This book is completely based on the research on water treatment. Lots of researches have been conducted on water treatment. However it is still difficult to have safe drinking water around the world. Moreover treatment of wastewater is severe challenging phenomenon. Some developed country conduct the treatment of wastewater before its discharge to environment. But most of developing and undeveloped country still lacks it due to which many water born diseases have been deteriorating the human health and environment. This book is an attempt to present the result of treatment of wastewater before its disposal to the open environment. The treatment of wastewater is carried out by direct electric discharge. The samples of wastewater collected from three different industrial sources were treated by plasma (electric discharge) at the Plasma Laboratory of Kathmandu University. The experimental procedures and its results have been illustrated in concised manner. The results have been elaborated with bar diagram for more convenient study.