All water is recycled and reused as a part of natural water processes such as the hydrologic cycle.

Man-made water recycling, also known as water reclamation or water reuse, centers on using treated wastewater.

Recycling wastewater can extend water supplies, improve water quality, reduce discharge and disposal costs of wastewater, and save energy.

Most recycled water comes from treated municipal wastewater or sewage, though other sources include domestic gray water.

In California, water recycling is a critical component of the state’s efforts to use water supplies more efficiently. [See Aquapedia's entries on wastewater treatment process and gray-water].

The state presently recycles about 714,000 acre-feet of water per year and has the potential to reuse an additional two million acre-feet per year.  Water management officials in the state are also shifting away from construction of new dams and reservoirs, making water recycling increasingly important.

Water Recycling Overview

Cities, farms, and industries are using recycled water as an alternative for a wide variety of not-potable and potable uses (treated drinking water for consumption). Non-potable uses include:

• landscape and crop irrigation
• stream and wetlands enhancement
• industrial processes
• recreational lakes, fountains and decorative ponds
• toilet flushing and gray water applications
• as a barrier to protect groundwater supplies from seawater intrusion
• wetland habitat creation, restoration, and maintenance
• groundwater recharge

Using recycled water for such applications reduces reliance on increasingly scarce and expensive surface water. It can also minimize groundwater overdraft and reduce discharges of treated wastewater into rivers and oceans.

For different uses of water, there are different levels of treatment. The extent of treatment —secondary, tertiary or advanced —is determined by the initial quality of the water, the end-use application and state laws.

However, water recycling is not without drawbacks.

The need for treatment and storage facilities and a delivery system separate from the potable supply involve relatively high costs.

Water quality can be an issue, as well. Recycled water, which generally contains more salt than traditional sources of water,  and can damage salt-sensitive crops, plants or groundwater basins.

Water Recycling Going Forward

In California, home to a booming population and a desert climate in large parts of the state, efficient water use is critical. In the face of such demand and a limited supply, water recycling is increasingly common throughout California. Already, some parts of the state recycled water meets approximately 7 percent of water supply demands.

The California State Legislature also aims increase the use of recycled water by at least 1 million acre feet to 1.5 million acre feet by 2020.