The quantity of water available at the source must be sufficient to meet various demands and requirements of the design population during the entire design period. Plans should be made to bring water from other sources if the available water is insufficient. The water available at the source must not be toxic, poisonous or in anyway injurious to health. The impurities

The quantity of water available at the source must be sufficient to meet various demands and requirements of the design population during the entire design period. Plans should be made to bring water from other sources if the available water is insufficient.

Hardness is the property that makes water require more soap to produce a foam or lather. The hardness of water is not harmful to human health but can be precipitated by heating so can produce damaging effects in boilers, hot pipes, etc by depositing the material and reducing the water storage and carrying capacity. Absolute soft water on the other hand is not acceptable

Collection of domestic wastewater is best achieved by a full sewerage water drain age system. Unfortunately this method is most expensive and there is relatively few communities in hot climate which afford it. A modern hygienic method of night soil collection is the only realistic alternative. Treatment is required principally to destroy pathogenic agents in sewage or night

The first unit operation generally encountered in wastewater treatment plants is screening. A screen is a device with openings, generally of uniform size, that is used to retain solids found in the influent wastewater to the treatment pant. The principal role of screening is to remove coarse materials (pieces of wood, plastics, rags, papers, leaves, roots etc.) from the