Recycled Water

Recycled water is the end product of sewage treatment that mirrors and accelerates the natural water cycle. Just as the earth takes moisture from the oceans and other sources and cycles it back to the headwaters, IRWD’s recycled water process removes contaminants and returns a clean resource. The treatment process takes about 16-18 hours from the time the sewage enters the treatment plant until the finished product is disinfected and ready for distribution throughout the service area.

At the recycling plants, technology amplifies the natural disinfection process. Gravity settles out particles. Microorganisms dissolve organic matter. Advanced filtration and UV light deactivate pathogens. Once the water meets stringent quality standards, we deliver it to recycled water customers through more than 500 miles of purple pipes.

Sewage from the local community is collected and treated to tertiary standards at the Michelson Water Recycling Plant in Irvine and the Los Alisos Water Recycling Plant in Lake Forest.

IRWD’s recycled water is not for drinking or for other uses inside your home. But it is a key component of our water efficiency program, representing 28% of the District’s total water supply. IRWD produces and distributes tertiary treated recycled water, also known as Title 22 water. Title 22 water is used throughout the IRWD service area primarily for landscape and agricultural irrigation. About 80% of the public and commercial irrigated landscape in our service area — including community association property, parks, medians, golf courses and schools — is watered with recycled water. Recycled water is also treated for agricultural use, including edible root crops, where the water comes in contact with the edible portion of the crop. It also is used for toilet-flushing in dual-plumbed buildings, cooling towers in commercial buildings, dust control on construction sites and in industrial processes such as concrete production and composting. Each day, we deliver about 25 million gallons of recycled water to more than 6,000 metered customer connections. Every gallon of recycled water used for these purposes saves a gallon of drinking water.

Yes. A large body of laws, regulations and statewide policies govern how recycled water is defined, what it can be used for and under what conditions it can be used in California. Title 22 of the California Code of Regulations describes the treatment requirements for recycled water as well as the approved uses based on the level of treatment. Also included in Title 22 are the use area requirements, which describe restrictions on the use of recycled water and the requirement to notify the public by posting signs indicating a site uses recycled water. Title 17 of the California Code of Regulations describes the backflow devices required at a site when recycled water is being used to maintain a clear separation between recycled water and drinking water. IRWD also extensively monitors, tests and reports on the recycled water we produce and distribute.

The IRWD Water Quality department samples the recycled water system every week. While state regulations require IRWD to monitor the quality of recycled water as it leaves the recycling treatment plant, sampling within the distribution system is not required by any regulatory agency. IRWD provides that additional testing voluntarily for the benefit of our customers and to maintain internal standards. Twelve distribution sites, three supplemental irrigation wells and four recycled-water storage reservoirs are tested on a monthly or more frequent basis.

Recycled water is delivered through a distribution system that is completely separate from the drinking water infrastructure. This isolated system uses a purple pipe to keep these valuable sources of water distinguishable and make the recycled water system easily identifiable.

IRWD pioneered the use of purple piping, which is now the international symbol for recycled water. Learn more about the origins of the purple pipe.

Recycled water is not available for use on individual properties unless they are estate-sized lots and the water is used exclusively for outside irrigation.

Storage capacity is vital to a recycled water system. IRWD has 16 recycled water storage facilities. That includes four open-air seasonal-storage reservoirs — Rattlesnake, San Joaquin, Syphon, and Sand Canyon — with a combined storage capacity of 1.6 billion gallons.

Recycled water is highly regulated by the state, and approved uses differ depending on the level of treatment applied. At IRWD, sewage undergoes primary, secondary and tertiary treatment at our two water recycling treatment plants.

• Primary treatment: This is the stage where large solids are removed.
• Secondary treatment: At this stage, bacteria are used to remove approximately 90% to 95% of the remaining solids.
• Tertiary treatment: IRWD uses two types of tertiary treatment.
  • In traditional tertiary treatment, filtration removes any remaining solids. After filtration, this water is treated with a disinfectant, such as chlorine, to destroy bacteria, viruses and other pathogens.
  • A more refined tertiary treatment process uses a combination of membrane bioreactor filtration and ultraviolet light disinfection. This new technology produces a more purified water and reduces the need for traditional disinfection chemicals like chlorine.
• Advanced tertiary treatment: This process uses filtration or reverse osmosis to duplicate and accelerate nature’s own purifying system. This advanced treatment produces recycled water so pure that it can be used for groundwater recharge, where it ultimately works its way back into the drinking water cycle. Locally, the Orange County Water District is producing and using advanced treated recycled water from its Groundwater Replenishment System to supplement water supplies in the Orange County Groundwater Basin.