Sewage in particular is a severe hazard. Worldwide, polluted water is estimated to affect the health of about 1200 million people and contribute to the death of 15 million children under five every year. Sewage is not the only cause of water pollution. Intensive use of pesticides and fertilisers has increased the level of nitrates in water. This can lead to brain damage and even death among children.
Industrial waste is also a significant polluter - giving rise to contamination with heavy metals.
In some cases, solvents from spills travelled 10km from the source of pollution. Water shortage increases social inequity. In regions such as Gujurat in India, where groundwater levels have dropped considerably, poor farmers cannot sink boreholes to the necessary depths to extract water. Wealthier farmers can benefit by moving inland to buy up more land. In regions like Africa, uneven water distribution is clearly a problem.