In the west of France, in Brittany, the island of Groix has been on drought and water shortage alert since June. The arrival of many tourists does not help the situation, water consumption doubles every summer. To remedy this problem and avoid having to cut off the running water to the inhabitants, the municipality and the agglomeration of Lorient have installed a seawater desalination plant. A temporary system, launched urgently and which should be dismantled in October.
On the island of Groix, in the spring, everyone watched the Port Melin dam, the main source of drinking water for the town. The water level was dropping dangerously. The mayor, Dominique Yvon, was worried: “Soften, we claim with a sneer that in Brittany, it rains all the time, but for five months, we must not have had three days of rain… It is all the same an important sign of the climate change which is under our eyes. We are lucky to have the Atlantic, which is an inexhaustible source of water. »
This is why, to avoid the cut of drinking water, the municipality and the agglomeration of Lorient turned to the sea. The water desalination plant is located on the cliff, above the dam that it supplies fresh water. ” We installed seawater pumping equipment on a raft. The water is then transported by floating pipes which go up along the dam, to be stored in a tarpaulin, explains Sandrine Delemazure, director of the water and sanitation service for the Lorient conurbation. Then, the water is routed to boxes which are used to separate the salt from the water, and therefore, to produce fresh water. We also have a discharge on this installation, very loaded with salt, because the salt that we remove on one side, we add it on the other. »
A solution that does not only have advantages
This solution requires a lot of energy and can damage marine ecosystems. Quentin lives in Groix. He thinks about the environmental consequences of this installation. ” I am a diver, what worries me is above all that the desalination plants discharge salt into the sea, which is already salty. Below, there are waters that bring together protected species, such as seahorses, and we are resalinizing water that is already increasing in resalinization globally. »
It is for these reasons that the factory only has a temporary permit. According to Nicolas Roche, professor at the University of Aix-Marseille, as long as seawater desalination is used in small proportions in the country, its environmental impact remains limited. However, this solution is not sustainable. “ Desalination acts as a palliative, we are more on a dressing logic, he explains. We try to respond to a temporary crisis, except that it’s not a temporary crisis, it’s a crisis that will settle over time. It really needs to be included in a global scheme linked to the uses of water. »
This means better water management, avoiding losses or even reducing its consumption. Another avenue for reducing the pumping of groundwater would be the reuse of water. In France, only 0.6% of wastewater is recycled compared to 8% in Spain and 14% in Italy.