Addressing Water Availability and Quality Challenges on Sanibel Water
The Sanibel-Captiva Islands face significant challenges regarding the availability and quality of potable water. With a single source of drinking water, the Island Water Association’s Reverse Osmosis (RO) Treatment Plant, which treats and distributes 5.99 million gallons daily, the community must continuously adapt to changing demands and environmental pressures. This article explores how the Island Water Association meets the freshwater needs of its residents while optimizing operational efficiency.
The Unique Water Source of Sanibel-Captiva Islands
The Sanibel-Captiva Islands rely exclusively on the Island Water Association for their potable water supply. This non-profit, member-owned facility draws water from 15 wells drilled into the Hawthorne and Suwannee aquifers. Utilizing advanced FilmTec™ RO technology, Island Water transforms brackish, high-salinity water into a clean, drought-resistant drinking water source for its population of approximately 6,700 residents. Due to seasonal tourism, the island’s population can swell to around 14,600, as visitors flock to enjoy the islands’ natural beauty, including 15 miles of pristine beaches, 230 species of birds, 25 miles of bike paths, excellent fishing opportunities, and a traffic-free environment.
The Importance of Freshwater Supply
Chris Krupick, the water plant operator for Island Water, emphasizes the critical role of their facility: “We’re the only source of fresh water on the island. If we can’t make water, there’s potentially 15,000 people that can’t have fresh water to drink, bathe, or do their daily operations. That’s a huge issue for the general public.” This statement underscores the importance of reliable water production, especially during peak tourist seasons when demand surges.
Seasonal Demand Fluctuations
The demand for potable water on Sanibel-Captiva Islands peaks during the tourist season, particularly in March and April. During this time, swimming pools need to be filled, lawns and gardens must be watered, and three golf courses require irrigation. Brandon Henke, the assistant chief operator for Island Water, notes that water demand is typically highest in the early morning hours. “Standard demand during the day and into the early evening is about 1,500 gallons per minute. By 4:00 or 5:00 a.m., it can reach as high as 10,000 gallons per minute.”
Technological Innovations in Water Treatment
To address the seasonal and cyclical demands for water, Island Water began exploring FilmTec RO technology shortly after its introduction in the 1980s. Over the years, the collaboration between DuPont Water Solutions and Island Water has focused on optimizing processes and enhancing energy efficiency. This partnership involves careful monitoring of data collected directly from Island Water’s RO systems.
Originally, the RO membranes operated at pressures of around 300 PSI. With the installation of FilmTec Eco membranes, the system now operates between 150-200 PSI, effectively halving both the pressure and energy required to produce the same volume of water while improving quality.
Pretreatment Processes
Before water enters the RO system, it undergoes several pretreatment processes. An antiscalant is used to keep salts and metals in solution, preventing precipitation on the membrane surfaces. This is followed by filtration through polypropylene melt-blown cartridge filters to remove solids. The water is then pumped into the RO system, which consists of six trains, each equipped with 120 ultrathin spiral-wound FilmTec membrane modules.
As a result of these processes, approximately 80% of the brackish feed water is recovered as high-quality potable water. Each RO train produces an average of 500 gallons of drinking water per minute, with the capacity to generate up to 600 gallons per minute. The purified water is subsequently pumped into a clear well, where it is disinfected using chlorine gas to maintain a residual concentration of 1.6 parts per million (ppm) throughout the 101.5-mile distribution system.
Distribution and Storage
From the clear well, potable water is pumped into two on-site storage tanks, each with a capacity of 5 million gallons, before entering the distribution system. This efficient process ensures that the community has access to safe drinking water at all times.
Recognition for Sustainable Practices
Island Water has established itself as a leader in sustainable RO desalination practices, receiving over 30 awards for its innovative water treatment systems. Notably, it has been honored twice with the Florida Department of Environmental Protection’s Operations Excellence Award for communities of its size. These accolades reflect the facility’s commitment to providing high-quality water while minimizing environmental impact.
Collaboration and Continuous Improvement
The long-standing partnership between Island Water and Water Solutions has fostered innovation and adaptability. “Over the 30-plus years working with [Water Solutions], we’ve been able to test new technologies for them, and in turn, they helped us tailor the membranes to our needs exactly,” Henke stated. This collaborative approach has significantly enhanced the efficiency and effectiveness of the water treatment process.
Community Engagement and Awareness
The Sanibel-Captiva community is increasingly aware of the challenges posed by water scarcity and the importance of sustainable water management. Educational initiatives and community outreach programs aim to inform residents and visitors about the significance of conserving water and supporting local water initiatives. Engaging the community in discussions about water availability fosters a sense of shared responsibility and encourages proactive measures to protect this vital resource.
Future Challenges and Opportunities
As climate change continues to impact weather patterns and freshwater availability, the Sanibel-Captiva Islands must remain vigilant in their water management strategies. Rising groundwater salinity, population growth, and stringent environmental standards will continue to challenge municipal water utilities. However, with a proven track record of innovation and collaboration, Island Water is well-positioned to adapt to these challenges and ensure a sustainable water supply for future generations.
Conclusion
Addressing water availability and quality challenges on Sanibel-Captiva Islands requires a multifaceted approach that combines advanced technology, community engagement, and sustainable practices. The Island Water Association’s commitment to providing high-quality potable water through its Reverse Osmosis Treatment Plant exemplifies how innovation and collaboration can meet the growing demands of the community. As the islands continue to face environmental pressures, the lessons learned and successes achieved in water management will serve as a model for other communities striving to secure their freshwater resources.
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Reference
1.On – Island Water Quality
2.Sanibel Canal System
https://chnep.wateratlas.usf.edu/waterbodies/bays/9000390/sanibel-canal-system
3.Addressing Water Availability &Quality Challenges on Sanibel-Captiva Islands
