Earth is a literal "water planet," with oceans covering about 71% of its surface. Looking at this blue planet from afar, its abundance of water is enviable. However, reality is harsh—freshwater resources account for only 2.5% of the total water volume, and most of that is "sealed" within the glaciers of the Antarctic and Arctic. The freshwater that humans can actually directly utilize is less than 0.3% of the total.

Globally, approximately 2.1 billion people lack safely managed drinking water, and about 3.6 billion face seasonal water shortages. This number continues to rise.

On one side is the vast ocean, on the other is an urgent freshwater crisis. What is the solution?

The answer may lie within the reverse osmosis (RO) membrane—a "magical" membrane as thin as a cicada's wing that is turning seawater into freshwater.

 I. Reverse Osmosis: From "Seagull Inspiration" to a 60-Year Technological Leap

The inspiration for this technology came from seagulls.

In the 1950s, American scientists accidentally discovered an interesting phenomenon: a seagull would sip a large mouthful of seawater on the ocean surface, and spit out a small mouthful a few seconds later. Land animals that breathe with lungs cannot drink high-salt seawater at all—so how did seagulls do it? Dissection revealed that seagulls have a sophisticated membrane inside their bodies. It pressurizes and filters the ingested seawater, allowing water molecules to pass through and convert into freshwater, while the concentrated salt is spat out. This was the initial concept of reverse osmosis.

In 1953, the University of Florida applied this principle to desalination equipment. In 1960, the US federal government put it into practical use. By 2025, reverse osmosis technology accounted for 70.54% of China's desalination project capacity, making it the undisputed mainstream technology. In 2025, the national desalination capacity reached 3.077 million tons per day, an increase of 86.4% compared to 2020.

Just today (June 8), the latest data shows that China's daily seawater desalination capacity has surpassed 3 million tons, equivalent to the daily domestic water consumption of 15 million people.

 II. The Truth of the "Magic": An Extremely Fine Sieve

The pore size of a reverse osmosis membrane is only 0.0001 micrometers (or 0.1 nanometers), equivalent to one-millionth the width of a human hair. Bacteria and viruses, which are 5,000 times larger, stand no chance of passing through.

The working principle is straightforward:

1. Seawater is pressurized by high-pressure pumps and pushed toward the semipermeable membrane.

2. Under pressure, water molecules are "squeezed" through the pores to the other side.

3. Salts, heavy metal ions, bacteria, and other impurities are completely intercepted and discharged with the concentrated brine.

A single membrane can turn salty, bitter seawater into sweet, fresh water; calling it a "magician" is no exaggeration.

 III. Behind the Numbers: How Many People Rely on "Magic" for Fresh Water?

Global desalination is accelerating. Estimates show that in 2025, the total global desalination capacity reached 68.31 million tons per day. In the Middle East and many island nations and regions, desalinated water has become the primary source of drinking water.

As for the widely discussed issue of energy consumption, technology continues to advance. Take the Rabigh Phase 4 Desalination Project in Saudi Arabia, constructed by SEPCOIII (Shandong Electric Power Construction Third Company), as an example: the measured electricity consumption per ton of water is only 2.712 kWh/m³, breaking the record for the lowest power consumption among desalination projects globally. When integrating the supporting photovoltaic power generation, the comprehensive power consumption per ton of water drops to 2.659 kWh/m³. This means the power required to produce one ton of fresh water is less than what a household air conditioner consumes in a single hour—making it cheaper than ever.

 IV. China's Power: From Follower to Technology Exporter

Notably, China's desalination industry has progressed from meeting domestic demands to exporting technology and equipment.

According to the Director of the Institute of Seawater Desalination and Multipurpose Utilization, Ministry of Natural Resources (China), China's desalination industry has achieved a leap from independent innovation to international development. The performance of domestic reverse osmosis membranes is now basically on par with foreign equivalents. They are widely applied in large-scale desalination projects in Tianjin, Shandong, and other regions, and are gradually entering the global market. In 2025, the 300,000 tons/day Oran desalination project in Algeria, constructed by a Chinese enterprise, was completed and put into operation. This is currently the largest international desalination project independently designed and supplied with core process packages by a Chinese company.

From imitation to independence, and import to export—China's "membrane magic" is going global.

 Postscript

Today is the 18th UN World Oceans Day, with this year's theme being "Reimagine: Beyond the World We Know, A New Relationship with Our Ocean."

The ocean is not just about catches of fish and scenic views; it is also the hope for solving the freshwater dilemma. The reverse osmosis membrane is not literal magic, but a gift bestowed upon humanity by technology. It has transformed "extracting water from the sea"—once an ancient revelation from seagulls—into a practical solution serving hundreds of millions of people.

On World Oceans Day, we salute the deep blue and cheer for our "magicians."