Wastewater may contain pathogenic microorganisms and/or chemicals that are a risk for human health. Consequently it must be collected and treated before it can be discharged into the natural environment. In this context, ANSES provides support to the authorities in order to assess the health risks associated with sensitive uses (swimming, shellfish farming) located downstream of sewage discharges, it issues Opinions on projects to build sewage plants or on the discharges originating from them, and it produces expert appraisals (upon request by the supervisory authorities) on the effectiveness of non-mains wastewater treatment systems.

In order to prevent the contamination of water intended for human consumption, it is indispensable to take all necessary measures to prevent health risks in water from its source up to the consumer's tap. This means it is essential to ensure the safety of materials and objects which come into contact with water while it is being produced, treated and distributed as well as the safety and effectiveness of products and processes used for its treatment. In this context, ANSES is responsible for evaluating some of these materials or products, for drawing up guidelines for their evaluation and for providing the government with scientific and technical support for drafting corresponding regulations.