Swimming is a major pastime for expats in Cambodia, who are more than willing to trade intolerable temperatures and humidity levels for a little bit of eye-stinging caused by highly chlorinated hotel pools.

But over the last few years, natural pools, which use biological instead of chemical methods to keep the water clean, have been gaining popularity in Europe, and last week marked the first anniversary of the first natural pool to start up in Cambodia.

Mathieu Damperon opened the Au Cabaret Vert eco resort in Battambang last September, and the natural pool one year ago. He spoke to 7Days about how it stands on its first birthday.

How does swimming in a “natural pool” compare to swimming in a normal pool?

It’s very sweet for your skin. You can open your eyes underwater and drink it, just like a river. The guests really enjoy it and sometimes come just to taste it. They do have to take a shower before swimming though, especially if they’ve been wearing sunscreen – the plants don’t like that.

When did you first hear about the concept of natural pools?

I heard about them for the first time three years ago when I lived in France. When I looked into the concept, I was sure it would be great for my eco resort. No salt, no oxygen pump, just plants filtering water; a pool with a total respect for nature. I was very excited about it.

How did you build it?

I checked so many books, websites and forums, and had a lot of discussions over Skype with the owner of Bionova, which built the first public natural swimming pool. After I created the filtration basin, I looked for Cambodian plants that could work with it. Taber Hand, the director of the Wetlands Work! NGO gave me a lot of advice.

What plants and animals are in your pool?

The filtration system works with several different kind of plants: water hyacinth; water lettuce; several sedge species; papyrus species; salvinnia species; water lilies and lotus plants to make it easy on the eyes.

I have four or five fish inside my pool. The fish eat the plants that grow, which provides better filtration.

Do many expats come to use the pool, or is it mainly just your guests?

Many expats come here, especially from Phnom Penh and Siem Reap for a weekend getaway. We propose an eco tour to discover the Battambang countryside and after a day they really enjoy the natural pool (especially with a cocktail).

Some expats came to us at the beginning, when the pool was green. They tested it out, but first they asked a lot of questions. When they returned they asked if we’d changed the water. Absolutely not. It is the same water, but now the ecological system is perfect and the water is very clear.