Band 7+: The diagram below shows the process of desalination, in which seawater is converted into drinking water. Summarise the information by selecting and reporting the main features, and make comparisons where relevant. Write at least 150 words.

The diagram illustrates how sea water is purified to be drinkable water through a process called desalination.

Overall, this process involves 7 phases which require the presence of advanced machines such as pretreatment filters, reverse osmosis to ensure that the salt is completely separated.

In the initial stage, water is collected through several pipes. Then the raw water goes through an intake screening process during which impurities and debris are separated. Following this, water is subjected to pretreatment filters, in this stage, microorganisms or small particles are removed.

Once pretreated, it undergoes a reverse osmosis membrane unit for extracting salt and impurities from the water. Next, the freshwater is transferred to post treatment in which it is treated one more time before meeting the drinking standard.Finally, the refined water is stored in a designated supply tank, ready for distribution as drinkable water. Meanwhile, the concentrated seawater by-product returns to the ocean through the outlet.