What is Recycled Water?
Treated wastewater (secondary effluent) is sent through filters to produce recycled water. The filtration or tertiary treatment process removes very fine particulate matter from the water using a type of membrane filtration in which hydrostatic pressure forces liquid against a semipermeable membrane. The filtered water is disinfected with sodium hypochlorite (bleach) prior to distribution. Recycled water is used mainly for irrigation of landscaping at parks, schools, the zoo, golf courses, homeowners associations, and retirement homes. Additionally, recycled water is also used at some sites for toilet flushing, dust control, and sidewalk cleaning. The recycled water distribution system uses completely separate piplines from the City's drinking water system and is denoted by purple pipes, purple color-coded irrigation systems, and signage.
History of Recycled Water Project
After several dry years in the late 1970’s, and continued population growth in the City, analysis of the City’s water supply showed that additional water sources were needed. Recycled water was identified as a potential substitute for potable water for irrigation and other uses. The City’s Recycled Water Project was developed in two phases. Phase I was completed in July 1989, and Phase II was completed in May 1991. The total cost of the project was $15,200,000. To fund the project, the City received $7 million in low interest loans from the California State Water Resources Control Board. In October 2015, the City began distributing recycled water from the newly constructed Tertiary Treatment facility. The Tertiary Treatment facility uses ultrafiltration technology to produce high quality recycled water. The total cost of the project was $15 million. A grant was obtained through the Department of Water Resources Integrated Regional Water Management Drought Grant program in the amount of $1,045,222 to offset project costs.
Why Use Recycled Water?
Every gallon of recycled water for irrigation saves a gallon of potable water that can be used in homes and businesses. Recycled water serves an important role in the diversity of the City’s water supplies. Recycled water is used at over 50 sites throughout the City, and the annual demand for recycled water is currently 800 acre feet–approximately 700,000 gallons per day.