Short answers, pulled from the story.
Sextus Julius Frontinus received his appointment as Water Commissioner in the year 96 AD. Emperor Nerva placed him in charge of Rome's entire water supply system at that time.
Frontinus conducted a meticulous survey by calculating the cross-sectional area of pipes or channels without considering water velocity. He investigated apparent discrepancies between expected output and actual delivery rates to identify unauthorized pipe insertions.
Frontinus identified unscrupulous individuals diverting supply without official approval from authorities and sought to curb this illegal activity through strict legal measures against offenders. Lead pipe inscriptions bearing owner names existed to prevent such theft but were often ignored before enforcement became central to his strategy.
Poggio Bracciolini recovered Frontinus' manuscript from the library at Monte Cassino in 1425. This tireless humanist made details about construction and maintenance available once more for Renaissance Rome.
Charles E. Bennett later translated the work into English for broader audiences. Modern understanding of Roman engineering owes much to this rediscovery effort following the initial recovery by Poggio Bracciolini.