Creating Natural Swimming Pools

Build an environmentally sustainable swimming pool that uses only nature’s plants as a filtering system and requires no chemicals or cleaning.

When Neil Hearn was invited to see the natural swimming pool of one of his customers actually in use, he took the opportunity to investigate since he was building a new home in rural New Zealand.

Natural Swimming Pools Require No Chemicals

Natural swimming pools are those which require no chemicals. They rely instead on the biological filtration created by wild pond and lake plants. The only thing required which is not naturally in place in the wild is a pump to keep the water moving. It’s critical to keep the water moving.

By planting a combination of oxygen producing plants which grow under water, with nitrate removing swamp reeds and rushes on the edges, the entire pool system becomes a complete biologically cleaned system. There is no need for filters or chemicals or pool cleaning – an environmentally sound and sustainable system.

The pool which the customer had built four years earlier grabbed Neil’s imagination and he was particularly struck by the clarity of the water through which a coin on the bottom was easily visible. He decided to create a natural swimming pool for his own property.

Natural Swimming Pools by Michael Littlewood

He referred frequently to a twenty year old book written by Michael Littlewood and entitled, Natural Swimming Pools – Inspiration for Harmony with Nature. The book supplied Neil with many ideas particularly around design.

Building a Natural Swimming Pool

When he began to build his own pool, Neil created a two-metre deep excavation in the shape of a saucer. In the centre of the excavation he built a 400mm thick construction from timber into the rectangular dimensions of a pool. Next came sturdy matting designed to act as a buffer between the stones in the ground and the actual pool liner. Once that was in place the entire pool was lined with a single layer of membrane made from rubber, and designed for use in effluent ponds. The membrane was cut and bonded into the pool corners and then a second layer of the sturdy textile matting was laid outside of the rectangle to act as a buffer for the pool lining.

 

Finally, more than 35 tonnes of scoria was used to fill in the 70m² excavation outside of the rectangle. Then it was time for the plants.

Planting a Natural Swimming Pool

Oxygenating plants grow easily and as movement in the water from swimmers causes pieces to break off, they readily grow into new ones.

Algae that would normally form naturally in a pond is starved by the planting of reeds which absorb the materials that enable algae to grow. Research has discovered a reed which filters e.coli, as well as a nitrate-filtering rush. Between them, these two perimeter plants are able to extract more bacteria than chlorine is able to.

Natural Residents in a Natural Pool

With their plantings only just developing, the Hearns say their pool has attracted a few residents such as tadpoles. Water beetles have discovered the mini utopia as well as dragonflies and the occasional fishing bird hoping for a tadpole.

The deck and and seating has all been built from Fijian Mahogany.

 

Sources: Theresa Sjoquist interview with Neil Hearn – December 2010

©Theresa Sjoquist