This information sheet sets out the general principles of
disinfection of water supplies. Disinfection is a regulatory
requirement and is essential for the protection of public health
from waterborne disease. Disinfection is always carried out on
public water supplies in the UK to protect public health, by
killing or inactivating harmful microorganisms, including
bacteria and viruses, which may be present in drinking water.
Worldwide, many thousands of people continue to die each year
from waterborne diseases. Sickness and diarrhoea and diseases
including cholera and typhoid are spread by drinking water which
is contaminated with human excrement. Disinfection of surface
water is carried out by a two stage process of physical removal
of pathogens followed by inactivation with an oxidising agent.
For water stored in underground aquifers the first stage is
carried out by filtering through the ground. There are several
ways of disinfecting water supplies, and the main methods are
listed below. - Physical removal