if raw sewage water can be filtered &turned into drinking water, why can't the same be done to salt water

Answer 1

There is no place in the world where raw sewage water is being filtered &turned into drinking water that people actually drink. Sewage is treated as well as can be done cheaply and dumped into rivers or oceans. The drinking water is obtained separately, and treated again.

By the way, there are places where sea water is turned into fresh water, like Saudi Arabia, where they have plenty of oil to run the power hungry process and also a real shortage of fresh water in their desert country.

Answer 2

In the practical sense, Sewage is not filtered to make drinking water. wastewater treatment plants remove the solids and also the Oxygen Demand from sewage. Many stages of settling, aerating, and yes, often times final filtering and disinfection make wastewater suitable for discharge to rivers, lakes, ground water, or the ocean. Often, the receiving water is the source water for a drinking water system, which would treat and filter and disinfect the water again before distribution for domestic use. Salt water is desalinated by a process totally unrelated to this.

Answer 3

it can't be filtered, as dissolved NaCl molecules are far far too small for the smallest filter that can be made. Filters can only remove organic particles and microbes above a certain size, usually measured in microns (a micron is a millionth of a meter)

Salt water is heated so it evaporates, the pure H2O condenses and the salt crystals are left behind.

Answer 4

the same IS done routinely, in many parts of the world, in big water desalination plants. Typically in places that are short on water, and close to the sea, such as the Middle East.

Answer 5

once again I've come late to the party... but like the others have said. It can. But the cost is very high and the benefits to cost are prohibitive. There are plans in the works for largescale plants that are more cost effective but they are still years from being built.

Answer 6

It can. It's called desalinization. It's just comparably expensive right now. Theres a link below to an article that explain a little about desalinization.