Water is our most important nutrient. Water supply of adequate quantity and quality is a human right. Through its research, Eawag is working to ensure that this right can be guaranteed both in Switzerland and in less privileged regions - a major challenge in view of population growth, climate change and pollutant inputs.
More and more water supply companies are having to treat the water or even shut down wells (Photo: iStock).
A crack in the water tower
In Switzerland, households consume almost 150 litres of drinking water per person per day. 80 per cent of this is obtained from groundwater, the rest from lake water. While lake water usually has to be treated in several stages, most groundwater can be used as drinking water without treatment or with simple treatment. But the supply of drinking water of sufficient quality and quantity can no longer be taken for granted, even in Switzerland’s water tower.
Identifying and reducing pollutant inputs
In intensively farmed regions, nitrate and pesticide residues enter water bodies and groundwater. This poses great challenges for the drinking water suppliers. With its research, Eawag is helping to reveal the extent of the pollution and to develop proposals for improving the situation.
To promote exchange between research, practice and public authorities on these topics, Eawag operates the Platform for Water Quality together with the Association of Swiss Water Protection Experts (VSA) and the Federal Office for the Environment (FOEN), and has also launched the Swiss Groundwater Network CH-GNet.
Expansion of settlement areas and intensive agriculture have a negative impact on water quality (Photo: Markus Bolliger/BAFU).
Eawag is investigating various methods for treating drinking water, here for example with membrane filtration (Photo: Eawag).
Optimising water treatment
In addition to reducing pollutant inputs to water bodies, Eawag is also conducting research into water treatment so the pollutants can be removed as efficiently as possible. This involves optimising existing and researching new treatment technologies, but also potential new pollutants such as nanoplastics.
Even if drinking water of impeccable quality reaches consumers, the building installations on the other hand, harbour new dangers. If the water is heated, legionella can form - bacteria that can cause severe pneumonia, known as Legionnaire's disease. A multidisciplinary research team led by Eawag is investigating how this danger can be contained in the “LeCo” project.
Reusing water
With hot and dry summers becoming more frequent due to climate change, supply bottlenecks are also becoming an issue in the water tower of Switzerland. Eawag is therefore researching the reuse of greywater - effluent from showers, washing machines or dishwashers - which can be treated and used to flush toilets or for irrigation. Because it is not necessary to use drinking water everywhere, as we do today.
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authors => protected'Hammes, F.; Gabrielli, M.; Cavallaro, A.; Eichelberg, A. ; Barigelli, S.; Bigler, M.; Faucher, S. P.; Füchslin,& nbsp;H. P.; Gaia, V.; Gomez-Valero, L.; Grimard-Conea, M .; Haas, C. N.; Hamilton, K. A.; Healy, H. G.; Héchard, Y.; Julian, T.; Kieper, L.; Lauper, U.; Lefeb vre, X.; Mäusezahl, D.; Ortiz, C.; Pereira, A.; Prevost , M.; Quon, H.; Roy, S.; Silva, A. R.; Sylvestre,&n bsp;É.; Tang, L.; Reyes, E. V.; Van Der Wielen, P.  ;W. J. J.; Waak, M.' (642 chars)
title => protected'Foresight 2035: a perspective on the next decade of research on the manageme nt of <em>Legionella </em>spp. in engineered aquatic environments' (141 chars)
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categories => protected'legionella; Legionnaires' disease; legionellosis; building plumbing; opportu nistic pathogens; waterborne disease' (112 chars)
