Overview of groundwater sources and water-supply systems, and associated microbial pollution, in Finland, Norway and Iceland

Kløve, B.; Kvitsand, Hanne Margrethe Lund; Pitkänen, Tarja; Gunnarsdottir, Maria J.; Gaut, Sylvi; Gardarsson, Sigurdur M.; Rossi, Pekka M.; Miettinen, Ilkka

Overview of groundwater sources and water-supply systems, and associated microbial pollution, in Finland, Norway and Iceland | Aperçu des ressources en eau souterraine et des systèmes d’approvisionnement en eau, et pollution microbienne associée, en Finlande, Norvège et Islande Visión general de las fuentes de agua subterránea y de los sistemas de abastecimiento de agua, y la contaminación microbiana asociada, en Finlandia, Noruega e Islandia 芬兰、挪威和冰岛地下水源、供水系统以及相关微生物污染的回顾 Panorâma das fontes de águas subterrâneas e sistemas de abastecimento de água, e poluição microbiana associada, na Finlândia, Noruega e Islândia

2017

The characteristics of groundwater systems and groundwater contamination in Finland, Norway and Iceland are presented, as they relate to outbreaks of disease. Disparities among the Nordic countries in the approach to providing safe drinking water from groundwater are discussed, and recommendations are given for the future. Groundwater recharge is typically high in autumn or winter months or after snowmelt in the coldest regions. Most inland aquifers are unconfined and therefore vulnerable to pollution, but they are often without much anthropogenic influence and the water quality is good. In coastal zones, previously emplaced marine sediments may confine and protect aquifers to some extent. However, the water quality in these aquifers is highly variable, as the coastal regions are also most influenced by agriculture, sea-water intrusion and urban settlements resulting in challenging conditions for water abstraction and supply. Groundwater is typically extracted from Quaternary deposits for small and medium municipalities, from bedrock for single households, and from surface water for the largest cities, except for Iceland, which relies almost entirely on groundwater for public supply. Managed aquifer recharge, with or without prior water treatment, is widely used in Finland to extend present groundwater resources. Especially at small utilities, groundwater is often supplied without treatment. Despite generally good water quality, microbial contamination has occurred, principally by norovirus and Campylobacter, with larger outbreaks resulting from sewage contamination, cross-connections into drinking water supplies, heavy rainfall events, and ingress of polluted surface water to groundwater.

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