Bassin des filtres - VNF

The Bassin des Filtres is
a unique system in Toulouse

The Bassin des Filtres is a unique hydraulic design. It was built in Toulouse between 1842 and 1843 to filter the water from the Garonne river which was flowing via the Canal de Brienne to supply the Canal de Garonne. 

The Bassin des Filtres is part of a much bigger historic structure that includes the Port de l’Embouchure, which is where the Canal du Midi, Canal de Garonne and Canal de Brienne merge. 

The Bassin des Filtres,
a unique hydraulic system

Water supply for the Canal de Garonne

When the Canal de Garonne, built between 1839 and 1856, needed to be filled with water, the engineers came up with the idea of using the Canal de Brienne to supply the Canal de Garonne, using the waters from the Garonne river.
The Canal de Brienne had been the link between the Garonne and the Canal du Midi since 1776. It joined onto the Canal du Midi at the Port de l’Embouchure, which was easily recognisable thanks to the Ponts-Jumeaux (twin bridges).

The waters of the Garonne collected at Saint-Pierre lock were muddy. To make sure the canal was not silted up, a huge filter was created immediately upstream from the Ponts-Jumeaux in 1842 on the left banks of the Canal de Brienne.

This filter was named the 'Bassin des Filtres', and this was where the waters from the river were filtered before flowing into the Canal de Garonne via an underground aqueduct at the Port de l’Embouchure.

Plan du bassin d'embouchure

Plan du bassin d'embouchure

The Ponts-Jumeaux lock and lock keeper's house

The Pont-Jumeaux lock was also built, at the same time as the Bassin des Filtres. A big lock keeper's house, named the Maison de l'Horloge, was built at the centre.

The Ponts-Jumeaux lock has a dual purpose. On the one hand, it is the water inlet into the Bassin des Filtres, and it was also designed to prevent muddy waters from entering the Port de l’Embouchure.  

How does the Bassin des Filtres work?

The Bassin des Filtres structure

The Bassin des Filtres is made up of two basins that are perpendicular to the Canal de Brienne. The first one is filled with water from the Garonne river, via the Canal de Brienne. This water then flows into the second basin via a filtering system that does not allow mud and other sediments to pass through.

Once the water has been decanted, it flows through a filter system featuring a link between the two basins. The clear waters from the second basin are then diverted via an underground aqueduct to the Canal de Garonne.

The dam warden's house in Les Amidonniers

To ensure this site operates correctly, on-site housing is provided for the dam warden. This means that they can intervene quickly when the Garonne overflows.

The dam warden's house was built in 1842 near the Chemin des Amidonniers and it is hard to miss. An ancient cedar towers over the house and it has now been transformed into a traditional 'guinguette'.

Did you know?

The Canal de Garonne allows boats to sail between Toulouse and Bordeaux, without having to use the Garonne river, which can be challenging.

A place for walking and tourism in the centre of Toulouse

Besides its technical purpose, the Bassin des Filtres is also a remarkably scenic place. The banks are open and unspoilt, making this a great place to go for a stroll. A green lung in the Amidonniers district!

In the 19th century, this place was turned into a destination for tourism, with a hotel and wooden chalets were built for the Canal du Midi employees.

The Bassin des Filtres is no longer used to filter water today, but we can still see evidence of its original purpose in the architectural features.

It is also a real haven of greenery with hundred-year-old trees right in the centre of Toulouse!

Toulouse, stopover town on the Canal du Midi