> I wonder how much human health is impacted by these leaky pipes.
Not much, because the water mains pressure keeps nasty things from entering the pipe.
However, when the system is depressurized due to a power outage or due to running out of water, nasty things can happen (stuff entering the water pipes, oxygen from air bubbles causing rust), and that's why after such events boil-off orders are issued for a few weeks afterwards until it can be reasonably assumed that all pipes have been flushed and all air bubbles have gone.
Not much, because the water mains pressure keeps nasty things from entering the pipe.
However, when the system is depressurized due to a power outage or due to running out of water, nasty things can happen (stuff entering the water pipes, oxygen from air bubbles causing rust), and that's why after such events boil-off orders are issued for a few weeks afterwards until it can be reasonably assumed that all pipes have been flushed and all air bubbles have gone.