This study was done in an attempt to reduce the percentage of losses in water treatment plants and networks by reducing its possible causes. Study Design: There are many causes for losses in water treatment plants and networks like water lost in water treatment plants due to washing filters and reservoirs, and water lost in networks due to the lack of maintenance or failure to renew ageing systems, illegal connection, metering errors, or accounting errors. Methodology: Data were collected for Damietta governorate, Egypt. The data collected include types of water treatment plants, capacity, water sold, losses for each water treatment plants and for networks losses, materials and diameters of pipes.