Balancing the chemical and microbial risks in the disinfection of drinking water supplies in developing countries

Developing countries of the world are alarmed by the focus of the developed countries upon disinfection by-products (DBPs) that are potentially harmful to human health, particularly those due to chlorination. In many economically disadvantaged countries chlorination is currently the only affordable barrier against the transmission of waterborne disease: their only choice is between microbiologically safe water which contains potentially harmful DBPs or drinking water that does not contain DBPs but has the health risks associated with waterborne microbial pathogens. Under such circumstances the microbial safety must take precedence because the associated health risk is far greater than the health risk of DBPs which exceed the norms being established by the developed countries. A number of feasible water treatment alternatives which are in various stages of development are being field tested in Latin America and the Caribbean. Those with the greatest potential to resolve both the microbial and the DBP health risks are described.