Increased information on waterborne outbreaks through efficient notification system enforces actions towards safe drinking water Outi Zacheus and Ilkka T. Miettinen ABSTRACT In 1997, a compulsory notification system for waterborne outbreaks was introduced in Finland. The main aim of this notification is to obtain immediate information on suspected waterborne outbreaks in order to restrict and manage the outbreak promptly. During the past ten years, there have been 67 waterborne outbreaks in Finland, mainly associated with small groundwater supplies or private wells. The number of reported waterborne outbreaks has increased since the launch of the notification system indicating that the threshold limit of outbreak detection has most probably decreased. The number of cases of illness has fulfilled the national health target, which is below 0.01% of the population, but more action is still needed to ensure the production of safe drinking water under all circumstances. Ten years accumulation of knowledge on outbreaks has revealed that a compulsory notification system is an effective tool to gather information on waterborne outbreaks. The system has also increased awareness of possible problems related to the quality of drinking water. This article summarises management and legislative actions and policy measures taken so far in Finland to reduce the number of outbreaks and cases of illness related to them. Outi Zacheus (corresponding author) Ilkka T. Miettinen National Institute for Health and Welfare, PO Box 95, FI-70701 Kuopio, Finland E-mail: outi.zacheus@thl.fi Key words | drinking water, groundwater, management action, microbiological quality, small water supply, waterborne outbreak INTRODUCTION The quality of drinking water produced by small water supplies or private wells is a concern around the world including Europe (Hulsmann ; WHO b). The qual- ity of drinking water from these supplies is not always known and registered, but several reports have shown that the use of drinking water from either small water supplies or private wells can be a source of a waterborne outbreak (Nygård et al. ; Kvitsand & Fiksdal ; Ter Waarbeek et al. ). The concern is notable because the number of small water supplies is high in Europe. A questionnaire- based survey on the implementation of the drinking water directive 98/83/EC has showed that in many European countries more than 90% of water supplies are small serving fewer than 5,000 customers (Hulsmann ). One in ten citizens of the European Union is estimated to receive drinking water from small water supplies. According to a recent survey conducted in 2009 the quality of drinking water produced by these small water supplies is often poor. The results of this survey were presented by the Euro- pean Commission in February 2011 during the meeting of the Committee under the Directive 98/83/EC. The number of small water supplies and private wells is high also in Finland. According to the official record in 1999, the number of water supplies serving at least 50 custo- mers is over 1,300 (Lapinlampi & Raassina ), but the number of smaller water supplies serving fewer than 50 cus- tomers is estimated to be even higher. In addition, around half a million people, mainly in sparsely populated areas, get their drinking water from private wells. Although the drinking water service in Finland is continuously being 763 © IWA Publishing 2011 Journal of Water and Health | 09.4 | 2011 doi: 10.2166/wh.2011.021