Imagine a swimming pool that doesn’t smell like chlorine. One that feels more like a serene, natural pond, alive with the gentle hum of nature. That’s the magic of a natural swimming pool, or a biopool. It’s not just a body of water; it’s a living, breathing ecosystem right in your backyard. Honestly, it’s a game-changer for how we think about our outdoor spaces.
What Exactly Is a Natural Swimming Pool?
At its heart, a natural swimming pool (NSP) or biopool uses Mother Nature’s own filtration system—plants and beneficial microorganisms—to keep the water crystal clear and hygienic. It completely ditches harsh chemicals like chlorine and algaecides. Instead, it relies on a balanced dance between a dedicated swimming zone and a specially designed regeneration zone, which is basically a beautiful water garden.
Here’s the deal: the two main design philosophies are the separate zone system and the combined system. The separate system, the most common, has a distinct area for swimming and another adjacent area for plants and filtration. The combined system mixes them together for a more lagoon-like feel, where you swim amongst the reeds and lilies. Both are stunning, but the separate system tends to be the go-to for a more traditional “pool” experience.
The Nuts and Bolts: How a Biopool Actually Works
It seems almost mystical, right? Clear, clean water without a single chemical. But the science behind it is actually pretty straightforward. It’s all about replicating the self-cleaning processes found in natural bodies of water.
The Regeneration Zone: The Pool’s Lifeblood
This is the star of the show. This planted area is far more than just pretty landscaping; it’s the pool’s biological filter. A pump gently circulates the water from the swimming area into this zone, which is typically filled with a substrate like gravel or clay and packed with specific aquatic plants.
These plants—reeds, rushes, water lilies, and more—are powerhouses. Their root systems provide a massive surface area for beneficial bacteria to colonize. These tiny microbes are the real workhorses, breaking down organic contaminants like bacteria, algae spores, and nutrients from leaves or sunscreen. The plants then absorb these broken-down nutrients, effectively starving out any potential algae. It’s a perfect, closed-loop system.
Circulation and Aeration
Water can’t just sit stagnant. A slow-moving pump (often solar-powered, which is a fantastic modern touch) keeps the water moving. This ensures every drop passes through the regeneration zone multiple times a day. Aeration, sometimes through a small waterfall or fountain, adds precious oxygen to the water, which supercharges the bacterial activity and keeps everything fresh. The sound of trickling water is a beautiful bonus.
Designing Your Natural Oasis: Key Concepts to Consider
Okay, so you’re sold on the idea. But what does it actually take to design one? Well, it’s part art, part ecology. Here are the core biopool design concepts you need to think about.
1. The Size and Ratio is Everything
This is the golden rule. For the system to work effectively, the regeneration zone needs to be large enough to handle the biological load of the swimming zone. A general rule of thumb is a 50/50 split. That is, the plant-filled regeneration area should be at least half the size of the swimming area. For larger pools, you can sometimes get away with a 1:3 ratio (regeneration:swimming), but bigger is always better for the biofilter. Don’t try to skimp here—it’s the foundation of the whole operation.
2. Material Choices: Going Natural
Forget classic pool plaster. Natural pools embrace materials that blend into the landscape and support biological life. Common choices include:
- EPDM Rubber Liners: Flexible, durable, and safe for aquatic life.
- Clay or Bentonite: A completely natural sealant that creates a pond-like base.
- Reinforced Concrete: Often used for the swimming area and then covered with a liner or finish for a more natural look.
The edges are usually softened with stone, gravel, or even timber, encouraging planting that merges the pool seamlessly with the rest of the garden.
3. Plant Selection: The Right Greens for Clean
You can’t just throw any old plant in the water. A successful design uses a mix of emergent, floating, and submerged plants, each with a job to do.
| Plant Type | Role | Examples |
| Emergent / Marginal | Primary filtration. Their roots host the most bacteria. | Cattails, Reeds, Rushes, Irises |
| Floating | Provide shade, reducing algae growth. Their roots also filter. | Water Lilies, Water Lettuce |
| Submerged (Oxygenators) | Release oxygen into the water, benefiting bacteria. | Hornwort, Water Crowfoot |
The Real Deal: Benefits vs. Considerations
Let’s be real, no system is perfect. Here’s a honest look at what you’re signing up for.
The Glorious Upsides
Why are people so passionate about these pools? The benefits are pretty compelling.
- Chemical-Free: No more red eyes, bleached swimsuits, or dry, itchy skin. The water is soft and gentle.
- Eco-Friendly: They have a much lower carbon footprint once established. They use less energy (if designed well) and support local biodiversity, attracting dragonflies, frogs, and birds.
- Year-Round Beauty: Honestly, they’re a landscape feature even when it’s too cold to swim. The regeneration zone becomes a stunning frost-kissed garden in winter.
- Lower Long-Term Costs: After the initial investment, you’re not buying chemicals every month. Your main costs are a bit of electricity for the pump.
The Things to Keep in Mind
It’s not all sunshine and roses—well, it is, but you know what I mean.
- Higher Initial Cost: The design and construction are complex. You’re often looking at a higher upfront cost compared to a traditional pool.
- Space Requirements: That crucial 50/50 ratio means you need a significant amount of land.
- Patience is a Virtue: The pool needs time to “mature.” It can take a few weeks for the biological balance to establish itself when you first fill it or at the start of each season.
- It’s a Garden: It requires gardening maintenance—pruning plants, maybe cleaning out a bit of sediment. It’s a different kind of upkeep than tossing in a chlorine tablet.
Is a Natural Swimming Pool Right For You?
So, who’s the ideal candidate for a biopool? If you’re an avid gardener, an eco-enthusiast, or someone who dreams of a backyard that feels like a private nature reserve, then this is absolutely for you. If you prefer the sterile, bright-blue, maintenance-light experience of a traditional pool, you might find the natural approach a bit too… well, natural.
The trend is moving towards these sustainable oases. People are craving a deeper connection to nature, even in their own backyards. A natural swimming pool isn’t just a place to swim laps; it’s a statement. A commitment to living a little more gently on the planet. And it offers a slice of wilderness, a tranquil escape that changes with the seasons, right outside your door. It makes you think: why have just a pool when you can have an ecosystem?