Dardennes Dam

In brief

At the foot of Mont Caume, at Le Revest-les-Eaux, the Dardennes dam is Toulon's hundred-year-old water tower. Built just before the First World War, it still helps supply Toulon and its area with drinking water.

How does it work?

It is a gravity dam in masonry and concrete, slightly curved:

• It blocks the little river the Las, and collects the water of very abundant springs (those of the Ragas and the Foux), which come out of a limestone rock full of holes (called karstic).
• The water of the Revest lake is sent nearby, to a plant where it is filtered and disinfected with ozone before being distributed.
• Between 2020 and 2022, the outlets and the watertightness of the dam were renovated so that it can serve for the next century too.

Key facts

• Height: 31.6 m. Crest length: 154 m.
• Reservoir: 1.1 million cubic meters.
• Built between 1910 and 1912.

Words to know

• Karstic: said of a limestone rock hollowed out by water into holes and passages.
• Ozone: a gas used to disinfect water.

Did you know? In karstic rock, whole rivers can flow underground: the water disappears into a hole, travels in the dark, then sometimes comes out several kilometers away, as a spring.

Going further

A karstic rock is like a sponge full of holes: rain soaks in quickly and comes out lower down in very abundant springs. But the water is hardly filtered by the rock, and it can carry impurities. That is why Dardennes water is filtered and disinfected with ozone before it reaches the taps.