Introduction
Natural pools represent an ecological alternative to conventional pools, using aquatic plants and biological processes to keep water clean and crystal clear. In Margem Sul, where environmental awareness is growing and many property owners seek sustainable solutions, this option is gaining increasing interest.
Unlike traditional pools that depend on chemicals, natural pools create a balanced ecosystem that self-regulates. The result is pure, chlorine-free water, ideal for people with sensitive skin or allergies.
This guide explores the concept of natural pools, their types, maintenance requirements, and specific considerations for the Margem Sul region.
What Are Natural Pools
Basic Concept
| Aspect | Description |
|---|
| Definition | Pool using biological filtration |
| Principle | Aquatic plants filter and purify |
| Chemicals | Zero or minimal |
| Appearance | Integrated into landscape |
| Ecosystem | Balanced and self-sustaining |
Difference from Conventional Pools
| Characteristic | Conventional Pool | Natural Pool |
|---|
| Disinfection | Chlorine/bromine | Biological |
| Appearance | Artificial | Natural |
| Chemical maintenance | Constant | None |
| Energy consumption | High | Low to medium |
| Environmental impact | Significant | Minimal |
| Biodiversity | None | Rich |
| Feel on skin | Can irritate | Soft |
Main Components
| Zone | Function | Proportion |
|---|
| Swimming zone | Bathing area | 50-70% |
| Regeneration zone | Biological filtration | 30-50% |
| Circulation system | Water movement | Low-consumption pumps |
| Substrate | Habitat for bacteria | Gravel, sand |
| Aquatic plants | Absorb nutrients | Various species |
**Important Note**
A well-designed natural pool is not just a pool, it's a complete ecosystem that provides quality bathing while supporting aquatic life and plants.
Types of Natural Pools
Main Categories
| Type | Characteristics | Technology |
|---|
| Type 1 | Fully natural | Plants only, no pump |
| Type 2 | Natural with circulation | Plants + pump |
| Type 3 | Hybrid | Plants + mechanical filtration |
| Type 4 | Assisted biological | Biological filter + optional UV |
| Type 5 | Living Pool | Advanced technology |
Type 1 - Fully Natural
| Aspect | Description |
|---|
| Circulation | Natural only (convection) |
| Filtration | 100% plants |
| Maintenance | Very low |
| Regeneration area | 50% or more |
| Operating cost | Minimal |
| Appearance | Natural pond |
Type 2 - Natural with Circulation
| Aspect | Description |
|---|
| Circulation | Low-consumption pump |
| Filtration | Mainly plants |
| Maintenance | Low |
| Regeneration area | 40-50% |
| Operating cost | Low |
| Appearance | Integrated natural |
Type 3 - Hybrid
| Aspect | Description |
|---|
| Circulation | Conventional pump |
| Filtration | Plants + mechanical filter |
| Maintenance | Moderate |
| Regeneration area | 30-40% |
| Operating cost | Moderate |
| Appearance | Semi-natural |
Types 4 and 5 - Technological
| Aspect | Type 4 | Type 5 |
|---|
| Circulation | Efficient pump | Optimised system |
| Filtration | Biological + UV | Multi-phase |
| Maintenance | Moderate | Low to moderate |
| Regeneration area | 20-30% | 15-25% |
| Appearance | Pool with plants | Modern design |
| Cost | Higher | Premium |
💡 Dica Profissional
For Margem Sul, types 2 and 3 are generally most suitable, balancing naturalness, available space, and ease of maintenance.
Aquatic Plants
Types of Plants
| Category | Function | Examples |
|---|
| Emergent | Nutrient absorption | Typha, Iris, Juncus |
| Submerged | Oxygenation | Elodea, Potamogeton |
| Floating | Shade, absorption | Water lilies, lotus |
| Marginal | Aesthetics, habitat | Carex, Cyperus |
Plants Recommended for Portugal
| Plant | Type | Characteristics |
|---|
| Typha latifolia | Emergent | Very efficient, hardy |
| Iris pseudacorus | Emergent | Yellow flowers, resistant |
| Phragmites australis | Emergent | Excellent filtration |
| Nymphaea alba | Floating | Native water lily |
| Ceratophyllum | Submerged | Efficient oxygenation |
| Myriophyllum | Submerged | Excellent absorption |
Quantity and Distribution
| Zone | Density | Maintenance |
|---|
| Margins | 6-8 plants/m² | Annual pruning |
| Shallow zone | 4-6 plants/m² | Periodic thinning |
| Deep zone | 2-3 plants/m² | Algae control |
| Surface | 30-50% coverage | Excess removal |
Plant Care
| Season | Task |
|---|
| Spring | Planting, division |
| Summer | Growth control |
| Autumn | Dead leaf removal |
| Winter | Pruning, protection |
Construction
Construction Stages
| Phase | Description | Duration |
|---|
| 1. Design | Layout, calculations | 2-4 weeks |
| 2. Excavation | Swimming and regeneration zones | 1-2 weeks |
| 3. Waterproofing | Liner or concrete | 1-2 weeks |
| 4. Hydraulic installation | Pumps, piping | 1 week |
| 5. Substrate | Gravel, sand | 1 week |
| 6. Planting | Aquatic plants | 1-2 weeks |
| 7. Filling | Water and maturation | 4-8 weeks |
Waterproofing Materials
| Material | Advantages | Disadvantages |
|---|
| EPDM | Flexible, durable | Medium cost |
| PVC | Economical | Less durable |
| Reinforced concrete | Very durable | High cost |
| Compacted clay | Natural | Requires expertise |
| Bentonite | Natural, self-repairing | Specific conditions |
Sizing
| Element | Recommendation |
|---|
| Minimum total area | 50-70 m² |
| Swimming depth | 1.5-2.5 m |
| Regeneration depth | 0.3-0.8 m |
| Regeneration ratio | 30-50% of area |
| Minimum volume | 100-150 m³ |
**Important Warning**
An undersized natural pool cannot maintain biological balance. Respect minimum proportions to ensure long-term success.
