Edwin Chadwick was the first government official to claim that:

poor living conditions caused poor health;
it was the government's responsibility to do something about it.

He produced a report in 1842 which argued that poor living conditions led to poor health and that this cost the taxpayer more. He made four recommendations for the government:

Chadwick's 4 key points

Supply clean drinking water;
Remove sewage;
Clean the streets;
Appoint a medical officer in each district to enforce these rules.

His work led to the 1848 Public Health Act. This encouraged local councils to do these things but it didn't force them.

His work eventually led to the Second Public Health Act which finally enforced his four key ideas. And he had a great comb-over.

John Snow

John Snow was a doctor who proved that cholera was spread through infected water in 1854. This was before Germ Theory and most people still believed that disease was caused by miasma

During the cholera outbreak in London in 1854, he carried out detailed research, plotting the number of deaths on a map. He found that those that had drunk water from the pump on Broad Street became ill. He persuaded the authorities to remove the handle of the Broad Street pump and the cholera outbreak then stopped.

However, Snow was unable to prove how dirty water spread cholera and his ideas were slow to be accepted.

GCSE Health and the People AQA

Edwin Chadwick