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Finding solutions to issues of drinking water safety is a significant component in activities aimed at public health protection. In accordance with sanitary-epidemiological requirements, drinking water, in particular, should be harmless as regards its chemical composition and have favorable organoleptic properties. It is especially vital to identify risk factors for public health associated with drinking water quality. Supplying high-quality drinking water to population is a relevant problem associated, among other things, with use of new materials and reagents. The major challenge posed by their hygienic assessment is a potential growth in human health risks caused by consuming tap drinking water contaminated with migrating organic compounds. Although each of them has been detected in low concentrations, they can cause adverse chronic health outcomes. The Threshold of Toxicological Concern (TTC) is a powerful tool of risk assessment. It is based on identifying a threshold value of effects produced on human health by chemicals for which no hygienic standards have been developed so far. Below such a threshold, there is very low (95 %) likelihood of a health risk being higher than its acceptable levels. An idea of some exposure levels unable to cause adverse health outcomes is embedded in establishing maximum permissible levels (MPLs) for chemicals with known toxicological profiles. The TTC enlarges this concept by assuming that the minimum value can be identified for many chemicals based on their composition even if there is no comprehensive database on their toxicity. The TTC can be used for evaluating up-to-date materials applied in drinking water supply in order to detect risks for human health caused by consumption of drinking water that had contacts with them. Such risk assessment relies on the results of examining water extracts and involves identifying priority chemicals for their further investigation and control.

Nature-based solutions (NBS) are increasingly being promoted as a means to address societal and environmental challenges, especially flood risk reduction. In the context of rapidly urbanizing catchments, NBS can take part of the development of sustainable cities, either by conserving peri-urban ecosystems from urban sprawl or by developing green infrastructure in the cities. Both can provide a wide range of co-benefits (e.g., climate regulation, air quality regulation), but also generate some negative effects (e.g., mobility issues, unsafety, allergens). We develop and implement a Discrete Choice Experiment survey to analyse people's perception of co-benefits and negative effects, and associated preferences for the two types of NBS at a catchment scale. The results obtained from 400 households living in a French Mediterranean catchment highlight that people associate numerous co-benefits to NBS, but also negative effects. Our estimations reveal that resident households are ready to contribute large amounts through a tax increase for the development of NBS (from 140 to 180 EUR/year, on average). There is however a strong heterogeneity of preferences at the catchment scale influenced by income, location of the respondent along an urban–rural gradient, and perception of the importance of ecosystem services. These differences may reflect urban environmental inequalities at the catchment scale, which are important to take into account in order to avoid distributive inequalities. [ABSTRACT FROM AUTHOR]