description => protected'The disease burden from <em>Legionella </em>spp. infections has been increas ing in many industrialized countries and, despite decades of scientific adva nces, ranks amongst the highest for waterborne diseases. We review here seve ral key research areas from a multidisciplinary perspective and list critica l research needs to address some of the challenges of <em>Legionella </em>sp p. management in engineered environments. These include: (i) a consideration of Legionella species diversity and cooccurrence, beyond <em>Legionella pne umophila</em> only; (ii) an assessment of their environmental prevalence and clinical relevance, and how that may affect legislation, management, and in tervention prioritization; (iii) a consideration of <em>Legionella </em>spp. sources, their definition and prioritization; (iv) the factors affecting Le gionnaires' disease seasonality, how they link to sources, <em>Legionella </ em>spp. proliferation and ecology, and how these may be affected by climate change; (v) the challenge of saving energy in buildings while controlling <e m>Legionella </em>spp. with high water temperatures and chemical disinfectio n; and (vi) the ecological interactions of <em>Legionella </em>spp. with oth er microbes, and their potential as a biological control strategy. Ultimatel y, we call for increased interdisciplinary collaboration between multiple re search domains, as well as transdisciplinary engagement and collaboration ac ross government, industry, and science as the way toward controlling and red ucing <em>Legionella</em>-derived infections.' (1565 chars)
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authors => protected'Lin, Z.; Ruan, C.; Xia, R.; Liao, J.; Zhu, L.; Wang , D.; Alvarez, P. J. J.; Yu, P.' (132 chars)
title => protected'Bacterium-phage interactions enhance biofilm resilience during membrane filt ration biofouling under oxidative and hydraulic stresses' (132 chars)
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categories => protected'membrane biofouling; oxidative stress; microbial adaptation; phage-host inte ractions; auxiliary metabolic genes; quorum sensing' (127 chars)
description => protected'Microbial interactions on membrane surfaces can facilitate biofilm formation and biofouling, which poses a significant challenge for pressure-driven mem brane filtration systems. This multiomics study investigates the adaptive re sponses of bacterium-phage interactions under varying oxidative and hydrauli c stress during membrane backwashing and their biological contributions to b iofouling. Oxidative and hydraulic stress distinctly shaped bacteria and pha ge diversity and community composition. Under moderate oxidative backwashing (300 ppm of NaClO), diversity was maintained, with increased antioxidant en zyme activities, extracellular polymeric substance (EPS) production, and quo rum sensing (QS) signaling, promoting bacterial resilience and biofilm forma tion. In contrast, excessive oxidative stress (600 ppm of NaClO) reduced bac teria and phage diversity, disrupted antioxidant responses, and increased mi crobial sensitivity. Hydraulic stress predominantly influenced viral diversi ty and co-occurrence network topology, favoring the expansion of broad host- range phages and lysogenic lifestyles under combined stresses. Phage-bacteri um interaction analyses highlighted phages' adaptive preferences for hosts w ith high network centrality and broad ecological niches, which enhanced micr obial interactions and resilience. Transcriptomic profiling demonstrated the early enrichment of genes associated with energy metabolism, ROS detoxifica tion, and biofilm formation, followed by stabilization as biofilms matured. Phage-encoded auxiliary metabolic genes were involved in DNA repair, QS, and EPS biosynthesis, contributing to microbial adaptation through oxidative st ress resistance and biofilm stabilization. Overall, these findings provide m echanistic insights into biofouling dynamics and highlight the need to optim ize chlorine dosing to prevent suboptimal levels of microbial adaptation and biofouling.' (1912 chars)
