Suspended Ion Exchange (SIX) technology will soon be used to remove PFAS, known as “forever chemicals,” from Tampa’s water, the Tampa Water Department said at a press conference at the David L. Tippin Water Treatment Facility on Monday.
TWD has been working toward implementing SIX technology at DLTWTF since 2018. In January, testing from Carollo Engineers found that SIX removes 50% of naturally occurring organic matter and 30% of PFAS compounds from Tampa’s river water.
“What we’re doing at Tippin is bigger than Tampa alone. It’s raising the bar on how modern water utilities can address emerging contaminants and existing challenges,” said Vincent Hart, executive vice president of Carollo Engineers.
PFAS are man-made chemicals that take a long time to break down. They’re linked to severe health issues and can be found everywhere — from non-stick cookware to rain jackets.
SIX removes organic compounds and PFAS by adding resin beads, which are surrounded by chloride ions, to the water. The chloride ions exchange places with natural organic matter and PFAS that bind to the resin beads, which then enter a cleaning cycle, removing contaminants.
After 8 years, two pilot programs and a third-party review, the project has moved into the design phase. TWD will partner with the Tippin Water team, which includes Carollo Engineers, Garney Construction, Wharton Smith, Inc. and PWNT, the developer of the solution, to design and construct the SIX water treatment facility at DLTWTF.
Hart expects the project will break ground in mid-to-late 2027. The project could cost roughly $200 million, and is scheduled for completion in 2032.
According to water planning manager Sarah Burns, SIX will save the City of Tampa $2 million per year in operational costs by reducing some treatment chemicals currently used. Implementing SIX could also save over $80 million in future facility improvement costs.
TWD’s project will be the first employment of SIX technology in the U.S. and the largest SIX installation globally. Only two other facilities in the world currently employ it: Mayflower Water Works in Plymouth, England, and Andijk III Water Treatment Plant in Andijk, Netherlands. PWNT, which is part of Hart’s team, ran the Andijk plant and knows “the ins and outs” of how to handle the technology, Hart said.
PFAS are not currently regulated, but Tampa’s implementation of SIX coincides with the Environmental Protection Agency’s Maximum Contaminant Levels (MCLs) for two types of PFAS, PFOS and PFOA, going into effect April 2029.
There is discussion of extending the MCLs to 2031, since many utilities were blindsided when the regulations were announced in 2024, Burns said. Tampa Water Department is “pretty far ahead,” but does have an interim PFAS mitigation plan in place if extensions are granted.
