A natural swimming pool uses plants and biofilters instead of chlorine; build one by combining a lined swim zone with a planted regeneration area.
What A Natural Swimming Pool Is
A natural swimming pool is a lined basin where clear water is kept clean by plants, helpful bacteria, and mechanical filtration instead of chlorine or bromine. Water moves through shallow planted zones and filter media, where nutrients and particles are trapped and broken down.
Most designs split the water into two main areas. The swimming zone is deep, clear, and easy to enter. The planted regeneration zone is shallow and filled with gravel, pumps, and aquatic plants that act as a living filter. Long running projects in Europe that follow technical guidelines for natural pools use this layout to keep water clear and pleasant for swimmers.
| Aspect | Natural Swimming Pool | Chlorinated Pool |
|---|---|---|
| Water Treatment | Plants, biofilters, circulation pump | Chlorine or other chemical disinfectants |
| Water Feel | Soft, lake like, no chemical smell | Can cause dry skin and sharp odor |
| Visual Style | Stone edges and planted margins | More formal tiles and sharp corners |
| Upfront Cost | Higher due to extra area and planting | Lower for a simple rectangular shell |
| Running Costs | Pumps and plant care, fewer chemicals | Regular chemical top ups and testing |
| Wildlife | Can attract insects, frogs, birds | Less friendly to wildlife |
| Maintenance Style | Skimming, plant trimming, pump care | Vacuuming, scrubbing, chemical balance |
Planning Rules For How To Build A Natural Swimming Pool
Before you mark out a shape in the lawn, check rules, permits, and soil. Many local authorities treat natural pools like any other backyard pool, so you may need a permit, safety barrier, and fence. Before you attempt how to build a natural swimming pool on your own, decide which jobs you can handle and which need a specialist. Some regions base their pool rules on the Centers for Disease Control and Prevention’s Model Aquatic Health Code, so expect clear limits on depth, steps, and rescue gear.
Regulation for natural pools is still evolving. In parts of Europe, projects often follow a formal guideline for private natural swimming pools that sets hygiene and design targets for biological treatment zones. That kind of document is a useful benchmark even if you build outside Europe, because it describes layouts, clear water targets, and plant zones that work in practice.
After you speak with your local building office, check practical site points. You need a sunny spot for plant growth, power for pumps, and access for excavation equipment. Heavy clay can help hold a shape but still needs a liner. Sandy or unstable soil may need extra structure or a concrete shell, so speak with an engineer if the site looks marginal.
Sizing The Swimming And Regeneration Zones
Natural pool builders usually size the planted zone to match or exceed the swimming area. A one to one ratio works in many gardens, while two to one suits warmer regions or heavy use. Studies on natural swimming pools link generous plant zones and good circulation with low nutrients and less algae growth.
Depth also matters. Many private pools use a shallow beach or step area, a mid depth zone for play, and a deeper pocket around two to two and a half meters for strong swimmers or a jumping rock. The planted shelves stay shallow, often between twenty and sixty centimeters deep, which gives roots plenty of light while keeping most stems above water.
Design Choices When Building A Natural Swimming Pool
The hidden structure of the pool matters as much as the plants. Most natural pools use either a reinforced concrete shell, block walls with render, or prefabricated panels, all lined with a quality membrane. The liner needs a soft underlay and careful detailing at steps, walls, and corners so it does not pinch or tear.
Water moves thanks to skimmers, bottom drains, and low energy pumps. The swimming zone sends water to a pump chamber, then through gravel beds, external biofilters, or both, before it returns through the plant zone. The aim is to move the full water volume several times per day without noisy equipment on show, and to keep pipework placed where winter frost or ground movement will not damage it.
Step By Step Build Process
1. Mark Out And Excavate
Set out the outline with stakes and string, then spray a clear line on the grass. Walk around the shape from several angles to check proportions. When you are happy, excavation can start. A digger shapes the main bowl, shelves for plants, and trenches for pipes. Keep topsoil aside for later planting around the pool.
2. Shape Shelves And Base
Ask the digger operator to smooth and compact the base and shelves. Built in benches, a sloping beach, or a dedicated children’s area can be carved at this stage. Once levels are right, add a layer of soft sand or fine screenings under the underlay to protect the liner.