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authors => protected'Ra, J.; Huang, K.; Mohn, J.; Hofstetter, T. B.; Muc k, E.; von Gunten, U.' (107 chars)
title => protected'Characterization of organic nitrogen by chlorination, ozonation, and stable isotope analysis of nitrate' (103 chars)
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categories => protected'dissolved organic matter; amines; ozonation; chlorination; nitrate; nitrogen isotopes' (85 chars)
description => protected'During oxidation, nitrogenous species in dissolved organic matter (DOM) are critical in the formation of nitrogenous, potentially toxic disinfection byp roducts, but their chemical identity remains poorly understood. Here, we dev eloped three complementary approaches to identify and quantify reactive amin es in model compounds and DOM, including aliphatic primary and secondary ami nes, aryl-type primary amines, amino acids, and terminal peptidic amino grou ps. With the chloramine formation assay, the total reactive amines were quan tified for the main subgroups. An assay with continuous ozonation quantified three types of reactive amines based on nitrate formation rate constants (k <sub>NO<sub>3</sub>-</sub>): k<sub>NO<sub>3</sub>-</sub> < 0.1 M<sup>-1</ sup> s<sup>-1</sup> for secondary and aliphatic primary amines; k<sub>NO<sub >3</sub>-</sub> = 0.9-1.9 M<sup>-1</sup> s<sup>-1</sup> for aryl-type primar y amines; k<sub>NO<sub>3</sub>-</sub> = 15-110 M<sup>-1</sup> s<sup>-1</sup> for amino acids and peptidic amino groups. The analysis of <sup>15</sup>N/< sup>14</sup>N ratios of nitrate helped to distinguish reactive amines based on <sup>15</sup>N enrichment factors (ϵ<sub>N</sub>): aliphatic (or aryl-ty pe) primary amines (ϵ<sub>N</sub>:-9 to -3‰), and amino acids and peptidi c amino groups (ϵ<sub>N</sub>:-28 to -19‰). Overall, 23-27% of the organi c nitrogen in DOM isolates comprises oxidant-reactive amines, with 5-6% seco ndary amines, 10-14% aliphatic primary amines, 4% aryl-type primary amines, 1-4% amino acids, and 0-2% peptidic amino groups. Based on the quantitative characterization of amine moieties in DOM, which are possible precursors of N-DBPs, the formation potential of N-DBPs upon oxidative water treatment was estimated.' (1759 chars)
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Foresight 2035: a perspective on the next decade of research on the management of Legionella spp. in engineered aquatic environments
The disease burden from Legionella spp. infections has been increasing in many industrialized countries and, despite decades of scientific advances, ranks amongst the highest for waterborne diseases. We review here several key research areas from a multidisciplinary perspective and list critical research needs to address some of the challenges of Legionella spp. management in engineered environments. These include: (i) a consideration of Legionella species diversity and cooccurrence, beyond Legionella pneumophila only; (ii) an assessment of their environmental prevalence and clinical relevance, and how that may affect legislation, management, and intervention prioritization; (iii) a consideration of Legionella spp. sources, their definition and prioritization; (iv) the factors affecting Legionnaires' disease seasonality, how they link to sources, Legionella spp. proliferation and ecology, and how these may be affected by climate change; (v) the challenge of saving energy in buildings while controlling Legionella spp. with high water temperatures and chemical disinfection; and (vi) the ecological interactions of Legionella spp. with other microbes, and their potential as a biological control strategy. Ultimately, we call for increased interdisciplinary collaboration between multiple research domains, as well as transdisciplinary engagement and collaboration across government, industry, and science as the way toward controlling and reducing Legionella-derived infections.
