When you open your kitchen tap to fill a carafe, when you take a shower, when you flush a toilet, and when you live in a town in the Nantes metropolis, you do not don’t think that the water comes from the longest river in France. That the water is taken there, and that the route it follows to the individual’s home is not a long, quiet river. A series of rigorous steps guarantees populations a quality product.
If the Loire offers a supply of raw water to meet the drinking water needs of the metropolis. She is the subject of all attention. Nantes Métropole’s public water policy aims to improve water quality, secure its use as a resource and, more broadly, protect and restore aquatic environments and waterways.
Water is the most controlled food in France
The upkeep, maintenance or renewal of equipment are thus at the heart of the quality approach carried out by the agglomeration. At each stage of the water cycle, permanent analyzes and controls ensure good water quality. In order to adapt to the needs of tomorrow, Nantes Métropole began modernizing its water plant in 2010. It is the most controlled food in France.
At a time of ecological bifurcation, dear to Johanna Rolland, president of Nantes Métropole, this new equipment, with an investment of €90 million, will allow water treatment to be more secure and adapted to climatic hazards induced by the muddy plug.
For Robin Salecroix, vice-president of Nantes Métropole responsible for water and sanitation policy
“Water is a common good that we must protect and whose supply we must secure for years to come. The impacts of climate change on the water cycle (droughts and floods) remind us that we must continue and further strengthen our efforts in this area. Since the start of the mandate, the acceleration of our public water and sanitation policy has been illustrated in numerous ways.
Beyond the delivery of the new water plant for a total amount of €90 million, the future master plan sanitation, submitted to the Metropolitan Council on June 28, will dedicate a budget of 800 million euros for investments over the next 15 years.
With a dual objective: to make our public service more reliable and to drastically reduce our environmental footprint. The diversity of the actions we carry out also includes the reform of water pricing and the sustainability of social pricing, the resource saving approach in the 24 municipalities and even the connection work for vulnerable populations. . »
€90 million to secure the supply of drinking water
The Roche factory was aging. It consisted of around twenty works of different ages, some of which were reaching the end of their life. Nantes Métropole began modernization in 2010. Nearly two thirds of the facilities were rebuilt, ultimately creating a more compact and efficient factory. The La Roche water plant today reaches a guaranteed treatment capacity of 160,000 m³/d, with a possible extension to 200,000 m³/d.
The La Roche factory covers 12 hectares on the banks of the Loire. This new drinking water treatment plant has five new buildings. These notably house new technical processes intended to perpetuate the quality of the water, in particular a more efficient decantation stage with the process « Actiflo ». This is followed by a series of new sand filters and a disinfection process using ultraviolet lamps which constitutes additional protection against parasites.
With a budget amounting to €90 million, including €71.5 million financed by Nantes Métropole, the Loire-Bretagne Water Agency contributed €12.5 million and the Loire-Atlantique Department at €6 million.
The muddy plug clogs the Estuary
The natural phenomenon of muddy plugs, characteristic of estuaries, is a problem that affects drinking water production in Nantes. It can be encountered mainly during periods of low water (when the flow of the Loire is very low) crossed with high tidal coefficients. The sediments loaded with organic matter agglomerate and form a zone of very high turbidity.
The water from the Loire is then excessively loaded and is likely to temporarily reduce the treatment capacity of the La Roche plant. More efficient, the new installations will be able to more easily treat this water laden with turbidity and thus maintain the conformity of the drinking water produced for the inhabitants of the region.
Nantes Métrople implements a social water policy
While water is a public good, essential to life, the rising cost of energy makes it difficult, if not impossible, to pay your water bills. The Metropolis is implementing a social water tariff which will enable 6,400 households to cope. The bill will not exceed 3% of household income.
