From Rain to Pond: "Individually Constructed Wetlands," a Closed-Loop Water System in the French Pyrénées

Ecological pond in their garden

I was late. The winding path to Michel and Marie-Andrée’s off-grid home was ahead, lined with spring flowers, bird calls, and the smell of damp earth. I hurried along, the mountains towering quietly around me. By the time I reached their hand-built wood house, they welcomed me with warmth and a readiness to share their story.

Ecological Books from the US in the 1970s, when Michel studied at the University of Montreal

Their home is entirely self-sufficient, the result of three years of labor and a lifetime of learning. Michel was admitted to a master's degree at the University of Berkeley but chose the University of Montreal where he received a scholarship. He studied ecology there with Professeur Dansereau.

“All this knowledge existed in the U.S. 50 years ago,” he told me, pulling out a shelf of worn, beloved books. “Solar, wind, hydrolic power, geodesic domes... the Americans were the leaders in environmental technology back then.”

I had come to write about their pond—an elegant feature in the garden, shaded by lilypads where fish glided just beneath the surface. But my hosts were quick to correct me.

“You can’t just write about the pond,” they said. “It’s the final step in our water cycle.”

The Rainwater Begins Its Journey

Outside, they showed me the slate roof. Rainwater flows through zinc gutters to a small shelter attached to the house. This shelter hides a float tank which allows the first 150 liters of water to be diverted from the roof, intended only for the garden. Then the water is directed underground to three filtration tanks - stone, charcoal and sand - the purified water enters three 1,000 liter tanks.

Detail of the rocking system that moves the water into the different tanks

From there, the water is pressurized and passed through three more filters for domestic use. Drinking water benefits from an additional layer of filteration by ceramic filter and activated carbon under the sink. According to Marie-Andrée, their water is cleaner than that of the city water because it is free from pollution from agricultural or human origin.

“The materials are important,” he explained. "Using the wrong ones pollutes the water and earth, instead of protecting it.”

Reeds (Phragmites) as Natural Filters

When water leaves the house, it does not flow into the drains. It flows through two planted reed beds—each filled with gravel. The reeds (Phragmites australis, or common reeds) were collected from the nearby river.

A first pool called "aerobic" filters the water using bacteria that live in the air, the other "anaerobic" takes care of those that live in the water. When the water reaches the pond, it’s been naturally purified—and it shows. The pond is teeming with life: fish, acquatic plants, and even fry, baby fish frolicking among the water lilies and horsetails.

The natural water filtration system using common reeds from the river nearby

A System in Balance

Rainwater from the other side of the roof flows directly to a cisterne buried in the garden for irrigation. Dry toilets further reduce water consumption. Since 2011, Michel and Marie-Andrée have never used a drop of water from the public network. It is important to note that they use 30 liters of water per person per day, whereas the average person in France uses 150 liters of water per day. Another caveat to note, these systems are difficult in reality though, especially in places like the United States, because of regulations and most houses must be connected to the grid.

"One must change their habits and embark on a journey of joyeuse sobriety."

Their closed-loop system not only meets their daily needs but also nourishes the land around them with compost from toilets, household waste and plant sized shredded material.

Closing the Loop

I left with more than I expected: not just a story about a beautiful pond, but a deep respect for the invisible systems sustaining it. The pond is just the visible tip of a water cycle that begins with a cloud and ends in fish swimming under lilypads.

As I walked toward the gate, Michel called out to me.

“I have a book for you,” he said, handing me a well-worn copy of Introduction to Energy: Solar, Water, Wind & Biofuels—published in 1974 by the Portola Institute.

Its pages were filled with small-scale systems designed for individuals and communities - like those they have incorporated into their home. It was through their house that I discovered this wisdom, not as a theory, but as a living practice. A knowledge that quietly endures, thanks to people like them, who not only protected it but built their lives around it, allowing it to endure so that others could discover it.

Lots of baby fish swimming in the natural pond

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