Population Projections

Design of water supply and sanitation scheme is based on the projected population of a particular city, estimated for the design period. Any underestimated value will make system inadequate for the purpose intended; similarly overestimated value will make it costly. Change in the population of the city over the years occurs, and the system should be designed taking read more

Design Period

The design period is not the same as the life expectancy. The design period is the length of time it is estimated that the facility will be able to meet the demand, that is, the design capacity. The life expectancy of a facility or piece of equipment is determined by wear and tear. The complete water supply project read more


Disinfection is an important step in ensuring that water is safe to drink. Water systems add disinfectants to destroy microorganisms that can cause disease in humans. Disinfection kills or inactivates disease-causing organisms in a water supply and must provide a 99.9 percent inactivation of Giardia lamblia cysts and enteric viruses to protect health. There are two read more

Drinking Water Contaminants

Drinking water is derived from two basic sources: surface waters, such as rivers and reservoirs, and groundwater. All water contains natural contaminants, particularly inorganic contaminants that arise from the geological strata through which the water flows and, to a varying extent, anthropogenic pollution by both microorganisms and chemicals. In general, groundwater is less vulnerable to read more