Water use is influenced by natural cycles, but the main impacts over the coming decades are likely to be due to human activity, notably demographic change and economic growth. Over 90 percent of projected population growth by 2050 (3 billion more people) will be in developing countries, often in regions where water is already scarce. OECD Insights: Water examines the issues impacting the water debate today, namely demography, agriculture, energy, climate change, infrastructure, and investment.