How can scientists help improve the supply of potable water?Water from salt water

Sources of fresh water are scarce in some regions of the world. If the area lies near the coast then it is possible to turn seawater into potable water.

The process used to remove the salt is called desalination.

Distillation is used to separate water vapour from the dissolved salt:

• the water is evaporated
• the water vapour is then condensed

In the latest desalination plants, a new technique uses membrane filtration to remove the salt. These use super-fine membranes. The membranes allow water molecules to be forced through, but not the dissolved salts.

Chlorination

Chlorine is effective at killing any microorganisms in water. However, chlorine is toxic so its use does have risks. For this reason the chlorination of water is subject to public regulation and often restricted in many countries.

In some parts of the world, chlorination is still not used. This leads to higher risks of waterborne diseases. In most countries it is believed that the benefits of chlorination outweigh the risks.