Water reuse in an industrial context - Internal/External water sources and uses: framework, potential, technologies, and feedback

Synthesis

Disclaimer: The content of this publication is based on the state of knowledge and the regulatory framework in force at the time of publication of the documents

Context and objectives of the study

The industrial sector is having to adapt to an increasing number of drought periods and water use restrictions. The reuse of non-conventional water appears as an operational and structuring solution to limit water withdrawals, while also limiting the impact of discharges. It is part of an industrial ecology approach, and it also allows industrial operators to integrate locally and adapt to the local water context.

This practice is still recent, sometimes complex to implement, and can take many different forms. In France it is governed by an evolving regulatory framework, aimed at reconciling industrial performance, protection of the environment and management of health risks.

In this context, the RECORD association wished to produce a guide for project developers involved in water reuse in the industrial sector. This guide is intended to be accessible to project developers who are new to the subject. It is linked to, and refers to, a detailed study report, which is the subject of this summary. The outline below follows the outline of the report.

Framework elements

A first section, “Framework elements”, details: the terminology commonly used (mainly drawn from NF ISO20670), the main French and international standards currently in force, the forms of reuse encountered in the industrial sector (referred to here as “types” of reuse), and also the framework and regulatory texts involved.

While the study aims to direct the reader towards the regulatory texts and references associated with their project, it does not provide a regulatory summary: the texts and possible situations are too numerous. Only the context for the agri-food industry is detailed. A comparative regulatory analysis of other countries is also included in the study.

Three types of industrial water reuse are thus defined. They allow a clear distinction based on the origin of the water (the source), the uses, and the managers and owners in charge of and responsible for the project:

• Type 1: mobilisation of a non-conventional water source not originating from an industrial site, for example treated wastewater discharged by a municipal wastewater treatment plant (WWTP), for uses on an industrial site. This type may involve a local authority in charge of municipal sanitation;
• Type 2: reuse of a non-conventional water source originating from an industrial site (rainwater, process water, cooling water, etc.) for uses on an industrial site, whether the same site or a different one from which the water originated. This type, which only involves industrial operators, is broken down into three sub-types:
  • Type 2a, reuse in a closed loop for a single use at one industrial site;
  • Type 2b, cascading reuse, where water produced by use A supplies use B, which generally requires a lower quality level;
  • Type 2c, an identical cascade but between two different industrial operators, as part of a local synergy.
• Type 3: reuse of a non-conventional water source originating from an industrial site (rainwater, industrial WWTP water, process water, cooling water, etc.) for non-industrial uses within the surrounding territory (e.g. municipal uses, farmers, environmental recharge, etc.).

The framework and regulatory texts differ depending on the type of water reuse. They also differ depending on the nature of the use: water reuse is thus possible and regulated for the following categories of use: 

• Category 1 groups domestic uses (toilet flushing, watering of green spaces and vegetable gardens, washing of laundry and indoor floors, cleaning of outdoor surfaces, decorative fountains, etc.), set out in a closed list under Decree No. 2025-239 of 14 March 2025.
• Category 2 covers the preparation of food and food products in companies of the agri-food sector.
• Category 3 groups all other uses, distinguished between uses internal to the industrial site (processes, vehicle washing, cooling, etc.) and uses external to the surrounding territory (irrigation, land spreading, urban cleaning).

Only water intended for human consumption remains authorised for the most sensitive domestic uses (drinking, cooking, personal hygiene) as well as for the preparation of food products.

The body of regulatory texts mobilised is extensive and very recent: the decree and order of 14 March 2025 for domestic uses within regulated industrial installations, Decree No. 2024-33 and the order of 8 July 2024 for water reused in the agri-food sector, the decree of 29 August 2023 and the orders of 14 and 18 December 2023 for rainwater and treated wastewater, among other texts. Many situations, such as the reuse of rainwater or groundwater dewatering, are nevertheless not covered by any specific framework: State authorities then favour a case-by-case approach, through single points of contact set up within the DDTM (departmental territorial and maritime directorates). Flowcharts cross-referencing the three categories of use and the three types of reuse allow project developers to identify the texts that apply to their case.

The comparison with other countries' regulations (Italy, Spain, the United States and Australia) shows that all of them require a risk management plan to be drawn up in addition to compliance with minimum thresholds. These minimum threshold values are difficult to compare from one country to another, given that usage conditions and constraints differ.

A standardisation framework operates at three levels: international with ISO, European with CEN, and national with AFNOR, within which a “RENC” commission (use of non-conventional water) includes a working group dedicated to industrial uses. No equivalent European working group currently exists. Internationally, ISO technical committee TC 282 leads the standardisation of water reuse; its subcommittees directly cover industrial uses.

Project approach and risk analysis

A second section of the report, complemented by the accompanying practical guide, details the steps a project developer should follow, from the initial idea through to a sustainable and secure implementation, with a particular focus on health risk assessment methodologies.

