Water is vital to the existence of all living organisms, but this valued resource is increasingly being threatened as human populations grow and demand more water of high quality for domestic purposes. Water can contain substances that are harmful to life.These include metals such as mercury,lead and cadmium,pesticides,organic toxins and radioactive contaminants. However, some of these, particularly bacteria, protists, parasitic worms, fungi, and viruses, can be harmful to humans if present in water used for drinking.Initiatives to better the quality of drinking water at household level have been effective in reducing the occurrence of waterborne diseases.One such system is water purifier system (water disinfection).This book tests the performance evaluation of common water purifiers for increase in improved drinking water supplies reduced household expenditure on water quality, setting some source protection benefits. This book will definitely serve not only as an excellent reference but also as a practical guide for physico-chemical characteristics of water.Book will be useful to environmentalist,teachers,students and common peoples,interested in household common water purifiers