The Bolivian water minister said on Monday that La Paz wanted to call supplies of clean water a human right in a document to be signed at the meeting this week.
"It's very clear that we all have a right to life and health," Abel Mamani said. "The right to life and right to health without water is contradictory."
South America's poorest country, increasingly vocal on the world stage since the election of Evo Morales as president, is resisting other nations and international bodies at the World Water Forum being held in Mexico City.
A draft of the declaration calls water important to the poor and to people's health, but does not describe it as a human right.
Morales created a water ministry after taking power in January and appointed Mamani, an activist in recent years who was chasing foreign water companies, such as French utility Suez, out of Bolivia.
Mamani said privatisation of water services in Bolivia led to soaring prices that left clean water out of the reach of the poorest people.
"You can't use a thing as important as water, which is synonymous with life, to make money," Mamani said.
"The right to life and right to health without water is contradictory"
Abel Mamani, Bolivian water minister
"We're talking about something that unfortunately is necessary for survival."
The World Water Forum's ruling body is made up of members from governments, international organisations such as the World Bank, scientists and business people.
About 1.1 billion people, mostly in Asia and sub-Saharan Africa, lack easy access to safe drinking water.
Delegates at the meeting have said new ideas and investments are needed to meet a UN goal of halving the number of people without safe drinking water by 2015.
Mamani complained that the entry fee to the forum, at $120 a day, effectively excluded the poor from taking part.
The right to water - World Health Organisation
The right to water (pdf) - United Nations