Water management is the activity of planning, developing, distributing and managing the optimum use of water resources under defined water policies and regulations. It may mean or encompass:

Management of water treatment of drinking water, industrial water, sewage or wastewater, rain water, aquatic ecosystems

• management of water resources
• management of irrigation
• management of the water table
• management of the water infrastructure

As water is an essential resource for any creature and the entirety of human social and economic activities, special emphasis must be laid on sustainability and profitability within the water management schemes. Sustainable water management means to limit resource spending to a renewable or replaceable degree meanwhile profitability is closely related to the infrastructure management. An average of eighty percent of the costs of any water management activity is originated by the infrastructure and independent from the transported volumes. Therefore the infrastructure management not only plays a key part for every water utility, it is also decisive for the overall efficiency of any water management policy.

http://en.wikipedia.org/wiki/Water_management