Anyone looking down while flying in or out of Austin has likely seen the odd tower with a bowl-shaped top and uneven paint job rising above the Mueller neighborhood.
The landmark puzzled KUT listener Ryan Ellerd Jones, so he asked about it for our ATXplained series.
“What is that half-a-water-tower looking structure off of 51st between Berkman and Manor? Is it some sort of radar?”
Jones, who has lived in Austin most of his life, said he Googled for answers and asked friends and family, but couldn’t come up with any information to explain the structure that towers over the former Mueller Airport.
“My first inclination was [that it was] a half-built water tower,” he said. “The first time I saw it I thought maybe it just lost funding. I don't know. It just looks like they stopped constructing it."
A sign that reads “City of Austin Water Utility” hanging on the fence below the tower is probably the most obvious clue that Jones was on the right track.
According to Dan Pedersen with Austin Water, the tower is the centerpiece of the utility’s Water Reclamation Program, which diverts treated sewage water for uses like irrigation where potable water isn’t necessary. Pedersen managed the design and construction of the tower and today is director of the program.
Most water towers come in standard shapes and sizes that city planners can basically pick out of a catalogue, he said. But, an architect got involved with the 51st Street tower after some vocal, civic-minded Austinites demanded something more unique to suit their city.
“The neighbors wanted a landmark, and so it turned out to be a landmark," Pedersen said. "Interestingly enough, the contractor that we hired to build it was Landmark tanks, out of Fort Worth."
Austin voters funded the tower in a 1998 bond election, but it wasn’t built until 2010. By then, the project cost about $8 million – far more than the initial $3-to-$5 million first floated for the basic infrastructure.
“Yeah, it was a little more costly than most water towers," Pedersen said, "but the reclaimed water system really brings a value to the city, which is not often picked up in a traditional cost analysis."
The 170-foot structure has openings in the roof to collect rainwater and a slanted halo of solar panels on top.
The panels produce "about enough electricity for your typical home in Austin – maybe a little bit more,” Pedersen said.
The water tank, which is the bowl on top, can hold about 2 million gallons. Most of its water is pumped uphill from the Walnut Creek Water Treatment Plant near Martin Luther King Jr. and Ed Bluestein boulevards.
After the water gets to the tower, it feeds a network of commercial businesses in the Mueller area and then goes to bigger consumers like Austin Energy and the City Parks Department. Farther out, it helps water grass at the Hancock Golf Course and the University of Texas.
Kevan Decker, UT water lab supervisor, says in addition to irrigation, the university uses the reclaimed water in two of its seven cooling towers, which help power its campuses and provide air-conditioning. Decker says eventually all the towers will be hooked up to the system, which cuts UT’s utility bill by about $300,000 each year.
“It’s cheaper," he said. "It supplements city water usage - regular old water.”
Reclaimed water is also called “purple water” because the pipes it's pumped through are painted purple to prevent mix-ups with drinking water. The water is clear and odorless, Decker said, and about as “dirty” as seawater.
“It’s very high in chlorine and very high in phosphate," he said. "It’s normally what would be put back in the creek, back to the river: treated sewage water.”
Austin has about 59 miles of purple pipeline. The system has been extending farther south into downtown, with new hookups at Republic Square, the state Capitol complex and the Google office.
At a press conference earlier this month, Travis County Precinct 2 Commissioner Brigid Shea touted the county courthouse’s recent switch to purple water.
“We are swapping out the water source from using treated water for air conditioning ... to using treated wastewater or purple pipe water," she said. "That will save the county and the community 10 million gallons of water a year forever."
Shea said hooking up the courthouse and nearby facilities will save about $136,000 annually. Pedersen estimates the reclaimed water system saves the city $3 million to $4 million per year.
But, Shea said money is only half the reason why using purple water is a good idea.
“I think everyone remembers the 2011 drought when Lake Travis looked like a puddle," she said. "We know we’re going to be hotter and drier in the future. This is just one of the really impactful things we can do to conserve water.”
The city’s conservation efforts seem to be catching on: Pedersen says more than 100 commercial customers have now signed up for reclaimed water service. The system is also expanding in parts of South Austin where a second reclamation tank is slated to be finished in the Montopolis neighborhood Oct. 5. More tanks are planned over the next few decades.