Maintenance
Regular Maintenance
| Task | Frequency | Description |
|---|
| Debris removal | Weekly | Leaves, insects |
| Pump check | Weekly | Operation |
| Algae control | As needed | Manual removal |
| Plant pruning | Monthly (summer) | Growth control |
| Water testing | Monthly | pH, oxygen |
| Skimmer cleaning | Weekly | Floating debris |
Seasonal Maintenance
| Season | Main Tasks |
|---|
| Spring | System start-up, planting, cleaning |
| Summer | Algae control, pruning, monitoring |
| Autumn | Leaf removal, winter preparation |
| Winter | Equipment protection, minimum operation |
Water Parameters
| Parameter | Ideal Value | Action if Outside |
|---|
| pH | 6.5 - 8.0 | Slow natural adjustment |
| Oxygen | >6 mg/l | Increase circulation |
| Nitrates | <25 mg/l | More plants |
| Phosphates | <0.03 mg/l | Remove algae |
| Transparency | >1.5 m | Check balance |
Algae Control
| Algae Type | Cause | Solution |
|---|
| Filamentous | Excess nutrients | Remove manually, more plants |
| Green water | Phytoplankton | Less light, more competition |
| Wall algae | Nutrients, light | Brush, shading |
Costs
Initial Investment
| Component | Estimated Cost |
|---|
| Excavation and earthworks | €3,000 - €8,000 |
| Waterproofing | €5,000 - €15,000 |
| Hydraulic system | €2,000 - €5,000 |
| Substrate and gravel | €1,500 - €4,000 |
| Aquatic plants | €1,000 - €3,000 |
| Finishing | €2,000 - €8,000 |
| **Total (50-80 m²)** | **€15,000 - €45,000** |
Comparison with Conventional Pool
| Aspect | Conventional | Natural |
|---|
| Construction | €20,000 - €40,000 | €15,000 - €45,000 |
| Annual maintenance | €1,500 - €3,000 | €300 - €800 |
| Annual energy | €800 - €1,500 | €200 - €500 |
| Annual chemicals | €500 - €1,000 | €0 |
| **10-year cost** | **€48,000 - €85,000** | **€20,000 - €58,000** |
Operating Costs
| Item | Annual Cost |
|---|
| Electricity | €150 - €400 |
| Plant replacement | €50 - €200 |
| Equipment maintenance | €100 - €300 |
| Water tests | €50 - €100 |
| Occasional repairs | €100 - €300 |
| **Annual total** | **€450 - €1,300** |
Advantages and Disadvantages
Advantages
| Advantage | Description |
|---|
| Chemical-free | Ideal for sensitive skin |
| Ecological | Low environmental impact |
| Biodiversity | Attracts wildlife |
| Aesthetic | Landscape integration |
| Low operating cost | Long-term savings |
| Property value | Differentiation |
| Wellbeing | Connection with nature |
Disadvantages
| Disadvantage | Consideration |
|---|
| Space required | Larger than conventional |
| Maturation period | Initial 4-8 weeks |
| Non-sterile water | May contain organisms |
| Different maintenance | Requires learning |
| Temperature | Not heated (generally) |
| Fauna | May attract insects |
| Specialisation | Few professionals |
Who It's Suited For
| Suited | Not Suited |
|---|
| Nature lovers | Those preferring sterile water |
| Sensitive skin/allergies | Very limited spaces |
| Environmental awareness | Those wanting zero maintenance |
| Large plots | Very limited budget |
| Country houses | Intensive use/many people |
Legal Aspects
Framework in Portugal
| Aspect | Situation |
|---|
| Classification | Not specifically regulated |
| Licensing | Same as conventional pool |
| Water quality | No specific parameters |
| Safety | Same general rules |
| Tax | Same as other pools |
Recommendations
| Point | Action |
|---|
| Municipality | Check local regulations |
| Neighbours | Inform about project nature |
| Insurance | Include in home policy |
| Documentation | Keep project and certificates |
**Legal Note**
Although there is no specific legislation for natural pools in Portugal, they must comply with general construction and safety rules applicable to any pool.
