How does water pollution and the unequal distribution of water impact irrigation trade industry and drinking water in Northern Africa?

When industries along major rivers such as the Nile River or the Congo River dump their factory wastes into the water, all that pollution is carried downstream. Then, because there are few if any water purification systems, the people who live downstream get all that pollution in their drinking water. If the water isn't distributed properly, then the farmers who need to irrigate their crops won't get to get as much water to their crops. The crops will then die, causing people to starve. Hope this helps!