There is no municipal water system in the world that would've maintained pressure. Seriously, I've done the math.

The real issue with those fires was the unfathomably fast growth rate and the gigantic wilderness-urban interface.

Municipal water supplies are (correctly) designed to put out house fires. A few at a time. They are not designed to put out thousands of house fires in high wind.

Also: California's early warning system did work correctly -- IIRC the fire was detected when it was 10 acres. Within 60 minutes, the fire was 300 acres. 3 hours later it was 1200 acres.

The issue was explosive growth.