An abandoned ship in what used to be the Aral Sea, in Kazakhstan. Irrigation projects have caused it to shrink to 10% of its original size.

Food and Agriculture Organization's estimate for 2025 in Africa: 25 countries are expected to suffer from water shortage or water stress.

Water scarcity is a lack of fresh water. For us, and most land animals, fresh water is drinkable, and sea water is not. This is because sea water has a high salt content, which we and most land animals cannot deal with.

The need is not just for fresh water, but for clean water. That usually means water which is free of harmful bacteria and parasites and general dust and dirt.