Though 1.2 billion people gained access to drinking water from an improved source over the period 1990–2004, the absolute number of people without such access declined by only 118 million, because of population growth. If current trends continue, the unserved population will decrease further by an estimated 150 million by 2015. Despite that improvement, the world will still have over 900 million unserved in 2015, three quarters of whom will be living in rural areas. In sub-Saharan Africa, although access to improved drinking water sources increased by 7% between 1990 and 2004, the actual number of people without access to drinking water from an improved source increased by 60 million.

The current coverage trend indicates that by 2015 the number of unserved people in sub-Saharan Africa will grow by a further 47 million.