3. Install Liner And Structural Walls
Roll out the geotextile underlay, then lay the liner in the main bowl with generous slack so it can settle without stretching. Fold corners neatly and anchor the edges in a trench or under coping stones. Where you plan masonry walls, concrete steps, or a diving rock, place the liner behind those elements and protect it with extra fabric.
4. Add Plumbing And Pump Hardware
Install skimmers, drains, return inlets, and conduits for pump cables. All penetrations through the liner need proper flanges and seals. Run pipework to a small technical zone that can be hidden behind planting or a timber screen. Many natural pool specialists prefer multiple small pumps instead of one large unit, which gives redundancy and quieter running.
5. Build Regeneration Beds
In the regeneration area, create planting beds with retaining edges, then fill them with graded gravel. Coarse stone sits at the bottom for drainage, topped with finer gravel where roots will spread. External biofilters can be added in series if you expect heavy bather load or long, hot summers.
6. Fill, Plant, And Start The System
Once hard construction is complete, start filling the pool. As the water rises, smooth out any last wrinkles in the liner and double check all fittings for drips. When the planted shelves are flooded to their design depth, place aquatic plants in baskets or directly into the gravel. Switch on the pumps and let the system run continuously so bacteria can colonise the filter media.
Planting And Biological Filtration
Plant choice shapes both the look and the performance of the pool. Many builders follow lists drawn from long running natural pool projects, where emergent plants such as iris, pickerel weed, and cattails share space with submerged oxygenators. Research on natural swimming pools suggests that a mix of species, heights, and root depths helps keep nutrients under control and limits algal blooms.
Divide planting into zones that match water depth. Shallow margins suit moisture loving perennials and grasses, while shelves a little deeper suit basket planted reeds. Submerged plants sit in the deeper parts of the regeneration zone, where they add oxygen and offer habitat for small aquatic creatures that graze on algae.
Water Quality, Safety, And Legal Checks
A natural swimming pool still needs steady water care. Studies on natural swimming ponds show that clear, low nutrient water depends on balanced plant zones, steady circulation, and regular removal of debris. Technical standards for natural pools and local pool codes often set targets for clarity, bacteria levels, and inspection routines.
Public health agencies use tools such as the CDC’s Model Aquatic Health Code to shape rules for public pools, and private owners can borrow ideas from that material. Even if your natural pool does not fall under formal inspection, you can copy the habits: test water periodically, log readings, and react early if clarity or smell starts to change.
Safety details matter from day one. Provide secure fencing, self closing gates, and alarms where local law requires them. Use clear depth markers and keep the deepest area away from steps used by children or older swimmers. Keep rescue gear such as a reaching pole and ring buoy close to the water, and make sure paths and decks drain well so surfaces stay grippy.
Ongoing Care For A Natural Swimming Pool
Once the system has matured, day to day care feels closer to looking after a garden pond than a conventional pool. Skim leaves from the surface, brush steps and walls before they grow slick, and empty skimmer baskets. Check pump strainers and listen for changes in noise that might hint at a blockage.
Plants need seasonal attention. In spring, divide clumps that have spread too far. During warm months, thin excess growth so light still reaches the water. At the end of the season, cut back brown stems to stop dead plant matter breaking down in the pool.
| Time | Maintenance Task | Purpose |
|---|---|---|
| Weekly | Skim leaves and check skimmers | Reduce organic load and keep flows clear |
| Monthly | Brush walls and steps, rinse pump strainers | Limit slime build up and preserve pump life |
| Spring | Divide plants, top up gravel, check liner edges | Restore plant balance and protect the shell |
| Summer | Thin plant growth, monitor clarity and odour | Keep the swim zone open and water inviting |
| Autumn | Net falling leaves, prune dying foliage | Limit nutrient spikes before winter |
| Winter | Remove pumps if needed, protect pipework | Prevent frost damage to equipment |
| After Storms | Clear debris, confirm pumps restart | Keep circulation steady and water clear |
Planning how to build a natural swimming pool takes patience, but the reward is a clear, living pool that fits your garden and swimming habits. Once permits, structure, and planting are in place, the system can give many seasons of chemical free swimming. Small daily habits keep the water clear longer.