Around the world, 1 in 5 people have access to clean water, and half of the globe do not have access to sanitation. In the 20th century, half of the worlds wetlands were wiped out due to economic development.  There has also been a rapid decline in surface and groundwater quality. This is a major health threat to humans and natural values.  These statistic scratch the surface of the scarcity issue that the world is facing. 

 

As far as usage goes, the main source of human withdrawals of water comes from something called Blue Water.  Blue Water is renewable surface water runoff and groundwater recharge.  Almost 70% of water withdrawn goes to agricultural use, 20% to industrial, and 10% to municipal. Irrigated areas can run the risk of becoming waterlogged and build up salt concentrations that can make the soil infertile.  By the late 1980's, 20% of the worlds irrigated areas suffered salt build-up. Lack of regulation incentivizes farmers not to conserve groundwater, so they use it up. Of Industrial and Municipal use, 90% of water used is returned as wastewater, and thus has to go through major cleanups before it can be reused.  

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Believe it or not, some of the worlds largest rivers don't even reach the sea.  This is due to the increased water usage from communities along the rivers and depletes the rivers of their reserves.  Some countries consume more water than is being renewed by nature, and as population grows, this will only worsen if nothing changes.