongoing costs for materials like chlorine and filter replacements. Adding a pond to your property with the express purpose of swimming also improves the value of your property and introduces natural beauty. But a pond you’re designing for swimming purposes will need a few extra elements that are optional for other types of water features.
First, you’ll want to make sure you’re using a flexible pond liner in the swimming pond rather than relying on a bentonite clay treatment or the soil’s natural ability to hold water. Even ponds dug into soils with a high clay content will lose a lot of water to seepage over time. Seepage can leave you refilling your pond every few months as water slowly escapes through spaces between the particles of soil. Applying bentonite clay is another option, but since 10 to 12 inches of the material must cover the entire pond for a tight seal, it’s more expensive than you might expect. A pond liner, like the multi-layered RPE product from BTL Liners, is a much better choice since it’s practically impermeable, easy to install, and won’t slowly fail over time like natural sealing methods. Even if you can find bentonite for a cheaper price than a flexible pond liner, keep in mind that it must be refreshed or replaced every five to ten years. Most liners from BTL can last for 20 years or more.
You’ll also want a thicker or more durable liner than you might use in a pond that won’t have foot traffic. Ponds that are only for fish or plants don’t have people jumping in them and splashing around, so the liner doesn’t have to handle as much wear and tear. Just moving up to a thicker number of mils isn’t your only option. A better option is to choose a reinforced material like multi-layered RPE. This material is thin and flexible, making it easy to install, but it’s also tough enough to resist tearing during heavy swimming use. Make sure you clear away as many rocks, roots, and other debris with puncture risks before applying the liner; regardless of the material you choose.
Natural swimming ponds can have water nearly as clear as a traditional pool, but only with some kind of natural filtration system. The two main options used for swimming ponds are gravel filter beds and planted restoration zones. Gravel filter beds trap a lot of sediment and process water relatively quickly, but they also require buried pipes and at least one powered pump. Planted beds are more popular because there is no need for a pump and a combination of different water plants are used to clean the water without electricity or much work on your behalf. However, planted beds tend to take up more space than gravel filters, requiring as much volume and size as the swimming area.
Finally, you’ll also want to reinforce the banks or edges of the pond. If you plan to enter from any part of the bank, make sure the entire edge is lined with rock or a thick layer of sand. This keeps the liner from shifting, preventing partial bank collapse and flooding around the pond. Setting up specific entry and exit points, like the stairs on a traditional pool, can reduce the amount of work necessary to reinforce the entire bank. This also frees you up to pursue different aesthetic styles and planted banks that couldn’t handle your normal swimming foot traffic.
