The majority of people on Earth will face severe water shortages within a generation or two if pollution and waste continues unabated, scientists warned at a conference in Bonn Friday.

The conference sought to assess the evidence of man’s impact on freshwater resources, which constitute only 2.5 percent of the total volume of water on Earth.

Currently, an estimated third of the world’s seven million people has limited access to adequate fresh water, according to conference delegates.

“In the short span of one or two generations, the majority of the nine billion people on Earth will be living under the handicap of severe pressure on fresh water,” said the declaration.

Two-thirds of major river deltas are sinking due to groundwater extraction, and tens of thousands of large dams are distorting natural river flows on which ecosystems have depended for millennia.

Much damage is being done by river pollution from sewer drainage or agricultural fertiliser and pesticide use.