The project approach generally follows five steps:

• Identification of the drivers behind the initiative: reducing withdrawals (financial reasons, environmental constraints, search for autonomy) and/or reducing discharges (to the environment or to the public sewage network);
• Diagnosis of water flows on the site, aimed at characterising the sources, uses and wastewater produced in terms of volumes, flow rates and quality, which may require the implementation of specific monitoring;
• Feasibility study, combining an analysis of the applicable regulatory framework, a technical and financial study of suitable supply and treatment solutions, the operational set-up with any partners involved, the search for funding, and a multi-criteria cost-benefit approach factoring in the impacts on water resources; this step should lead to a “GO / NO GO” decision.
• Regulatory procedures (authorisation, declaration, amendment of a site permit) to be carried out in close cooperation with State services, generally accompanied by a health and environmental risk assessment.
• Implementation: detailed engineering studies, agreements with partners, funding applications, construction, followed by dedicated project monitoring based on risk and performance indicators, complemented where necessary by analytical water quality monitoring required by State services.

It should be noted how important it is to share this approach as early as possible with State services and with the other stakeholders in the territory involved and/or affected.

The health risk analysis links risk assessment and risk management through a methodology inspired by the HACCP approach, recommended by ANSES and adapted to the health risks associated with water reuse. It is based on four steps:

Specific attention is also given to occupational risks associated with the use of non-conventional water: these risks, which include health conditions as well as exposure to chemical substances, must be included in the site's single occupational risk assessment document. Prevention relies in particular on separating non-conventional water networks from drinking water networks from the design stage, signposting points of use, limiting techniques that generate aerosols, automating cleaning operations and, where collective measures prove insufficient, providing suitable personal protective equipment.

Potential for industrial water reuse

In 2022, total declared water withdrawals in metropolitan France and Corsica amounted to around 33,845 Mm³, the majority of which was for the Energy sector, mainly EDF's nuclear operations, whose representative withdrawals are close to 21,500 Mm³/year. The “Industry and economic activities” category accounted for 2,243 Mm³ withdrawn in 2022. The potential for substitution is markedly higher for groundwater withdrawals, around 856 Mm³/year and more closely linked to industrial processes, than for surface water withdrawals, around 1,257 Mm³/year and often associated with open-loop cooling, or for coastal withdrawals, around 130 Mm³/year, which offer limited reuse potential given their salinity and rapid return to the environment. The sectors that consume the most water and are most targeted for reuse are chemicals, metallurgy, the agri-food industry and the paper and cardboard industry; at national level, chemicals and metallurgy account for 47% of the water uses identified in the Type 1 potential analysis, a proportion that rises to 72% along the coast.

The potential of each of the three types of reuse was assessed separately:

• For Type 1, the analysis considers regulated industrial sites located within a 5 km radius of urban WWTPs serving more than 50,000 population equivalents. At national level, the available potential resource, estimated at 2,970 Mm³/year, is far greater than the needs of the industrial operators identified, around 1,715 Mm³/year; along the coast, however, the available resource (650 Mm³/year) and the potential uses (750 Mm³/year) are more closely balanced, confirming the particular interest of coastal areas highlighted by the study, notably around industrial zones.
• For Type 2, which is harder to quantify at national level due to the lack of consistent data on quantitative pressure on water resources across territories, the study illustrates the potential for inter-industrial pooling, whereby neighbouring industrial operators could consider exchanging water depending on their respective uses and discharges.
• For Type 3, the analysis targets agri-food sites with an isolated discharge point located near large cereal farmland, covering more than 50 hectares within a one-kilometre radius: 151 industrial sites in metropolitan France meet these criteria, representing a potential resource of 47 Mm³/year for around 15,000 hectares of farmland, equivalent to roughly 3,100 m³ per hectare per year.

At European level, a 2023 study estimates that wastewater produced by industrial operators in the European Union exceeds 25,500 Mm³/year, of which up to 80% could theoretically be reused using suitable treatment technologies, at a cost representing around 1.5% of European GDP and an increase of around 4.1% in industrial energy consumption.

Overview of the main treatment processes

A comprehensive review of the main treatment processes used for water reuse resulted in nine technical fact sheets detailing, for each process, its operating principles, performance levels, main advantages and main limitations (without replacing the need for a project-specific technical study). These processes fall into four families.

