In a message to a water management conference in Rome on Thursday, Francis lamented that war, corruption and financial interests often get in the way of providing universal access to clean water for all.
He said recognition of access to clean water as a basic human right is "incompatible" with the concept of water as a merchandise to be bought and sold.
The United Nations first recognised the legal right to safe drinking water in 2010.
The UN says poverty, pollution and climate change are depleting water resources globally, with some 884 million people without access to improved sources of drinking water.
The one-day meeting was held at the Pontifical Urbaniana University.
It was organised by the Dicastery for Promoting Intergral Human Development.
The embassy staff from the Holy See of France, Italy, Monaco and the United States were also involved.
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