Drinking water disinfection

For decades, chlorine has played an important role in water treatment. Chlorine is the most widely applied disinfectant. The advantage of chlorine is that is can easily be produced and that it is relatively cheap. Chlorine effectively kills pathogens. It contributes to the reliability of drinking water produced from surface water. Chlorine tablets are used to disinfect water on locations where no collective drinking water treatment takes place. After the discovery of chlorinated byproducts, the use of alternative disinfectants has increased.

Standards for drinking water disinfection in the EU

The development of drinking water disinfection in Europe has taken the same course as drinking water disinfection in de USA. Most European countries applied drinking water disinfection at the end of the nineteenth century or the beginning of the twentieth century. Chlorine was often used for this purpose. The eldest known application of drinking water disinfection in Europe was the addition of chlorinated bleach in Middelkerke (Belgium). In 1905 the London Metropolitan Water Board started applying drinking water disinfection after researching the disinfection mechanism of chlorine in water purification. This organisation was of the opinion that chlorine disinfection was a suitable alternative for long-term storage of raw water. During storage pathogenic bacteria died out naturally.
In Europe, most drinking water production companies use chlorine as a disinfectant. It is added to water as chlorine gas, calcium hypochlorite or sodium hypochlorite. Ozone is added for flavor and odor control. For drinking water preparation from surface water, chlorine is used as a primary disinfectant in most cases. For groundwater treatment, which is a simpler treatment process, chlorine is often the only proper disinfectant.
Europe uses alternatieve disinfectants for drinking water disinfection, as well (table 1). France, for example, mainly uses ozone. In 1906 one started applying ozone for drinking water disinfection. Italy and Germany use ozone or chlorine dioxide as a primary oxidant and disinfectant. Chlorine is added for residual disinfection. Great Britain is one of few European countries that use chloramines for residual disinfection in the distribution network and for the removal of disinfection byproducts. Finland, Spain and Sweden use chloramines for disinfection occasionally.

Table 1: disinfection applications in the European Union (1998)

Country	Chlorine	Chlorine dioxide	Chloramines	Ozone	UV
Austria	1	3	-	3	3
Belgium (a)	1	3	-	3	3
Denmark	-	-	-	-	-
Finland	1	3	3	3	3
France	2	2	-	2	-
Germany	1	1	-	2	3
Great-Britain	1	3	3	3	3
Greece	1	-	-	-	-
Ireland	1	-	-	3	-
Italy	1	1	-	3	-
Luxembourg	-	-	-	-	-
Holland (b)	2	2	-	1	3
Portugal	1	-	-	-	-
Spain	1	3	2	2	-
Sweden	1	3	2	-	-

Desinfection applications: 1. Most commonly used, 2. Commonly used, 3. Used occasionally
(a) Flamboyant conversion from chlorination to the use of UV light as a disinfectant, namely for groundwater containing a high concentration of trihalomethanes
(b) UV implementation is expected

European Drinking Water Guideline 98/83/EC

In 1998 the European Union accepted the Drinking Water Directive 98/83/EC. This guideline is a framework of quality demands for European drinking water. The appendixes include parameters that must be checked to determine drinking water quality. The countries of the European Union can add their own demands to this guideline.

Biocidal products guideline

In 1998 the Biocidal Products Guideline was implemented. A biocidal product is an active substance or a preparation purpose that contains an active substance, which is ment to kill or deactivate harmful or unwanted microorganisms, by means of biological or chemical resources. Chemical disinfectants for water disinfection are also rated as biocidal products.
When a biocidal product is used incorrectly, it may cause damage to human, animal or plant health, or to the environment. The countries of the European Union determine whether a substance can be used for certain purposes. When a company needs permission to apply a certain biocidal product, this must be requested from the government of its country. A demand must also be sent to the European government. The governments of countries mainly decide whether a substance is permitted. This may cause a substance to be permitted by a certain European country, but restricted by the European Union and vice versa.
 

More information on water disinfection?:

Introduction water disinfection  Necessity water treatment  History of drinking water treatment

What is water disinfection?  Necessity of drinking water disinfection  History of water disinfection  Waterborne diseases  Factors that influence disinfection  Conditions of water disinfection  Regulation drinking water disinfection EU USA

Swimming pool treatment  Swimming pool pollutions  Swimming pool disinfection  Swimming pool disinfection & health

Cooling tower water  Cooling tower water pollutions  Cooling tower water disinfection  Cooling tower water legislation

Chemical disinfectants  Chlorine  Sodium hypochlorite  Chloramines  Chlorine dioxide  Copper silver ionization  Hydrogen peroxide  Bromine  Peroxone  Peracetic acid

Disinfection byproducts  Types of disinfection byproducts  Research on health effects of disinfection byproducts

Chlorinator system