That small water supplies are a weak link for water safety in the Nordic region was already revealed in the forerunning study published in 2017. Between 2010 and 2014, 47 waterborne outbreaks with 57 thousand illnesses were registered in Denmark, Finland, Iceland, Norway and Sweden with more than 80% (39) of the outbreaks occurring in supplies serving less than 5000 people. The population-weighted average faecal contamination (Escherichia coli) incidence rate in the Nordic region was over ten times higher in smaller water supplies (<500 inhabitants) than in larger ones (>5000 inhabitants), see Fig. 1.
The European Union had already recognized a decade ago that small water supplies in Europe are less monitored and much less likely to meet the quality standards of the Drinking Water Directive compared to larger ones e.g., as described in a report on water quality for Europe 2008–2010. Non-compliance related to exceedance of the microbiological criteria for E.coli and enterococci in water supplies serving less than 5000 people for this period was 5-10% in Denmark, 1–5% in Finland and <1% in Sweden, while the remaining Nordic countries did not provide data for this EU study.
In 2020, the then-new EU DWD (EU 2020/2184) introduced four relevant changes from the former (1998) Directive (EU/98/83) exact sampling frequeny for small and very small water supplies; requirement to implement RBA in all regulated systems; fulfilling Goal 6b of the UN’s Sustainable Development Goals (SDGs) ; and requiring access to up-to-date information to the public to increase citizens’ confidence in the water suppled to them.