• Pre-treatment processes include coagulation-flocculation, effective against suspended solids, colloids and metals, at a low to moderate cost but generating sludge that must be treated, as well as mechanical filtration, simple, robust and low-cost, but ineffective against viruses, bacteria and micropollutants.
• Advanced treatment processes include membrane filtration and reverse osmosis, which achieve very high water quality by removing salts, viruses, bacteria and micropollutants, but at a moderate to very high cost and, for reverse osmosis, with significant energy consumption and the production of a concentrated reject stream.
• The thermal process of evaporative crystallisation achieves minimal discharge and potential mineral recovery, at the cost of a complex, very expensive and energy-intensive operation.
• Finally, finishing and disinfection processes include UV treatment, fast and free of chemical residue but with no lasting effect, advanced oxidation, broad-spectrum but expensive and complex, chlorination, effective and low-cost but generating potentially toxic by-products, and ozonation, highly effective against micro-organisms and organic compounds but expensive and with no lasting effect.

Case studies

Finally, eleven typical case studies of water reuse have been examined. They are closely inspired by feedback from experience (REX) on operational sites or sites currently under study, but they are “fictional”: they sometimes combine elements drawn from several real cases, and have been deliberately adapted to highlight specific situations and constraints. 

The selection and definition of these case studies was carried out jointly by Ecofilae and the RECORD study steering committee. These eleven case studies aim to be:

• Complementary and representative, so as to cover the full “range” of forms of water reuse of interest to industrial operators defined previously;
• Of socio-economic and environmental interest within the French territory.

They thus illustrate the reuse of water from urban WWTPs for cooling purposes (case study No. 1) or for cleaning and dust suppression (case study No. 2); the recycling of acid regeneration water (case study No. 3, shared by EDF for the Blénod power plant) or boiler blowdown water (case study No. 4, shared by EDF for the Martigues power plant) to supply industrial networks; the recovery of stormwater runoff for industrial cleaning (case study No. 5); the reuse, in the agri-food sector, of water from raw materials for food preparation (case study No. 6) or of water from an industrial WWTP for cleaning premises and equipment (case study No. 7); the reuse of industrial roof runoff for domestic-type uses, including in laundries (case study No. 8); the energy recovery of steam produced by one industrial operator for the benefit of a second operator's heating network, where water acts more as a heat carrier than as a reused resource in the strict sense (case study No. 9); the reuse of water from an industrial WWTP for public urban uses such as cleaning and watering of green spaces (case study No. 10); and the reuse of raw or treated effluent in agriculture, for irrigation or land spreading (case study No. 11).

Summary of the case studies analyzed

These case studies echo several emblematic examples of feedback from experience, both French and international, which are also presented in the guide.

• In Los Angeles, treated wastewater from the Hyperion El Segundo WWTP, which serves 11 million population equivalents, has been reused since 1985 to supply industrial cooling circuits, thanks to advanced treatment combining membrane bioreactors, reverse osmosis and UV disinfection coupled with advanced oxidation.
• In Australia, at Wollongong, treated wastewater from the municipal plant has been supplying the BlueScope steelworks at Port Kembla, in New South Wales, since 2005, notably for suppressing coal dust.
• The Kalundborg industrial symbiosis, in Denmark, launched in the 1970s, illustrates a cascading system linking several industrial operators from the energy, refining and pharmaceutical sectors, saving several million cubic metres of water per year while limiting discharges.
• In France:
  • The Guéret urban area, in the Creuse department, draws on an open reservoir holding 65,000 m³ of stormwater runoff, providing three months of autonomy, to supply a shared network serving several industrial operators within the same business park.
  • At EDF's combined-cycle gas power plant in Martigues, in the Bouches-du-Rhône department, recycling boiler blowdown water back into the industrial water network reduces raw water withdrawals by 25 to 30%, or around 90,000 m³/year, without requiring any additional chemical treatment.
  • The COOPERL cooperative, in Lamballe in the Côtes-d'Armor department, recycles part of the process water from its pork processing activities, after biological treatment combined with ultrafiltration and reverse osmosis, for cleaning purposes within its facilities.
  • At the Monin industrial site, in the Cher department, nearly 45,000 m³/year of treated wastewater — close to 90% of effluents — has been reused since 2024 for cleaning purposes, with sugar-rich concentrates additionally recovered through methanisation.
  • Finally, the sugar producer Cristal Union recovers more than 7 million m³ of water per year, from beet washing and pulp extraction, for use in agriculture by partner farmers, through land spreading in autumn and winter followed by crop irrigation in spring and summer.

Conclusion

The study and its accompanying guide thus provide a comprehensive overview of industrial water reuse in France:

• A regulatory framework that is recent and structuring but still incomplete and under development;
• A significant potential that is nonetheless highly uneven depending on the type of reuse and the territory concerned, particularly along the coast and within inter-industrial synergies;
• Mature treatment technologies capable of achieving the quality levels required for each use;
• And a diversity of operational feedback from experience, both French and international, demonstrating the technical, regulatory and economic feasibility of the approach.

The report and its accompanying guide thus offer industrial project developers a comprehensive methodological framework, from identifying the drivers behind the initiative through to the secure implementation of their project, while underlining the importance of early dialogue with State services and other stakeholders concerned or affected within the territory.