Natural Swimming Pools & Ponds

Landscape design, Nature, and recreation all meet in this stunning and fun eco-alternative.

By Christopher Robin Paquette
From the April 2024 Issue


Natural swimming pools are a growing trend in the U.S., and for good reason. They offer a number of advantages over traditional chlorine pools, including being more environmentally friendly, easier to maintain, and more aesthetically pleasing. If clients are looking for a more natural and sustainable way to enjoy swimming, a natural swimming pool (NSP) is a great option.

Natural Swimming Pools & Ponds
The Garden Swim Ponds created by Robin’s Nest have pool edges lined by filtering plants. They are a chemical-free and more naturalistic alternative to traditional pools. (Photo: Robin’s Nest)

NSP Basics

A NSP is a pool that uses plants, oxygen, and bacteria to clean the water instead of chemicals. The traditional NSP, developed in Europe more than 30 years ago, typically uses a swim zone wall to separate the swim area from the plants/bio-filter area.

As with any new popular product, companies develop their own techniques to accomplish the end result. Our technique, in development for 18+ years, is the Garden Swim Pond, or GSP. Unlike the traditional NSP, there is no swim zone wall. Instead, the pool edges are lined by filtering plants, with the rest of the filtering plants located in a side area, using a waterfall return to the main swimming area.

Natural Swimming Pools & Ponds
(Photo: Robin’s Nest)

Think of it this way: the area around the perimeter of the GSP is akin to a large hydroponics plant growing system where the pool water is drawn through a soilless medium (crushed stone), trapping nutrients (organic matter) in its bed, feeding water plants which use their root systems to consume nutrients, thus cleaning and filtering the water. All this while adding natural beauty, balance, and fragrance to a swimming experience and natural habitat to the backyard.

We’ve been building NSPs for 28+ years, so we know our ideal client. Many are retired and want grandkids to visit and play in the pool. Our other client profile is the young couple with kids who want a chlorine-free environment to swim in. Winter skating (yes, you can skate on a NSP!) is also an interest. The third profile is the water dog owner. We built our first NSP, unbeknownst to us, for a dog loving couple with no kids! But all these clients often love gardening — which is why there are opportunities for landscape pros in this business. We’ve had virtually no one in the traditional pool business approach us about NSPs. It’s almost always a landscape contractor or stone mason.

Natural Swimming Pool
A natural swim pool uses a swim zone wall to separate the swim area from the plants/bio-filter area.
garden swim pond
A garden swim pond is more naturalistic. (Photos: Robin’s Nest)

Benefits & Drawbacks

There are many benefits to NSPs. Here are just a few:

  • They are more environmentally friendly. As mentioned, natural swimming pools do not use chemicals.
  • They are easier to maintain. NSPs do not require the same level of maintenance as traditional chlorine pools. Clients will not need to add chemicals and will not need to vacuum the pool as often.
  • They are more aesthetically pleasing. NSPs can be designed to look like a natural pond or lake. This makes them a much more attractive addition to a backyard.
  • They create natural habitats. NSPs offer local wildlife an oasis to drink, bathe, and live. Birds, reptiles, and amphibians are just a few of the critters that may appear. The plants in a NSP support dragonflies, damselflies, and other beneficial insects. Bees need water and are our best pollinators. Water increases the odds of a successful backyard ecological habitat.
  • They are energy efficient. Unlike conventional pools that use one oversized pump with some sort of mechanical sand or cartridge filter, our system uses a very energy efficient variable speed drive pump. This allows us to run the filters (planted areas) as well as added on brooks, streams, waterfalls and or fountains, without additional pumps.
  • They utilize rainfall. Another great feature of a NSP is the ability to use it to irrigate your lawn and/or gardens, without using any tap water. Additionally, by running downspout water from your roof, through a pre-filter, to the pond, you can keep your pond’s water level topped off without adding any potable water! This feature not only will save money, but conserves water.
A natural swim pond. (Photo: Robin’s Nest)


However, NSPs have several drawbacks. Keep in mind:

  • Installation costs can be more expensive. NSPs are typically more costly to install than traditional chlorine pools because they require more specialized equipment and materials.
  • They may not be suitable for all climates. This includes some warmer climates where dangerous water borne bugs live.
  • They may require more maintenance than counted on. While NSPs don’t require the same level of maintenance as traditional chlorine pools, the plants will need to be trimmed and debris removed from the pool on a regular basis. If located in a freezing environment, much like a regular pool, it will have to be winterized.

