Sydney's Kurnell desalination plant has been turned on for the first time in seven years

Sydney's Kurnell desalination plant has been turned on for the first time in seven years, after dam levels dropped below 60 per cent capacity. The New South Wales government hopes drinkable water will be delivered to Sydney's water supply by May or June. But what is desalination, and how effective could it be in protecting Australia from future droughts?