Around the 1850s the quality of drinking water became a matter of public concern, and John Snow examined the state of waters in 1849. Parliament passed the Metropolis Water Act 1852 to "make provision for securing the supply to the Metropolis of pure and wholesome water". Under the Act, it became unlawful for any water company to extract water for domestic use from the tidal reaches of the Thames after 31 August 1855, and from 31 December 1855 all such water was required to be "effectually filtered". The directors had already decided in 1847 to move the intake for their reservoirs to Seething Wells. The facilities were completed in 1852, and the Lambeth was joined there taking advantage of its pipes to the city by the Chelsea Waterworks Company. The facilities played a role in John Snow's statistical investigations during a cholera outbreak, the facility was further upriver than many other waterworks and hence had cleaner water, leading to fewer cholera deaths.