Common Misconceptions

As a relatively new concept within the U.S., there are many myths about NSPs. Here’s the reality.

  • They are natural. While they are designed to mimic nature, they require man made materials, most of which should last many years. While a lot of plastics are used in their construction, compared to concrete materials, chemical consumption, and lack of habitat with regular pools, it seems to still be a “win” for the environment. Air or water pumps are also usually required, which consumes electricity.
  • They require water changes. No, a well-balanced pond should never need water changes — not even to clean them. If an NSP needs a water change, the owner has let the pool get out of balance.
  • “I use a saltwater system for my NSP, so I’m not using chlorine.” A “saltwater pool” is not an alternative to chlorine; it’s a different way of generating chlorine. It uses salt to create chlorine. Using it on a rubber liner will likely negate the warranty and shorten its lifespan. And you can imagine what happens to filter plants exposed to salt.
  • The water needs to be turned over every hour. We’ve found turning it over four to six times a day works well, depending on its activity. This is concerning bio-filter flow, not decorative waterfalls, etc. Slow is best when using up-flow through aggregate in a bio-filter. Both our bio-filter and our perimeter filter, which goes completely around our GSPs use up-flow filtration.
  • NSPs and GSPs need a continuous water source. No, they do not. As mentioned, these pools do not want a lot of water changes, or new water to contend with their balance. Once filled, they are a closed vessel, or body of water. The goal is to always have balanced water that doesn’t have to contend with large inputs of new minerals, which is what comes with new water. Knowing what’s in a client’s tap water allows us to mitigate almost any issue before it goes into a pool.
  • Permits aren’t needed, it’s a pond. No, it’s a pool in the eyes of more code offices, as it should be. People are swimming in it, so I assume you want to construct it for safety. There are national codes for swimming pools. These should be followed. Fencing, slopes, electrical grounding, egress, drains, etc., are important even in ponds. Always ask your codes office what is required and do the proper permits.

Construction: Plants, Liners, & The Rock Debate

As mentioned, we use the GSP technique. We developed these methods to be economical, functional, and simple for the client to care for. It also conveys a larger, more natural pond look, that doesn’t appear to be manmade in any way without up close inspection. Aesthetically, our GSP system melds into the habitat.

Water lilies are typically used in a swim pond to create a shelf or well in the filter zones, or on the sidewall of the swim zone. (Photo: Robin’s Nest)

Plants used to filter the pool/pond are specific to the plant hardiness zone. Many overlap or are treated as annuals. We like to use natives as much as possible. Most are bog or marginal area plants, or shallow water thriving plants. Iris, marsh marigold, rushes, horsetail, lobelia cardinalis, and sweet flag are many of the varieties we use. When it comes to aquatic plants, it’s interesting to see the overlap in hardiness zones. On the lower end of depth, water lilies, which like 24″ to 36″ depths, are typically used by way of creating a shelf or well in the filter zones or on the sidewall of the swim zone.

Additionally, by using a rubber membrane, our system allows for total flexibility in the pool shape and design. Many designs use concrete, gunite, or fiberglass for water containment. We don’t subscribe to most of these newer techniques, as they are an environmental burden, and, in New England and many other areas of the U.S. they crack at some point, leading to expensive repair costs.

We use a standard 50′ x 100′ epdm rubber liner. GSPs can be as large as 60’ x 35′ in size, with an 8′ depth in one half. A long-standing argument is to cover or not cover the swim area liner with rock? With traditional NSPs that use epdm rubber liner to hold water, they don’t cover their liner with stone in the swimming area, as a rule. Yet many new companies building NPSs claim you should cover your liner with stone. After 28 years of building water features with bio-filtration, it’s apparent, for many reasons, why covering your whole liner is not a good idea.

