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Treatment Plants

DWP operates several treatment facilities to further our commitment to providing quality services to our customers

The DWP operates several treatment plants and facilities to ensure reliable water delivery and efficient water reclamation services.  Here is a glimpse into the operations at some of these facilities. To learn more about these facilities, sign up for one of our quarterly facility tours

Lester Treatment Plant

photos of the Lester plant

The Lester Treatment Plant treats raw Colorado River water the DWP purchases from Western Municipal Water District. The plant receives water from a 108" diameter water pipeline.

The Lester Treatment Plant treats Total Suspended Solids (TSS) through six filters. TSS is the visible particulate matter and colloidal matter that cause cloudiness. The 5-step process includes:

  • Chemical addition rapid mixing including pre-chlorination
  • Coagulation
  • Flocculation
  • Filtration
  • Post-disinfection

Once the water has been treated, it is stored in a distribution storage tank. All aspects of the plant are automated so that they can be operated either onsite or remotely.

Take a tour - watch a short video tour of this treatment plant:

Lester Treatment plant tour

Temescal Desalter

photos of the desalter

The Temescal Desalter is a reverse osmosis (RO) treatment facility where water is forced one-way through membranes that reject salts. These membranes remove Total Dissolved Solids, or TDS, which are substances dissolved in water such as minerals and salts that are not visible to the naked eye. The Temescal Desalter produces 10 million gallons of product water each day. The DWP blends this water with 5 million gallons per day of groundwater for a total of 15 million gallons per day!

The workhorses of the desalter are the sophisticated membranes that filter the water. Here are some interesting facts about them:

  • The Temescal plant has 1,407 membranes
  • All water is pre-filtered before to avoid damage to the membranes
  • Membranes are cleaned every 6 months to extend their useful life
  • Each membrane costs approximately $400
  • Membranes are typically changed every 5 years
  • The salty concentrate water is discharged to the Inland Empire Brine Line or IEBL and eventually reaches specially equipped treatment plants operated by the Orange County Sanitation District. After treatment, the waste is discharged to the Pacific Ocean.

The Temescal Desalter was one of the first of its kind in the Inland Empire. The DWP received several grants to help construct the $42 million facility. The Temescal Desalter operates 24 hours, 7 days a week. It only shuts down for membrane replacement and maintenance.

Take a tour - watch a short video tour of the Temescal Desalter:

temescsal desalter

Water Reclamation Facilities #1 and #2

Water Reclamation Facility #1 photos

This facility treats sewer discharge to produce reclaimed water using a six-step process.

  • Step 1 – Screenings/major solids removal
    • Large objects are removed, cleaned, and hauled to landfill.
    • A cyclone separator removes grit, dirt, coffee grounds and eggshells to prevent equipment damage. The result is sprayed with sodium hypochlorite to eliminate odors.
  • Step 2 – Primary Clarification
    • Sedimentation basins slow the water's velocity so that particles can settle out and remove floating grease that causes odors.
  • Step 3 – Aeration            
    • Water is oxygenated to sustain reproduction and growth of bacteria (micro-organism mass) that consume the organic wastes.
  • Step 4 – Secondary Clarification
    • Water velocity is slowed down again to allow the micro-organism mass to settle to the bottom and be collected then it is returned to aeration to consume organics again.
  • Step 5 – Filtering
    • Sand filters remove suspended solids making the water clear.
  • Step 6 – Disinfection

Take a tour - watch a short video tour of the Water Reclamation Facilities:

wrf1 & wrf2

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