Bulk Water Transfer & Desalination

Historical accounts describe a besieged Spanish garrison constructing a distillation apparatus to produce fresh water. Technical details are unknown, but the episode is among the earliest recorded practical applications of desalination under duress. It illustrates that pre-industrial desalination was an emergency expedient rather than a water supply method.

Interest in desalination grew in the seventeenth century, with Bacon and Raleigh discussing water purification methods and Hawkins reporting that he supplied his crew with fresh water distilled from seawater at sea. Maritime need for drinking water on long voyages was the main driver of early desalination practice. This interest led directly to the first patents for desalination apparatus.

Patents were granted in 1675 to William Walcot and in 1683 to Robert Fitzgerald and associates, marking the first formal intellectual property in desalination. Neither invention entered widespread service because the technology could not be scaled. No major improvement to the basic distillation process followed until the end of the eighteenth century.

When the frigate Protector was sold to Denmark and renamed Hussaren, its onboard distillation equipment was studied and recorded. Thomas Jefferson later compiled earlier heat-based desalination methods and circulated practical guidance for maritime use. Such documentation helped diffuse shipboard desalination practice between navies.

From the beginning of the nineteenth century the spread of the steam engine and advances in thermodynamics transformed desalination methods. Demand for pure boiler feedwater, combined with colonial expansion into arid regions, created a market for larger plants. More efficient multiple-effect evaporators were introduced, reusing heat across several stages.

Normandy's design became widely used, especially in maritime applications, because it was simple to build and operate. It was the first desalination technology to achieve broad adoption and was later installed in land-based plants. Its diffusion marked the shift from experiment to deployable capability.

These were among the first land-based desalination installations, supplying garrisons in locations without adequate fresh water. Their adoption showed that military logistics were an early driver of fixed desalination capacity. Land-based plants became more frequent in the second half of the nineteenth century.

The plant supplied fresh water for British troops on the Red Sea coast, using multiple-effect distillation to reuse heat across six stages. It demonstrated the colonial military application of large thermal desalination. Such installations established the engineering precedents for twentieth-century multi-stage flash plants.

The office was created to promote research and development in desalination after the Second World War. Its work contributed to the construction of distillation and electrodialysis plants and encouraged international cooperation in the field. It represents the first major state programme dedicated to building national desalination capability.

Research at Californian universities and by chemical companies developed large pilot RO systems during the late 1960s and early 1970s. By this period RO had emerged as a promising alternative to thermal desalination. Industrial membrane manufacture became a prerequisite for national desalination capability.

The plant followed a prolonged regional drought and was the first industrial-scale desalination facility in the country. It marked the transition of post-war thermal desalination research into municipal-scale operation. Thermal methods such as multi-stage flash dominated this generation of plants.

The facility was the first commercial application of membrane-based desalination, in which pressure forces saline water through a semi-permeable membrane that retains dissolved salts. It opened the path to RO displacing thermal distillation. Brackish water was easier to treat than seawater, which followed a decade later.

Seawater desalination energy intensity fell by a factor of ten between 1970 and 2018, with reverse osmosis membranes achieving under 2 kWh per cubic metre against 16 kWh per cubic metre in the 1970s. This efficiency gain is the main reason desalination became economically viable at scale. Scope for further reduction is now limited by thermodynamics.

The first seawater RO facility began operating in 1975, extending membrane desalination from brackish to full-strength seawater. Since that year costs fell from about US$1.10 per cubic metre in 2000 to roughly US$0.50 today. RO subsequently became the dominant global desalination technology because of its scalability and energy performance.

Global desalination capacity reached 99 million cubic metres per day in 2023, up from 27 million in 2003, with the market valued at $20 billion and projected to double by 2032. Thousands of plants operate worldwide, concentrated in the Middle East. Reverse osmosis accounts for most of the growth.

NIOT began studying low-temperature thermal desalination in 2004 and opened its first plant in 2005 at Kavaratti in the Lakshadweep islands, with a capacity of 100,000 litres per day at a capital cost of INR 50 million. The process exploits temperature differences in deep ocean water. It gave India an indigenous desalination technology suited to small island territories.

The 2005 study was positive about desalination for affluent coastal areas but concluded it could not serve poor, inland or high-altitude places with the biggest water problems. It calculated that lifting water 2,000 m or transporting it over 1,600 km costs as much as desalinating it. This defined the geographic limit of desalination as a substitute for bulk water transfer.

Perth commissioned a reverse osmosis seawater desalination plant in 2006, followed by the Kwinana Desalination Plant in 2007 providing nearly 140,000 cubic metres of clean water per day. These were among the first large municipal RO plants in a developed temperate city. They established desalination as drought insurance for Australian cities.

