MANAGING UNCERTAINTY IN THE PROVISION OF SAFE DRINKING WATER

摘要

Microbiological threats remain the most urgent problem in delivering safe drinking water all over the world with a stubbornly substantial number of deaths that can be directly attributed to this cause. According to WHO, almost 1 billion people lack access to an improved water supply. There are 2 million annual deaths attributable to unsafe water, sanitation and hygiene and more than 50 countries still report cholera to WHO. In addition millions are exposed to unsafe levels of naturally occurring arsenic and fluoride. Many of these problems relate to developing countries but not exclusively since the greatest problems tend to be associated with small resource limited supplies, often in rural areas. Changes to water supply are not always easy to make and can be prohibitively expensive for many supplies where resources are very limited. Frequently, changes lead to more sophisticated systems of treatment that also require a greater level of expertise to manage them. It is not so long ago when the conditions in the cities of Europe and The United States resulted in endemic typhoid and frequent outbreaks of cholera. The answer was to change water supply and sanitation practice; changes which included filtration and eventually the addition of chlorine as a disinfectant. Subsequently chlorination became the most widespread disinfectant used in water supply, including more frequently in maintaining the safety of drinking water at a household level in developing countries where delivery of water may not be to the house or where rainwater collection is practiced.