Hammes, F.; Gabrielli, M.; Cavallaro, A.; Eichelberg, A.; Barigelli, S.; Bigler, M.; Faucher, S. P.; Füchslin, H. P.; Gaia, V.; Gomez-Valero, L.; Grimard-Conea, M.; Haas, C. N.; Hamilton, K. A.; Healy, H. G.; Héchard, Y.; Julian, T.; Kieper, L.; Lauper, U.; Lefebvre, X.; Mäusezahl, D.; Ortiz, C.; Pereira, A.; Prevost, M.; Quon, H.; Roy, S.; Silva, A. R.; Sylvestre, É.; Tang, L.; Reyes, E. V.; Van Der Wielen, P. W. J. J.; Waak, M. (2025) Foresight 2035: a perspective on the next decade of research on the management of Legionella spp. in engineered aquatic environments, FEMS Microbiology Reviews, 49(2025), fuaf022 (18 pp.), doi:10.1093/femsre/fuaf022, Institutional Repository
Bacterium-phage interactions enhance biofilm resilience during membrane filtration biofouling under oxidative and hydraulic stresses
Microbial interactions on membrane surfaces can facilitate biofilm formation and biofouling, which poses a significant challenge for pressure-driven membrane filtration systems. This multiomics study investigates the adaptive responses of bacterium-phage interactions under varying oxidative and hydraulic stress during membrane backwashing and their biological contributions to biofouling. Oxidative and hydraulic stress distinctly shaped bacteria and phage diversity and community composition. Under moderate oxidative backwashing (300 ppm of NaClO), diversity was maintained, with increased antioxidant enzyme activities, extracellular polymeric substance (EPS) production, and quorum sensing (QS) signaling, promoting bacterial resilience and biofilm formation. In contrast, excessive oxidative stress (600 ppm of NaClO) reduced bacteria and phage diversity, disrupted antioxidant responses, and increased microbial sensitivity. Hydraulic stress predominantly influenced viral diversity and co-occurrence network topology, favoring the expansion of broad host-range phages and lysogenic lifestyles under combined stresses. Phage-bacterium interaction analyses highlighted phages' adaptive preferences for hosts with high network centrality and broad ecological niches, which enhanced microbial interactions and resilience. Transcriptomic profiling demonstrated the early enrichment of genes associated with energy metabolism, ROS detoxification, and biofilm formation, followed by stabilization as biofilms matured. Phage-encoded auxiliary metabolic genes were involved in DNA repair, QS, and EPS biosynthesis, contributing to microbial adaptation through oxidative stress resistance and biofilm stabilization. Overall, these findings provide mechanistic insights into biofouling dynamics and highlight the need to optimize chlorine dosing to prevent suboptimal levels of microbial adaptation and biofouling.
Lin, Z.; Ruan, C.; Xia, R.; Liao, J.; Zhu, L.; Wang, D.; Alvarez, P. J. J.; Yu, P. (2025) Bacterium-phage interactions enhance biofilm resilience during membrane filtration biofouling under oxidative and hydraulic stresses, Environmental Science and Technology, 59(17), 8614-8628, doi:10.1021/acs.est.5c00490, Institutional Repository
Characterization of organic nitrogen by chlorination, ozonation, and stable isotope analysis of nitrate
During oxidation, nitrogenous species in dissolved organic matter (DOM) are critical in the formation of nitrogenous, potentially toxic disinfection byproducts, but their chemical identity remains poorly understood. Here, we developed three complementary approaches to identify and quantify reactive amines in model compounds and DOM, including aliphatic primary and secondary amines, aryl-type primary amines, amino acids, and terminal peptidic amino groups. With the chloramine formation assay, the total reactive amines were quantified for the main subgroups. An assay with continuous ozonation quantified three types of reactive amines based on nitrate formation rate constants (kNO3-): kNO3- < 0.1 M-1 s-1 for secondary and aliphatic primary amines; kNO3- = 0.9-1.9 M-1 s-1 for aryl-type primary amines; kNO3- = 15-110 M-1 s-1 for amino acids and peptidic amino groups. The analysis of 15N/14N ratios of nitrate helped to distinguish reactive amines based on 15N enrichment factors (ϵN): aliphatic (or aryl-type) primary amines (ϵN:-9 to -3‰), and amino acids and peptidic amino groups (ϵN:-28 to -19‰). Overall, 23-27% of the organic nitrogen in DOM isolates comprises oxidant-reactive amines, with 5-6% secondary amines, 10-14% aliphatic primary amines, 4% aryl-type primary amines, 1-4% amino acids, and 0-2% peptidic amino groups. Based on the quantitative characterization of amine moieties in DOM, which are possible precursors of N-DBPs, the formation potential of N-DBPs upon oxidative water treatment was estimated.
Ra, J.; Huang, K.; Mohn, J.; Hofstetter, T. B.; Muck, E.; von Gunten, U. (2025) Characterization of organic nitrogen by chlorination, ozonation, and stable isotope analysis of nitrate, Environmental Science and Technology, 59(26), 13481-13493, doi:10.1021/acs.est.5c01034, Institutional Repository