The cancellation followed controversy about costs and environmental impact, notably brine discharge. Texas has over 600 km of coastline and could become a major desalination hub, but the issue remains politically contested. The case shows regulatory and public opposition as a binding constraint on new capacity.

The plant reported desalination costs of RMB 2 per cubic metre, powered by waste heat, well below prevailing global costs. It showed the economics of coupling desalination to industrial or power-plant heat rejection. China thereby set a new low-cost benchmark for manufactured water.

The 2024 results demonstrated separation of salts by thermophoresis, and in 2025 the same process was shown through a Burgers cascade previously used to enhance thermodiffusive separation in gases. With the same device footprint as the 2024 single-channel version, concentration drops and recovery rates improved. The work explores a non-membrane, non-thermal-distillation route.

Recent assessments report that brine discharged from desalination plants now exceeds the volume of fresh water produced. Energy demand for Middle Eastern desalination is expected to double by 2030, and in 2023 desalination consumed nearly half the region's residential sector energy. These findings frame the environmental ceiling on desalination expansion.

By 2023 Israel was deploying desalination not only for agriculture and human consumption but to top up a natural freshwater body. This represented a novel use of manufactured water for environmental restoration. It demonstrated desalination as a tool of national hydrological management.

The device combined multiple stages of ion concentration polarisation with a single electrodialysis stage, removing dissolved salts and suspended solids without filters. It pointed towards portable, off-grid desalination for emergency and remote use. Such units bypass the fouling problems of membrane systems.

The hybrid renewable facility reduced operating expenses by around 40 per cent compared with grid-powered desalination following its 2019 deployment. It is cited as evidence that renewable-coupled desalination can be cheaper as well as cleaner. Renewable desalination is estimated to lower carbon emissions by up to 80 per cent against conventional methods.

Researchers proposed in 2017 that extensive reliance on desalinated water, which lacks naturally occurring minerals, might contribute to population-level iodine deficiency in Israel. The finding raised public health questions about manufactured water as a primary supply. It pointed to remineralisation as a design consideration.

Since 2015 the Carlsbad plant has produced 190,000 cubic metres of drinking water daily, displacing Tampa Bay as the largest US facility. It followed nearly a decade of permitting and cost escalation. It remains the flagship of American municipal desalination.

The Dutch company commissioned an example plant for Gulhi in the Maldives. It illustrated the use of low-grade heat for small-island water supply. Such modular systems extend desalination to communities too small for conventional plants.

By 2014 the four large Israeli plants were desalinating water at less than US$0.40 per cubic metre, among the lowest costs achieved anywhere. Singapore had reached US$0.49 per cubic metre as of 2006. These benchmarks showed desalination could compete with conventional supply in coastal settings.

CETO commissioned wave-powered desalination at Garden Island in Western Australia in 2013 and in Perth in 2015. Oneka subsequently installed comparable systems in Chile, Florida, California and the Caribbean. These projects demonstrated desalination driven directly by marine renewable energy.

Melbourne began using the Wonthaggi desalination plant in late 2011 to raise low reservoir levels. It was the largest such facility in Australia. The project reflected a wave of Australian drought-driven desalination investment.

The process uses solar or other thermal heat to drive an ionic current that removes sodium and chlorine ions through ion-exchange membranes. It can be activated by low-grade heat below 70 °C, potentially requiring no active heating. It was one of several attempts to decouple desalination from electricity supply.

Siemens claimed a process applying electric fields that desalinated a cubic metre of water using only about 1.5 kWh, far below prevailing energy intensity. A demonstration plant was operating in Singapore as of 2012. Electrochemical approaches remained experimental alternatives to reverse osmosis.

The Tampa Bay reverse osmosis facility began producing 95,000 cubic metres of drinking water per day and remained the largest in the United States until 2015. It demonstrated municipal-scale RO in North America. US desalination costs were around US$0.81 per cubic metre.

Approval in November 2007 cleared the way for a plant north of San Diego designed to produce 190,000 cubic metres of drinking water per day, enough for about 100,000 homes. By June 2012 the projected cost of the water had risen to $1.888 per cubic metre. The long permitting and cost escalation illustrated the regulatory burden on US desalination.

The floating plant had a capacity of one million litres per day, scaling up the Kavaratti concept. A smaller plant followed in 2009 at the North Chennai Thermal Power Station to demonstrate LTTD where power plant cooling water is available. These projects explored coupling desalination to thermal generation.