Effects of Overpopulation

Around the world, as populations grow, deficiencies in available freshwater supplies are starting to take their toll on already fragile economies, particularly those in the Middle East and North Africa (MENA), where Tony Allan of SOAS in London insists "water demand began to exceed supply in the early 1970s for the region. Some countries have faced deficits since the 1950s".

Each person needs to have one cubic metre (1000 litres) of good quality water to drink each year in order to be considered water sufficient. The amount they require for domestic use depends on the technological level at which they live, for example someone living in rural Africa can get by with 4 cubic metres per year, whilst someone in Europe uses about 100 cubic metres per year. These numbers are small, however in comparison to the amount of water needed to produce the food an individual consumes - and where that food is produced has a lot to do with how much water is needed to produce it. An example for you: Wheat grown in temperate latitudes requires about 1m of water per kg of crop produced, most of it sourced from rainfall; wheat grown in drier climates like the MENA region requires 3 to 5 m of water per kg of crop produced and 99.9% of it is sourced through irrigation and is extracted from rivers and aquifers.

The water required to produce these crops is known as virtual water. Meat products require even more virtual water to produce, because in addition to the water the animals consume, they are more often than not fed on cereals, which themselves have a virtual water content.