Building an ecological swimming poolFebruary 7, 2008
Taking a re-look at the swimming pool
One of the joys of village life captured in many a celluloid film was the old well or tank acting as a swimming pool. Many a summer holiday was spent in splashing around and learning the fine art of swimming, diving and cooling off. Cut to modern times and urban affluence, all high end apartments and quite a few houses boast a swimming pool and club house as recreational facilities for the residents. The notion of the swimming pool in a city is that of clean blue waters with a lot of chlorine in it. In fact a recent visit to a large software giant’s campus was revealing. About 4 kgs of bleaching powder was being applied daily to ensure residual chlorine and to kill the bacteria and germs in the waters.
Swimming pools have generally been seen as water wasters. Not only is evaporation of water a major issue but also the cleaning of the pool regularly meant that a large volume of water was discharged to the drains. Recycling systems have reduced this loss of water and made swimming pools much more water efficient. Recycling systems however are energy intensive and unless a pool has UV treatment systems chlorine continues to be used a lot to clean the waters. The challenge therefore is how do you reduce or eliminate water losses, reduce the use of chemicals and finally reduce the use of energy to a minimum yet have a good pool to swim in. The answer designers are exploring is the bio-pool.
What is a bio-pool? The idea of the bio-pool comes from the idea of bio mimicry. By learning from nature and the balance that nature seeks it is the paradigm that one can do away with or minimize. A bio-pool mimics a natural pond. It has several depths of water to move it thermally instead of using a pump. A selection of special, but usually locally growing, plants is placed strategically to make use of their cleansing as well as oxygenation properties. Typha or bulrush or cattail is a favorite choice because of its ability to establish itself and vetiver is another. Plants with a rhizome (an underground stem) such as canna are also preferred. The usual idea is to remove as much of the nitrates and phosphates as possible. This is done to prevent the excessive growth of algae and the subsequent eutrophication of the waters. An anoxic zone is created in certain parts to help fix nitrates and in other parts.
Care has to be taken not to allow the temperature of the water to go too high. This is done with appropriate shading trees in the right directions. The usual maintenance measures would include the removal of leaves using a skimmer and cleaning the pool of organic material as much as possible.
The bio pool itself is divided into two parts, one with the planted filter and stones called the water regeneration part and the other which is the water part where one swims. The pools are lined at the bottom to prevent seepage of water usually with a UV resistant and tear resistant plastic and then lined with earth.
One such bio-pool perhaps one of the first in the region and definitely in the Bangalore area is at the Eco resort in Hessarghatta called Our native village. Enjoy the swimming there with the usual inhabitants of water bodies such as dragon flies hovering over you and tadpoles at a safe distance in a natural pool.
Water wise is certainly about enjoying the gift of water in an ecologically sensitive manner.