Water enters rivers and lakes through precipitation (rain, snow), surface runoff, groundwater seepage, and contributions from springs and tributaries.

After we use water, it goes through a wastewater treatment process. This process involves removing pollutants and contaminants from the water to make it safe for the environment. The treated water is then typically discharged into rivers, lakes, or oceans. In some cases, treated wastewater may also be reused for irrigation or other non-potable purposes.