Mildly Infuriating

Ok, where do you get those 50 people?

There are places that regularly do this. Where do you think they get enough people to visit and/or mail every address? Who works at the post office? Cops? First responders? Utility workers? Social workers? Delivery drivers?

This is not just a failure of imagination, it is trying to pretend this kind of operation doesn't already happen every day right where you live.

Do you have 50 people sitting around on-call 24/7/365 just in case they need to go knock on everyone's door?

Why would they need to?

Are you taking them off of other jobs to go do this? If this happens at 3AM on a holiday weekend, there's probably a pretty good reason those other people are already on the clock, like maybe fixing whatever issue is causing the advisory.

Yes you are taking people off of other jobs to do this. Why would they all be working on the problem that caused the boil notice? Do you think your mailman is cranking on water mains?

Are we relying on volunteers? How are we going to get ahold of them to let them know, let alone guarantee that they're actually going to show up.

If you wanted to use volunteers you would do it by having a group ready to meet up, get trained, and then do these kinds of tasks when needed. You would get their phone numbers in advance and then call around to get together a group. This is how all civil volunteer groups work. Search and rescue. Emergency volunteer firefighters. This is an everyday thing and very basic. Why imply it's impractical?

We gonna mobilize the national guard to do it? How long is that gonna take to get going?

The governor could do that, yes. They mobilize very quickly, they do evacuations for natural disasters. They train for this kind of logistics thing. But sending notice in the mail would be much cheaper.

Maybe we'll just press-gang the first 50 people we can get our hands on to do it. What could possibly go wrong?

"What about [stupid thing]? You're so dumb for thinking the thing I just made up."

But let's say getting the people is a solved problem. How are they getting around? Not every area is easily walkable.

The US is car-dependent. You would use cars. Those owned by the authority, municipalities, owned by USPS, cop cars, etc. How do you think your mail works? Purely pedestrian?

Do we have 50 municipal cars on standby for them to use?

For an area with 55,000 people? Yes you have 50 vehicles that could be used, though you don't need 50 because you can do 2-3 per car if you're doing the door knocking strategy.

And yes most municipal vehicles are "on standby". Tons sit in parking lots all day. Ask your county about their staff vehicles and the reservation process.

Are we going to have additional people driving them around to the needed areas in vans?

Why would they need to?

Are they using their personal vehicles and will need to be compensated for gas and mileage (not to mention probably an insurance nightmare for those people using personal vehicles for non-personal use)

Could be. Depends on exactly how incompetent the water authority is. As we can see, publishing info in the internet equivalent of a dark corner in a broom closet is a strategy they actually went with.

They are liable for this and can opt for as expensive snd dumb or cheap and efficient of a method they'd like.