What societal challenge in the 19th century drove the shift toward industrial, centralized filtration systems?

The proliferation of dense urban populations coupled with rampant waterborne diseases like cholera and typhoid.

The massive population growth associated with the industrial expansion of the 19th century placed unprecedented strain on existing water sources and infrastructure. Crowded urban environments became breeding grounds for severe public health crises, most notably outbreaks of devastating waterborne illnesses such as cholera and typhoid fever. This crisis signaled that localized, household-scale filtration was inadequate for safeguarding entire communities. Consequently, innovation was forced to pivot toward developing large-scale, centralized municipal systems—often involving massive sand and gravel beds—designed to treat the entire public water supply before distribution, fundamentally shifting filtration from a personal comfort to a public health imperative.