In what ways can this water be reused?

Non-potable water can potentially be used for a wide range of purposes, for example:

• agricultural: direct irrigation or supplying irrigation canals;
• industrial: energy production, supplying cooling systems in cooling towers, car-wash facilities, etc.;
• urban: watering green spaces, washing roads, firefighting, district heating, high-pressure cleaning of sewer systems, etc.;
• domestic: flushing toilets, washing laundry, cleaning indoor floors and outdoor surfaces, watering vegetable gardens, etc.;
• recreational: irrigating golf courses, supplying water to lakes, ornamental ponds or water bodies used for sports (canoeing, sailing, windsurfing), etc.;
• environmental: artificial groundwater recharge, refilling water bodies, irrigating forests or wetlands, etc.

In some countries suffering from high water stress, non-potable water can be used to produce drinking water.

ANSES’s role

The Agency conducts expert appraisals in the area of water reuse to assess the risks to health and the environment:

• prior to establishing the regulatory framework;
• in support of the competent authorities with draft regulations;
• on experimental projects.

Its risk assessments consider the hazards inherent in each type of water that is to be reused, the treatment methods available for the intended purposes, and the control and monitoring measures required to manage them.

 What water reuse solutions are currently authorised in France?

In France, the following uses of non-potable water were authorised for the summer of 2024:

• rainwater, freshwater, well and borehole water, greywater (from showers, baths, washbasins and washing machines) and water from communal swimming pools used for domestic purposes;
• reuse by companies in the food sector;
• treated urban wastewater used for agricultural irrigation and watering green spaces;
• treated urban wastewater used for other purposes, such as urban uses.

Reuse of non-potable water for domestic purposes

The Decree and Ministerial Order of 12 July 2024 on the use of non-potable water authorise the use of five types of water, each with a specific contamination profile:

• rainwater collected from inaccessible roofs,
• freshwater,
• water from wells and boreholes,
• greywater from showers, baths, washbasins and washing machines,
• water from communal swimming pools.

This water can be used for the following domestic purposes, in private homes or in certain non-residential buildings (including their outdoor areas):

• washing laundry;
• washing indoor floors;
• watering vegetable gardens;
• supplying decorative fountains not intended for drinking water;
• disposal of human excreta (toilet flushing);
• cleaning external surfaces, including washing vehicles at home;
• watering green roofs/walls and green spaces belonging to the building.

Depending on the type of non-potable water, the purpose in question and whether or not the building hosts any vulnerable people, the use may require authorisation from the Prefect or just a declaration.

In 2023, the Agency issued an opinion on the draft regulatory framework for these types of water for the domestic purposes mentioned above. It stated that the use of non-potable water for domestic purposes introduced potential health risks for users, which vary depending on the biological and/or chemical quality of the raw water and the intended uses. ANSES therefore recommended that all purposes involving the circulation of non-potable water inside buildings be governed by quality criteria to limit the impact of accidental mixing of water.

ANSES had also previously published two reports and opinions:

• In 2015, based on the data available at the time, the Agency had stated in its opinion that the reuse of greywater in homes could only be considered for strictly limited purposes, in geographical environments prone to sustained and repeated water shortages. It had recommended that, subject to the implementation of appropriate treatment and risk management measures and compliance with precise quality criteria, treated greywater could be reused for only three domestic purposes: flushing toilets, watering green spaces (excluding vegetable gardens and agricultural uses) and washing outdoor surfaces without generating aerosols, i.e. without the use of high-pressure cleaners.
• In 2016, the Agency had issued an opinion on the use of rainwater for washing laundry in private homes. Due to a lack of available data on this practice, the Agency had recommended not using rainwater to wash the laundry of vulnerable people, mainly young children, immunocompromised individuals and people receiving hospital care at home.