Considerations for Margem Sul
Regional Advantages
| Factor | Benefit |
|---|
| Mild climate | Extended swimming season |
| Local biodiversity | Adapted plants available |
| Large plots | Space for regeneration zone |
| Environmental awareness | Receptive market |
Regional Challenges
| Challenge | Solution |
|---|
| Hot summers | Shading, adequate depth |
| Well water (hard) | Prior analysis, adaptation |
| Sea spray (coast) | Tolerant plants |
| Pine trees | Frequent needle removal |
Most Suitable Areas
| Area | Characteristics |
|---|
| Aroeira/Verdizela | Large plots, pine forests |
| Azeitão | Estates, rural environment |
| Palmela | Spacious properties |
| Pegões | Agricultural land |
| Serra da Arrábida | Landscape integration |
Recommended Local Plants
| Plant | Area | Characteristics |
|---|
| Typha domingensis | Margem Sul | Native, very efficient |
| Scirpus lacustris | Wetlands | Excellent filtering |
| Iris pseudacorus | Riverbanks | Decorative, robust |
| Cyperus longus | Margins | Climate adapted |
Converting an Existing Pool
Is Conversion Possible?
| Situation | Viability |
|---|
| Disused pool | Good |
| Old pool to renovate | Moderate |
| Small pool (<30 m²) | Difficult |
| Very deep pool | Requires adaptation |
Conversion Process
| Stage | Description |
|---|
| 1. Assessment | Structure, dimensions |
| 2. Design | Zones, plants |
| 3. Adaptation | Depths, division |
| 4. Installation | Substrate, hydraulics |
| 5. Planting | Suitable species |
| 6. Maturation | 6-12 weeks |
Conversion Costs
| Item | Estimated Cost |
|---|
| Assessment and design | €500 - €1,500 |
| Structural adaptation | €2,000 - €8,000 |
| Biological system | €3,000 - €6,000 |
| Plants | €500 - €1,500 |
| **Total conversion** | **€6,000 - €17,000** |
Maintenance Checklist
Weekly
- [ ] Remove floating debris
- [ ] Check pump operation
- [ ] Observe plant condition
- [ ] Clean skimmer
- [ ] Check water level
Monthly
- [ ] Test pH and oxygen
- [ ] Prune excess plants
- [ ] Check transparency
- [ ] Clean pre-filter
- [ ] Inspect liner/waterproofing
Seasonal (Spring)
- [ ] Restart system
- [ ] Plant new species
- [ ] Divide large plants
- [ ] Check equipment
- [ ] General cleaning
Seasonal (Autumn)
- [ ] Remove fallen leaves
- [ ] Cut dead plants
- [ ] Prepare for winter
- [ ] Protect equipment
- [ ] Reduce circulation
Frequently Asked Questions
Is natural pool water safe for swimming?
Yes, when well-designed and maintained. Biological filtration naturally eliminates pathogens. The water is not sterile, but it's safe and often better quality than river or natural lake water where swimming is practised.
Can I have fish in a natural pool?
It's possible but generally not recommended for swimming pools. Fish produce waste that overloads the system. If you want fish, significantly increase the regeneration zone.
How long until I can use the pool?
The initial maturation period is 4-8 weeks after filling. During this time, the ecosystem establishes itself and water naturally clarifies.
Does a natural pool attract mosquitoes?
A well-designed natural pool with moving water doesn't favour mosquitoes. Larvae need still water. Circulation and natural predators (dragonflies, amphibians) control populations.
Can I heat a natural pool?
It's possible but not recommended above 25°C. High temperatures unbalance the ecosystem and favour algae. If necessary, use passive solar heating.
Conclusion
Natural pools represent a viable and sustainable alternative to conventional pools:
- Zero chemicals for a natural bathing experience
- Low environmental impact and landscape integration
- Reduced operating costs in the long term
- Biodiversity and connection with nature
- Property value through differentiation
They require a different approach to maintenance, more focused on ecological balance than chemical control, but reward with quality water and a unique environment.
If you're interested in building a natural pool in Margem Sul or converting your existing pool, ManutençãoPiscinas can help with consultancy and specialised services. Contact us for a no-obligation assessment.
