Plant-filtered swimming pools that do not use chemicals may be built for public use. A government health body is currently evaluating potential health risks to the idea. Naturally filtered pools are currently available to build privately but only one is open to the public in France.
The Ministry of Health has granted special authorisation for the public pool in Combloux near to Megève in Haute-Savoie. Despite its mountain location the design of the pool keeps the water temperature at 26°C through its layout and filtering processes.
It uses no fuel, no renewable energy and does not change its water.
Swiss company Bioteich has installed more than 100 of these pools fro private clients in France in the past year.
President Bernard Depoorter said: "The majority of our clients are attracted by the idea of having and 'extra garden' but of an aquatic nature and which looks pretty all year round."
The process uses several different basins filled with plants to clean the water which then fills the swimming pool. Water falls from a cascade into a regenerating zone were it is oxygenated and heated in shallows lined with white pebbles to reflect more heat into the pool.
It then moves into the main bathing area before being drawn into the filtration section which is lined with plants specifically chosen for their ability to filter out organic material.
The water is kept moving constantly so it does not stagnate.
While the cost of construction is similar to that of a normal pool, the natural pools need to cover a wider area so tend to be more expensive. For the process to work the filtration and regeneration zones must be at least one and a half times the size of the bathing area. Biotech estimates the minimum cost of installation to be €600 per square metre.
This article originally appeared in The Connexion, July 2008.
