The following is an excerpt from Natural Swimming Pools: Conventional Pool Conversion by Michael Littlewood (Ecodesignscape, 2011). The excerpt is from the Introduction.
Imagine a swimming pool, and what do you see? A slab of sterile blue water, surrounded by tiles? It doesn’t have to be like that: imagine instead a pool of fresh, clear water, fringed by native plants and visited by dragonflies. Plenty of people are doing just that: the upsurge of interest in natural swimming pools, which I introduced to Britain in 2000, has convinced many owners of conventional pools to aspire to a natural one. The good news is that converting a conventional pool is usually possible – and much easier and cheaper than starting from scratch.
Natural swimming pools stay clean without any chemical treatment; instead, they emulate the ecosystem of a healthy pond. The principle, conceived in Austria more than 20 years ago, is to establish the elements of a natural system – and then let nature take over. The pool needs to have a surface area of at least 50 square metres and consists of a swimming area, at least 2m deep, which is serviced by a second, shallower body of water. This ‘regeneration zone’ is planted up with locally appropriate marsh and water plants in a gravel substrate. The plants create a habitat for the microorganisms which break down potential pollutants, while the gravel bed acts as a natural filter. Though the swimming area is separated from the plants, you are surrounded by them as you swim – and this seamless blending of environments makes the experience very special.
Once you list the other advantages of a natural swimming pool, it’s not hard to see why many owners of conventional ones are thinking about conversion. Some conventional pools are elegantly designed, but most are visually uninspiring. In winter many are emptied, and they can become an eyesore. A natural swimming pool, on the other hand, is an attractive garden feature all year round. While estate agents routinely warn householders that a conventional pool cannot be expected to add value to their home – potential buyers may view it as a liability rather than an asset – a natural pool can enhance the appeal of your property.
Converting your pool to the natural system will also reduce your maintenance bill. There are no costs for chemicals, energy costs are absent or minimal (the water warms up naturally as it circulates through the shallow regeneration zone), and there are huge savings on water as, unlike conventional pools, natural pools do not have to be emptied every year.
Then there are the health benefits. The chlorine used in conventional pools is a skin irritant, associated with conditions such as eczema, and has also been documented to aggravate asthma. Chlorinated water also contains chemical compounds called trihalomethanes, which are known to be dangerous.
The environmental advantages are huge. In addition to the ecological benefits of the savings on chemicals, energy and water, natural swimming pools are typically built from eco-friendly materials, and they provide a protected habitat for wildlife including amphibians, insects like dragonflies, and many species of birds.
If you already have a conventional pool, you’re halfway to having a natural one. Existing pools can easily be converted as long as there is space to create a regeneration zone. No major upheavals need occur as the main structure has already been built. The excavation, the removal of surplus soil and debris, the drainage, the groundworks, the plumbing and the electrics have already been undertaken – and paid for. Existing materials such as paving slabs, edgings and copings can be reused. If your pool is larger than it needs to be and 40 to 45 per cent of its total area can be spared, the regeneration zone can be built within it. If space is at a premium in the existing pool, the regeneration zone can be built either alongside it or nearby, and developed as a separate natural pond feature.
Natural swimming pools can serve many other purposes. They can be used for fire fighting and as barriers to fires, for emergency water supplies, and as potential heat sources for heat pumps. All of these can reduce household insurance costs, adding to the financial savings of a natural swimming pool, which will not require the costly servicing of a conventional pool.
There are numerous benefits to having a natural swimming pool, both in terms of saving resources and of creating a sustainable facility.
Natural swimming pools can save:
Water: Because a natural swimming pool does not need to be emptied every autumn, thousands of litres of water could be saved. If the average swimming pool has a capacity of approximately 100 cubic metres, that equates to 100,000 litres of water! Even taking a conservative estimate of 200,000 swimming pools in this country, that adds up to 200 million litres of water.
Wildlife: A natural swimming pool can help to save many endangered species, such as frogs, toads, newts, dragon- and damselflies, water boatmen, and many species of birds.
Energy: Less energy is used in a natural swimming pool as the water warms up much more quickly due to the black liner and the shallow water in the regeneration zone. The circulating pump can be operated for free quite easily, using a photovoltaic cell.
Chemicals: No chemicals are necessary, which ensures that there is no danger to the health of swimmers, and this also saves time and expense.
Materials: Existing landscape materials surrounding a conventional pool such as paving slabs, edges, trims, copings etc. can be reused, thereby reducing the burden on landfill sites!
Time: No major upheavals in the garden need to occur as the main structure – the swimming pool itself – has already been built, so large machinery and equipment will not be needed.
Money: The cost of conversion is less than that of building a new pool.
Natural swimming pools can provide:
Educational Resource: A natural swimming pool can serve as an educational resource for children, especially those who do not have access to pools or ponds in their school grounds or local parks. Having a natural pool at home encourages interest in the aquatic environment all year round, though the supervision of a parent or other adult is of course essential.
Reservoir: Natural swimming pools can be used for emergency water supplies and for fire-fighting.
Oasis: A natural swimming pool provides a sanctuary or oasis in the garden, wherever it may be located, at any time of year.
Beauty: Natural swimming pools are far more aesthetically pleasing than their conventional counterparts, whether seen from the air or from ground level, throughout the year. There are no unsightly views of an empty pool in winter, which collects leaves and debris and has to be cleaned out every spring before water filling can commence.
Natural pools offer a wide variety of opportunities for the creation of natural features such as rock pools, beaches, waterfalls, streams, lily ponds and bubble fountains. A very interesting water garden – not just a swimming pool – can be created that will provide users with hours of fun and enjoyment.
Habitats: Habitats can be created for all kinds of wildlife associated with water.
Michael Littlewood is the author of two other books on natural swimming pools, Natural Swimming Pools: Inspiration for Harmony with Nature and Natural Swimming Pools: A Guide for Building.