One data oddity that I learned about when working for the city government was that fire hydrants are broken up into their own bounded zones and maintained, at the time (around 2016) not very well, by different Detroit Fire Department (DFD) engine or ladder companies.
When the effort began in earnest to assess the status of every fire hydrant, Detroit was already the busiest fire department in the country. News reports claimed the city was giving an overly low estimate for the number of hydrants not working. In 2015, journalist Steve Neavling surveyed 15% of the city’s 30,000 hydrants and found 279 broken.
Now this city maintains this dashboard to stay up to date on fire hydrant status across the city.