The history of international water treaties dates as far back as 2500 BC, when the two Sumerian city-states of Lagash and Umma crafted an agreement ending a water dispute along the Tigris River.
There are more than 3600 international water treaties dating from 805 AD to 1984 AD.
The UN Convention on the Law of the Non-navigational Uses of International Watercourses was adopted May 21, 1997 after 27 years of development. The Global Convention sets out the basis rights and obligations between States relating to the management of international watercourses.
While the ten-year anniversary of the Watercourses Convention passed in May 2007, only 16 nations have ratified the Convention. For the Convention to enter into force, 35 are needed.
The primary substantive rule of international law is that States must utilize their international watercourses in an equitable and reasonable way.
In the 20th century, only seven minor skirmishes took place between nations over shared water resources while over 145 treaties were signed during the same period of time.
Source: UNESCO Water Portal, July 2007