It's what the title suggests, simply salt or usually very salty water.
Although at least two thirds of our planet is covered with water, less than 2% of it is drinkable. However, salt water can be made drinkable through desalinization and other filtering or processing.
Desalination plants take in salt water and output pure water and brine, which is still basically salt water but with a higher concentration of salt. You might expect them to output pure water and pure salt, but for various reasons they actually release the salt back out as brine.
When poorer countries need to get water, they use distillation. This is basically purifying water, using large amounts of electricity and money.
the first step is it passes through all the membranes
Its costly,
the plant requires lots of energy to operate
critics believe this will result in an increase in greenhouse gas emissions.
it depends on where you are and how you do it.
global warming affects the sea level and that gives us less water to desalinate and it also effects the sea life so that is more harmful especially with desalination