The main types of water treatment plants are: 1. Drinking water treatment plants, 2. Sewage treatment plants, 3. Industrial water treatment plants, 4. Seawater desalination plants.

A seawater treatment plant, also known as a desalination plant, is a facility that converts seawater into fresh water through desalination technology. Its main technologies include reverse osmosis (RO), multi-stage flash evaporation (MSF) and multi-effect distillation (MED). Reverse osmosis is currently the most common desalination technology. It uses high pressure to force seawater through a semi-permeable membrane, removing salt and other impurities, and ultimately obtaining pure fresh water.

According to statistics, there are currently about 16,500 seawater desalination plants in operation around the world, spread across 185 countries. The plants can produce an estimated 110 million cubic meters of fresh water per day. This means that a considerable amount of seawater is desalinated every day and becomes a freshwater resource that can be used by people.

Sea water desalination is a technology that removes salt from seawater, but the process produces harmful by-products that negatively impact the environment. The main concerns are the discharge of treated brine and the possible contaminants produced during the production process.

The water quality safety issue of desalination plants is an important issue related to public health and life. Through strict technical processes and management measures, desalination plants can ensure that the treated water quality reaches safe drinking water standards and provide the public with safe and reliable drinking water resources.

Solar energy has broad application prospects in seawater desalination. Solar energy can directly drive thermal desalination systems, converting solar energy into thermal energy through solar collectors, providing the required energy to evaporate and condense seawater, thereby achieving desalination.

Five desalination plants built along the country's coastline — in Soreq, Hadera, Ashkelon, Ashdod, and Palmachim — currently operate and two more are under construction. Collectively, these plants are projected to account for 85-90 per cent of Israel's annual water consumption, marking a remarkable turnaround.

The cost of water is a major consideration. The construction and operating costs of seawater desalination plants are high, making the cost of seawater desalination much higher than other sources of water resources, such as groundwater and river water. Secondly, the sea water desalination process may cause harm to marine life.

In large municipal seawater desalination plants, the cost of desalinating one cubic meter of water is typically around $0.50 - $1.00. The cost per liter of water is approximately US$0.0005 - US$0.001.

Seawater desalination technology uses reverse osmosis technology to remove salt and impurities from seawater, thereby converting salt water into fresh water. The process includes steps such as seawater pretreatment, reverse osmosis system operation, freshwater collection and treatment.