From desalinated water to drinking water

Desalination has become a critical solution for securing drinking water supplies, particularly in water-scarce and coastal regions. Reverse osmosis technology makes it possible to produce extremely pure water at scale, but that purity comes with a challenge in most cases, the water is too pure! Desalinated or demineralized water cannot be distributed as drinking water without further treatment.

By removing almost all dissolved minerals, reverse osmosis produces water with very low buffering capacity. This low mineral water is chemically unstable, prone to pH fluctuations, and potentially corrosive to pipelines, storage tanks, and household plumbing. Without correction, utilities face increased maintenance costs, infrastructure degradation, and difficulties in maintaining compliance with drinking water standards. Remineralization is therefore not an optional finishing step; it is the process that transforms desalinated water into stable, compliant drinking water suitable for long-term distribution.

Why low mineral water needs to be stabilized

Effective remineralization is about much more than simply adding minerals back into the water. It serves three interconnected objectives: restoring essential minerals such as calcium and magnesium for public health, stabilizing pH and alkalinity to prevent corrosive conditions, and improving the water’s taste and overall palatability for consumers. Achieving all three requires a controlled and reliable process, especially in large scale desalination plants operating continuously under varying conditions.

Among the available remineralization technologies, calcite contactors based on calcium carbonate (CaCO₃) and carbon dioxide (CO₂) have become increasingly recognized as a robust and sustainable solution. In these systems, water passes through a calcite bed where controlled CO₂ dosing promotes the dissolution of calcium carbonate. This single reaction naturally increases calcium concentration, alkalinity, and pH stability, providing an intrinsic buffering effect. Compared with lime-based systems, calcite contactors typically offer more stable operation, simpler chemical handling, and a lower overall process risk, advantages that are particularly valuable at scale.

Optimizing remineralization: where performance meets economics

While calcite contactors are a proven technology, their performance and economics are highly dependent on design and operating conditions. Key parameters such as empty bed contact time (EBCT), the ratio of treated water to by-pass flow rate, media characteristics, CO₂ dosing strategy, and local chemical prices all interact to influence both water quality and total treatment cost. Designs that overlook these interactions often result in unnecessary capital expenditure or suboptimal operational efficiency.

This is why a techno-economic approach is essential. Rather than applying generic design rules, Omya combines process performance modelling with cost analysis to evaluate how different design choices impact both compliance and economics. By analyzing various Empty Bed Contact Time (EBCT) scenarios and integrating region-specific pricing for calcium carbonate, carbon dioxide, and alternative reagents, utilities can identify configurations that deliver stable drinking water while remaining economically viable under local market conditions.

Experience shows that two factors consistently dominate both cost and performance: EBCT and regional chemical pricing. Shorter EBCT reduces reactor size and investment but may increase CO₂ consumption, while longer EBCT improves dissolution efficiency at the expense of higher capital cost. The combination of the chemicals used in remineralization, EBCT, and calcite chip size, plays an important role in achieving the target of positive LSI. At the same time, chemical prices vary significantly by region, making local benchmarking a critical part of decision making. Optimization lies in finding the balance point where water quality targets, operational stability, and total cost align.

From analysis to implementation: Omya’s approach to remineralization

From modelling through to implementation, Omya supports utilities with dedicated laboratory capabilities, field experience across Europe, the Middle East, Africa, and Asia, and highly qualified engineers. This end-to-end expertise ensures that remineralization systems are not only technically sound, but also practical to operate and align with long-term operational and sustainability goals.

As global desalination capacity continues to expand, utilities face growing pressure to deliver safe drinking water while controlling costs and reducing environmental impact. Optimized calcite contactor remineralization offers a clear path forward, combining proven technology with informed economic decision-making to turn desalinated water into stable, compliant drinking water, tailored to local conditions and built for the long term.

For deeper insights into proven remineralization technologies, visit our Omyaqua portfolio and see how our tailored solutions support reliable, longterm operation.