Over 120 countries voted for the resolution, which was proposed by Bolivia.

Despite abstentions from 41 countries, including the UK, USA and Canada, most states recognised that more than 884 million people lack access to safe drinking water and 2.6 billion have no basic sanitation.

Diarrhoea, caused by lack of sanitation, is now the biggest killer of children under five in Africa. A rights-based approach is critical to ensuring that the billions of people living without sanitation and the millions without safe water get the access that they need.

Loïc Fauchon, president of the World Water Council said: “This right is an essential brick in the wall we want to build against ignorance, injustice, poverty, and thirst.

“Let us etch the right to water in the constitutions, define minimal water allocations for the most deprived persons, impose the compulsory creation of water supply points and of sanitary facilities in each school, everywhere in the world.

“It is through hundreds, and thousands of solutions for water, that the right to water will become reality.”

Kate Norgrove, head of campaigns at UK NGO WaterAid also welcomed the resolution, but expressed regret that the vote was not passed by consensus.

“Abstentions illustrate the continuing lack of priority given to sanitation,” she said, “which is astonishing given that slow progress on sanitation is holding back progress on many of the other Millennium Development Goals.”

Norgrove said WaterAid was looking forward to the continuing work of the Independent Expert, Catarina de Albuquerque, who is due to report to the Human Rights Council on water and sanitation in 2011.

“The hard work starts here,” she said. “Now we need this international agreement translated into action on sanitation and water by governments at the national level.”

Countries voted for the resolution, which was proposed by Bolivia. States recognised that more than 884M people lack access to safe drinking water and 2.6B have no basic sanitation.

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