Sanitation is the greatest medical milestone of the last century and a half, acccording to a poll carried out by the British Medical Journal.

Sanitation was the clear winner among 15 milestones shortlisted by readers of the journal, including the development of vaccines, which has safeguarded many children's lives, and the invention of the contraceptive pill, which was a contributory factor to significant social change.

The winner was chosen by more than 11,000 members of the public around the world, who were invited to read articles championing each of the 15 contenders by prominent scientists, either in the journal or on the BMJ website. The competition was to mark the relaunch of the BMJ and all the innovations had to have taken place since it was first published in 1840.

Sanitation was the undisputed winner, with 1,795 votes, over antibiotics in second place with 1,642 votes, and anaesthesia which took third place with 1,574.

Johan Mackenbach of Erasmus University Medical Centre in Rotterdam, who championed sanitation, said: "I'm delighted that sanitation is recognised by so many people as such an important milestone. The general lesson, which still holds, is that passive protection against health hazards is often the best way to improve population health."

The heroes of sanitation in this country were John Snow, who showed that cholera was spread by water, and Edwin Chadwick, who came up with the idea of sewage disposal and piping water into homes.

Chadwick was a lawyer and his scheme was based on a wrong concept of the cause of disease. He thought he was trying to eliminate the untimely deaths of male breadwinners through infectious diseases spread through air contaminated by poor drainage in the closely populated urban areas of the industrial revolution.

It took decades for Britain to implement Chadwick's ideas for piped water and flushed sewer systems but in the end they had a big effect on mortality. It is difficult now to calculate the cut in deaths attributable to improved sanitation in the 19th century, but it is possible to see the effects in the developing world wherever clean drinking water and sewerage are introduced. One major review showed deaths and damage in children from diarrhoeal diseases were reduced by about a fifth.

Professor Mackenbach draws three conclusions. First, he says, Chadwick proved you do not have to know all about disease causation to intervene effectively. Second, environmental improvements, such as the provision of clean water, can be more effective than trying to persuade individuals to change their behaviour. Third, interventions targeted at all the people may be more effective than those aimed at particular groups, such as the most deprived.