Typical damage to liners occurs when large stones are set on them during the construction process. On one project, a high-end architectural design build firm, we stopped counting the holes we found in the liner at 259! The cause? The point of a shovel used to dislodge a strap. A $30,000 expense for not paying attention to detail!

Another reason regards finding a leak. If you cover your liner with 1-2 ton boulders, sprinkle in some 2″ stone, maybe even some 3⁄4″, then need to find and repair a leak in the bottom or sides of your pool, how will it go? A leak can be caused by poor installation, plant roots, substrate shifting, etc. It’s a horrible thought you should avoid at all costs.

A final reason for avoiding rocks is the liner becomes harder to clean. Our company, having been in business for 28+ years, has tried the quick “stone it all in” installation technique. We’ve also serviced our customers for 28+ years and have experienced cleaning stone-filled bodies of water. It’s a nightmare, and very costly. I’m all for profits, but not ones caused by shortcuts we take.

natural swimming pool
Swimmers enjoy a natural swim pool. (Photo: Robin’s Nest)


All of these pools, including our GSPs, also develop a bio-film on almost all surfaces. This film is slippery. They also can harbor debris in cracks and joints between boulders, and other stones. This can lead to anaerobic bacteria in places you can’t clean without a total pump-out, if that even works. This can cause a major setback for the water quality, as the water takes time to come into balance, and you’ll be starting over if you have to pump out water and add “new” water.

On the other hand, exposed liner is easily cleaned with a brush or, as most clients choose, a robotic vacuum cleaner. Proper shaping of walls and floors also helps to remove debris by directing it to a smaller area that has bottom drains, like many pools. In this way, cleaning care and techniques ensure little loss of water.

What’s the upside to covering the liner with stone? Yes, you can dig a less structural hole for a pool and fill it with rock to hold it together. But the suggestion that this method is quicker, I find to be untrue — especially if it comes with compromised liner integrity.

For some, looking at rock is better than looking at a black mirror. It’s purely aesthetic. On a personal level, I feel the black liner is reflective of its surroundings, making the pool a mirror of sky and landscape. All too often I hear people comment, “I’d never jump in that pool, you can’t see the bottom.” This isn’t true. If you drop a single rock in the pool, it’s going to stand out. The water is crystal clear, all the way to the bottom; the liner is simply black!

NSP & GSP Kits

Robins Nest has developed kits to help contractors and install GSPs and NSPs on their own projects. These kits come with design, instructions, and support. We’ve trained several contractors on the techniques we use, with great success and continued support. Each kit is customized to meet the client’s needs, considering climate, size, and water quality. Our first requirement is a soil analysis, then a test of the water to be used to refill and keep the GPS topped off.

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Unlike some designs, you should never have to pump out a NSP/ GSP to clean it. This is a waste of water and means balancing efforts need to be started all over again. Our system uses top of the line skimmers that do not overload plant-filters with debris. Simply put, a little prevention allows for easily maintained water quality. This can add service dollars to your bottom line.

As part of the installation, you can purchase aquatic plants from us, local nurseries, or best yet, your own nursery. We’ll help you develop simple plant care and growing methods for your customers’ pools and other retail buyers. We also have a few products for water quality and plant care you may choose to stock and sell. These are also geared towards water gardens as well as your NSP/GSP sales. Whatever the need, we will support your growth in this industry.

My company puts top priority on customer care. It’s the cornerstone to success in this business since no one wants to look at dirty, algae covered water. Our goals have always been clean water, safety, longevity, and above all else, serviceability. Simple design, care, and support are of utmost importance. Of course, the artistic drive dictates our installations be beautiful and awe inspiring, as well. It’s how we maintain customer satisfaction and learn. It’s a product of our clients’ desire for something that emulates a swimming hole out in Nature, with room for jumping rocks, rope swings, and docks.

Robin’s Nest, LLCPaquette is the owner and founder of Robin’s Nest, LLC, based in Buxton, ME, where he’s been building plant-filtered water features for over 30 years. He has spoken to thousands of gardeners over the years about water features and given countless workshops on construction of water gardens and NSP and GSPs. Paquette has also been deeply involved in local farming and his extension service, serving as extension president and Master Gardener president for a number of years, while volunteering as a Master Gardener, as well. 

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