Only on ABC-7: Making Rio Grande water safe to drink

It might be hard to believe that the often-dry Rio Grande River is a major source for the Sun City’s drinking water.

But after an ABC-7 viewer questioned why his home’s drinking water source was changed from the aquifers to the river, and whether it was safe, El Paso Water offered ABC-7 a tour of the Robertson/Umberhauer Water Treatment Plant in South El Paso.

“The water comes in here for the first time, and it goes through our screening process,” Ruben Rodriguez, the water supply manager for El Paso Water, told ABC-7 as he pointed to a channel that connected to the Franklin Canal, which runs through the Chihuahuita neighborhood near the U.S./Mexico border.

“Whenever farmers are using the (river) water, that’s when we have that water available to us, as well,” Rodriguez said.

This year, 40 percent of El Paso’s water supply will come from the river. Rodriguez said the city is lucky to have the river to help meet the needs of the community.

“It preserves our aquifers,” Rodriguez said. “It helps us to maintain that for future generations.”

Rodriguez showed ABC-7 the seven processes used to transform river water to drinking water. There are two physical screenings before the water even enters the building: a barrier that stops trash and sediment from coming into the plant; water then moves to grit chambers, where remaining sediment settles to the bottom and is pumped out.

Shortly after, a predisinfectant consisting primarily of chlorine is added to the water in the inflow pump system.

“It will kill most of the bacteria that is in there,” Rodriguez said, adding that the chemicals added meet state and federal safety standards. “Other chemicals added will coalesce the material and settle out in the process.”

Rodriguez told ABC-7 that after the water is predisinfected, there must be “contact time” so the disinfectant can kill any viruses in the water. “The process (lasts) 40 minutes.”

Inside the plant, Rodriguez ushered ABC-7 into a large room with six open pits full of water. He said they were the primary clarifier tanks.

“(It’s a) filtering process, the last polishing process. It removes anything that may still be there,” Rodriguez said. He explained that it is in the primary clarifier tanks that the water’s turbidity is vastly diminished. Turbidity is defined as the cloudiness or haziness of a fluid caused by large numbers of individual particles that are generally invisible to the naked eye.

“This water is filtering through carbon (in the primary clarifier tanks), and its turbidity … by the time it goes through it goes through that filter is a 0.06 NTU (Nephelometric Turbidity Unit),” Rodriguez said. “We start the process at 200 NTU on a normal day. … So, we know the water is safe at that point.”

Rodriguez said the Environmental Protection Agency and the Texas Commission on Environmental Quality set turbidity standards at 0.3 NTU.

Polyorthophosphate, which Rodriguez explained as a compound that keeps the water from corroding a home’s pipes, is added, along with more chlorine. “We add chlorine at the end … so we to ensure that we take care of that last portion of disinfection,” he said.

It takes three to four hours to convert up to 40 million gallons daily at the Robertson/Umberhauer plant into potable water.

“Surface (river) water is a lot more difficult to treat than groundwater,” Rodriguez said. “Surface water obviously has a lot more organics. There’s a lot more sediment in the water. There’s a lot more we have to do.”

When ABC-7 asked Rodriguez about his response to customers who were frustrated by the odor coming from the water after utility crews treated an algae bloom in the river, Rodriguez said, “It’s not unsafe. I mean, it’s aesthetically unpleasing, we do know that, but we try to minimize that as much as possible.

“Water quality is one of our highest priorities,” he added. “We want to make sure our customers know that they’re getting safe water, and clean water, and water that will be here for generations to come.”

Rodriguez said water customers may contact the utility with any concerns. The list of contact information is here.