Find out more:

• Opinion on the "draft decree and ministerial order on the use of non-potable water for certain domestic purposes"
• Recycling of greywater in households: a practice in need of regulation
• Use of rainwater for washing laundry in the home: ANSES's recommendations

Water reuse by companies in the agri-food sector

Because of their activities, some agri-food industries require enormous quantities of water and have therefore been seeking alternatives to potable water for four types of use:

• Where there is no contact with foodstuffs. For example, water used in cooling or heating circuits;
• Indirect contact. For example, water used to wash surfaces that come into contact with foodstuffs;
• Direct contact. For example, water used for washing raw produce;
• As an ingredient in foodstuffs.

The water that can be reused, with or without prior treatment depending on its type, also varies. It can include wastewater treated in sewage treatment plants, water used for food preparation tasks and water extracted from food raw materials. The risks of contamination of foodstuffs are therefore highly variable depending on the purpose and the type of water used.

The Decree of 24 January 2024, the Decree of 8 July 2024 amending the Public Health Code and the Ministerial Order of 8 July 2024 lay down the purposes, conditions and requirements under which water may be reused in agri-food industries.

In its opinion on the regulatory framework for the use of this water, ANSES stressed the major health issues associated with this reuse, which therefore requires considerable technical expertise and vigilance with regard to the quality of the water produced, especially if it comes into contact with or is used in the manufacture of food. Professionals and government departments alike therefore need to pay special attention.

The Agency thus recommended:

• eliminating the most significant risks at source, by avoiding reused water as an ingredient in foodstuffs or in direct contact with raw produce undergoing no further processing before consumption, and by ruling out certain categories of wastewater, such as water from toilets;
• an overall approach to the associated impacts that also takes account of worker health and the impact on the environment;
• including new requirements in terms of separation, identification and absence of backflow between circuits for the different categories of water, particularly the circuit for potable water.

Reuse of treated urban wastewater for watering green spaces or irrigating crops

In France, the reuse of treated urban wastewater is seen as a promising alternative for irrigating crops or watering green spaces. In certain situations, this practice could in fact help prevent water shortages and preserve water resources, mainly during periods of prolonged drought or in areas where water resources are scarce.

Since 2010, the conditions under which treated wastewater can be reused for irrigating crops or watering green spaces have been regulated, in order to prevent the health risks associated with this practice.

Between 2008 and 2012, ANSES conducted health risk assessments that helped establish the French regulations governing the conditions under which treated wastewater can be reused for these purposes. In particular, the Agency pointed out that professionals employed to carry out watering – as well as residents and bystanders – may be exposed to spray during such reuse of treated wastewater. As a result, the Agency issued several recommendations calling for the regulatory provisions to be supplemented, in particular, specific technical requirements for spray irrigation with treated wastewater (maximum wind speed, safety distance) and recommendations for limiting the exposure of residents, bystanders and professionals by informing the public or prohibiting access to sites during and after irrigation.

Since 2020, the reuse of treated urban wastewater for agricultural irrigation has been governed by European Regulation (EU) 2020/741 of 25 May 2020, which sets minimum requirements for water quality at European Union level, depending on the use. French regulations have therefore been brought into line with the provisions of this Regulation for crop irrigation and the watering of green spaces, and ANSES issued an opinion on the draft texts. 

Find out more:

• Opinions and reports on the reuse of treated wastewater for irrigating crops, spray watering green spaces and washing roads (2012)
• ANSES opinion on the draft ministerial order relating to the conditions for the production and use of treated wastewater for irrigating crops or green spaces (2023)

Reuse of treated wastewater for other purposes, such as urban uses

Where health conditions are complied with, the Decree of 29 August 2023 allows prefects to authorise the use of treated wastewater for other purposes, such as urban uses (washing roads, for example). This authorisation is only possible subject to compliance with quality requirements set locally and a review of the local project at least every five years.

This same decree defines the conditions under which rainwater collected from inaccessible surfaces may be used for non-domestic purposes, without special authorisation.