Bringing Water to a Rolling Boil

spotlight-Sanitation-april-2-2013In many parts of Nepal, while there is no other mechanism to ensure that drinking water is safe, boiling water before drinking is the most effective solution for water purification.

The WHO Guidelines for Drinking-water Quality (WHO,  2011) advised that it is sufficient to inactivate pathogenic  bacteria, viruses and protozoa by bringing water to a rolling boil. Previous editions of WHO guidelines were not so clear about this.  So WASH agencies used to advise people to boil longer, for 5 minutes or so. 

Please update your agency’s guidance and let boiling be just a roll! 

This new WHO guidance note explains that a rolling boil is sufficient to inactivate pathogenic  bacteria, viruses and protozoa.  

After the water has reached a rolling boil, it should be removed from the heat, allowed to cool naturally, without the addition of ice, and protected from post-treatment recontamination during storage. If turbid water needs to be clarified for aesthetic reasons, this should be done before boiling.

WHO Guidelines for drinking-water quality

The World Health Organization (WHO) published three editions of the Guidelines for drinking-water quality in 1983–1984, 1993–1997 and 2004.

This edition of the Guidelines further develops concepts, approaches and information introduced in previous editions, including the comprehensive preventive risk management approach for ensuring drinking-water quality that was introduced in the third edition. Download the full guidelines here -