Orléans la Source wastewater treatment plant

Reusing treated wastewater to preserve clean water resources

Orléans Municipality has initiated an innovative process to reuse treated wastewater from the Orléans la Source wastewater treatment plant in Saint-Cyr-en-Val. The aim is to use this treated wastewater to irrigate landscapes, in particular a large floral park, and avoid having to collect water from the Loiret river.

Artelia was in charge of all engineering aspects of the project, assisting Orléans Municipality from the design of the facilities through to commissioning, as well as with the administrative authorisation process.


The largest tourist attraction in the Loiret region, the Orléans la Source floral park is an open space (35 ha) that receives almost 20,000 visitors a day in the summer. Most of the water used for irrigation comes from the source of the Abîme (source of the river Loiret), but this type of practice is now being questioned due to the drop in the medium level of this river and the increasingly frequent restrictions on water catchment that have to be imposed. Orléans Municipality has therefore studied a more sustainable solution, a project to reuse treated wastewater from the nearby Orléans la Source wastewater treatment plant. This infrastructure, which treats domestic and industrial effluent from the surrounding area on a daily basis and then returns it to the river Loire, represents a very interesting source of water.

Rarely implemented by French local authorities, this kind of process requires fundamental health safety aspects to be taken into account. Artelia therefore worked in close collaboration with Orléans Municipality, government departments ( in particular the regional health agency) and the operators of the wastewater treatment plant and the Floral Park to anticipate any unforeseen incidents as far as possible and find solutions that would enable the project to succeed.

An additional tertiary treatment process, of the sand filter/UV type, followed by disinfection with sodium hypochlorite (to eliminate viruses and bacteria), has been chosen in order to produce treated wastewater of quality A (bathing), which can be used for watering. To reduce the project’s carbon footprint and environmental impact, it was also decided to install the new treatment, storage and distribution equipment in an existing, unoccupied concrete building.