(Guess what, it's all more complicated.)
I was at a meeting at former workplace this pm because just because I am no longer professionally associated with [particular archive], I am still widely considered A Nexpert in the matter.
So anyway, I was at this meeting, and something set me thinking about the Broad Street Pump.
And how this gets boiled down into a metaphor about removing the handle of the pump as being the dramatic and appropriate action to stop [Bad Thing].
Incidentally we note from that account that John Snow did not himself go and dramatically wrench the handle off the pump but pursued proper channels, take that, mavericks!
But what it's actually about is:
a) meticulous gathering and mapping of data to identify the problem.
b) beyond the emergency intervention: how about we do something to prevent cholera getting into the water-supply, huh?
But people do love the dramatic iconic story. And while I doubt John Snow is exactly a household name, we do note that he gets a pub named after him, as well as there being memorials to the pump itself. Whereas Sir Joseph Bazalgette, who did a whole lot more to provide sanitation for London, doesn't, though he does have a memorial on the Victoria Embankment.