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Turning wastewater into drinking water through reclamation

Posted: 3:50 PM, Nov 01, 2017
Updated: 2017-11-01 22:12:57Z
Touring Tucson's underground sewer system
Touring Tucson's underground sewer system

Local experts have always highlighted the importance of reclaimed water. In Pima County, reclaimed water is vital, locally generated, and a key component of the county's water resources.

We deal with wastewater every day, whether we use our shower, the bathroom, or dishwasher, but for many of us, it is a mystery where all that wastewater ends up.

How the wastewater is cleaned and turned into safe drinking water is also a mystery.
We toured the Tres Rios Water Reclamation Facility to witness exactly how the process works. "Wastewater comes here, we stabilize it utilize it, disinfect it, put it out as a safe product to the environment," Plant manager Arturo Norzagaray, said.

The facility, which is off of I-10 near Ina Road, operates 24 hours a day, seven days a week and machines process more than 30-million liters of wastewater a day. That equals 131 Olympic sized swimming pools!

"We have redundant equipment, we have three screens, they remove all the large material, anything bigger than three quarters of an inch, they'll take out of the water, anything from logs, bricks, shopping carts - could be about anything anyone can get in a sewer, we pull out of here," Deputy Director of Treatment John Sherlock said.

At Tres Rios, officials agree that water in the southwest is a commodity, so they do anything they can to protect it.

The process can take up to 8 hours. "We have to put out a good product that is going to go back into the drinking water of tomorrow," Norzagaray said.

When the wastewater arrives, it enters the plant through what they call the head works, and then it gets divided up into water and solids. It goes through sewers, pipes, and machines then enter "biological treatment," which removes about 75-80% of the waste out.

The rest happens underground. Our tour took us through a labyrinth of sorts, through many tunnels. "You can see all of the pipes that run through here, electrical baskets and different things that run here and there," Norzagaray explained as we made our way underground.

During this stage, "scum," such as grease, oils, and plastics are removed.

The next part is to deal with the solid waste material, in which the solids are kept for several days in heated and closed tanks. There, the bacteria break down the material, making it smaller, and getting rid of organisms that can cause disease. That material is then transferred through tunnels and sludge pipes for stabilization and thickening before it is created into fertilizer for local cotton farmers to use in Pima County. The plant has been outputting all of their bio-solids for growing cotton since 1983, Norzagaray added.

The final step in the process took us outside, where the water is disinfected to make sure all the viruses are destroyed. After spending almost 8 hours in the facility, the water ends up in another waterfall, where viruses and chlorine are removed. The final product, clean treated water, then ends up in the Santa Cruz River to serve Pima County.

It's a lengthy process that ensures the millions who live in Pima County get good quality water.


Although county workers make sure the process goes smoothly, there are several things you may do that can disrupt the process. Sometimes, you may not even realize you're doing it, flushing certain items can harm the pipes that connect to city sewers and the city sewer system.

Officials of the Pima County Water Reclamation Facility want to remind everyone that a clear drain is a happy drain - please be kind to your toilet and sewer system. Even small packages that say "flushable," can cause expensive problems for the facility.


  • CIGARETTE BUTTS: They're full of incredibly toxic chemicals that just end up in the water supply. Also, think of all the water you're wasting to get rid of ONE tiny butt!
  • CAT LITTER: Cat litter is made from clay and sand, two things that should NEVER be put down a toilet. Not to mention that cat waste contains toxins and parasites that shouldn't be in our water system.
  • FATS, OILS, GREASE: When grease washes down the sink, it sticks to the insides of the pipes that connect your home or business to the city's sewer. It also coats the insides of the city's sewer pipes.
  • BABY WIPES: They don't dissolve in the water company's septic system and can clog the equipment in the local sewage works that aren't designed to handle such "solid" waste.
  • PLASTIC: It doesn't dissolve!
  • PILLS, MEDICATIONS: Medications and supplements should not be flushed or disposed of through the toilet or drain. They should be wrapped and thrown in the trash, brought to your local drug take-back site, or disposed of in accordance with your healthcare facility's guidelines.
  • PAPER TOWELS, RAGS, CLOTH: Even those labeled as flushable don't always dissolve and can cause huge clogs.
  • FEMININE HYGIENE PRODUCTS: As with baby wipes these don't always dissolve the way they were intended and can clog pipes.

The two biggest causes of sewer clogs are “flushable” wipes and FOG (fats, oil and grease). Even the items above labeled "flushable" should not be flushed.

Carlos Herrera is a reporter for Good Morning Tucson on KGUN9-TV. He can be reached via email at . Follow him on Facebook @CarlosHerreraNews and Twitter @KGUNCarlos .