We provide the water consumed in Tampa Bay

The desalination plant, located in Tampa Bay on Florida's west coast, was ACCIONA's first large-scale international desalination plant.

ACCIONA was awarded the contract to operate and maintain the IDAM for 25 years, as well as to solve the operational problems that the facility has encountered since its start-up.
During three years of intensive work, reconstruction work was carried out to make it fully automatic, old designs were improved and processes and systems were corrected.
It has a capacity of up to 110,000 m3/d and is designed to supply at least 10% of the water consumed in the Tampa Bay region.


  • Location: Tampa, Florida, U.S.A.
  • Procedure: Reverse osmosis
  • Type of contract: EPC and O&M (25 years)
  • Capacity: 108,675 m3/day
  • Population: 724,500 inhabitants

Key figures


inhabitants served


m3 per day


years of EPC + O&M contracts

Technology and innovation

A pre-coat filtering system.

ACCIONA has used a pre-coat filtration system in many facilities, such as the Tampa SWRO (Florida).  The pre-coat filters used by ACCIONA are high efficiency pressure filters for retaining suspended solids. They are particularly effective for solutions that require a high level of quality, such as pre-treatment for desalination by reserve osmosis, solutions with low solid content, with SDIs below 3.


The pre-coat filter can add to the filtration and absorption properties, depending on the type of material used to make the pre-coat. They are also used for processing oils and grease, when using other filter types would be unsuitable.

Sand filter protection

In order to avoid the entry of molluscs and fish that prevent filters from working properly, a biocide product is continuously dosed in conjunction with automatic grilles with 3 millimetre gaps.

Pre-treatment improvements

The distribution of water to the 250 plus sand filters was modified and a second filtration stage added, much finer than the existing filter. The natural resource of finely ground fossilised shells of single cell algae was used. The chemical products dosing was also modified and the entire system was automated.

Improvements to the osmosis racks

All the membranes were replaced, totalling over 10,000, with a new membrane washing system designed and installed with temperature regulation and instruments added

Post-treatment improvements

The water resulting from the osmosis process does not contain minerals. In order to add them and meet supply quality requirements, new equipment for dosing chlorine dioxide and calcium hydroxide were installed

Waste treatment

The solids removed from the water during the treatment are in a very diluted state. In order to reduce transport costs, a thickening and dehydration line was constructed, which produces solids with a 25 % concentration (which can be transported by lorry), and the water is recovered in the desalination plant

Environmental impact

At full capacity, the reverse osmosis process generates around 72 million litres of brine, which is diluted with 5,300 million litres of water used by the neighbouring power plant for cooling, providing a dilution ratio of up to 70:1.

The diluted water then passes through the plant's discharge channel, mixing with more seawater and is returned to Tampa Bay with a salinity level almost equal to the bay's water, meeting every safety requirement.

The major volumes of water that flow close to the Big Bend area help dilute it even further, ensuring that salinity does not build up over the long-term.

MARCH - Tampa Bay Water requested proposals to revamp the plant and operate it long-term

NOVEMBER - The Tampa Bay Water Board of Directors approved agreements with American Water-Pridesa (ACCIONA Agua) to resolve design and construction deficiencies

JANUARY - Large-scale pilot testing began

JUNE - NPDES permit modification application submitted

SEPTEMBER - Design of the new plant completed

DICEMBER - Building permit and public water system permit issued; pilot testing concluded

FEBRUARY - NPDES permit modification issued and first concrete poured for the new plant

SPRING - Plant renovation completed and plant testing period begins

NOVEMBER - Acceptance testing starts

DECEMBER - Acceptance tests passed. The plant starts operating at full capacity. Received US 21,250,000 from SWFWMD after achieving the first funding milestone.

DECEMBER - Achieved second funding milestone of 12 months averaging 12.5 MGD. Received US 42,500,000 from SWFWMD

FEBRERO - Achieved third and fourth funding milestones - 12 months averaging 20 MGD and 4 consecutive months averaging 25 MGD - so received US 21,250,000, totalling US 85,000,000 plus interest from SWFWMD

Awards and recognitions


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