I don’t really understand the thought behind the question. In the sense of legality? Obviously. In the sense of someone saying something? Obviously. In the sense that people have free will? No. The people that work at water facilities are typically technically government employees. If all of them suddenly went rogue would you count that as “the government doing it”? Because they wouldn’t be acting in line with the government, but they’re still “the government.”

So, no, but actually yes, but actually no.

It’s like saying “what’s actually preventing a secret service member from shooting the president?” Nothing? Everything? How do you answer?

is that a hypothetical?

when there’s lead in US drinking water the government just ignores it if it’s in a poor neighborhood

A very fundamental part of that is the amount of moving parts. Every person in the chain that is required for the thing to happen, has to either support the thing or otherwise follow through.

This very concept is what has saved us from nuclear apocalypse so far. Very literally so.

I mean… why do that?

If the government want to kill people in a country where they can get away with it they’ll just send armed men to shoot them.

Poisoning water supply is something the joker would do in a comic book, but on reality it won’t make a lot of sense for any big city. Going there and shooting people is probably much more effective, less expensive and let you with a not-poisoned city to settle with your own people.

How many people go days without drinking tap water?

A function economy 😂. Jk

But being realistic to your answer, it’s possible to be done, but everyone involved would have to be in on it, assuming you wanna get away with it. The US has extremely strict and aware water safety protocols. It would take just 1 whistleblower to takedown this operation.

Nope.

It already happens. Look at things like pipeline leaks poisoning the water supply for certain native groups. There’s obviously protests against such projects that will inevitably lead to said poisoning, people get arrested for protesting, and then they do the project anyways.

No.

But…

The adage that “the dose makes the poison” is working in your favor here. A large city supply delivers millions of liters of water per day; by the time you dilute your poison into millions of liters of water you’ll either be adding absurd amounts of poison (someone is going to notice massive line of tanker trucks queued up outside the treatment plant), or you are dealing with large - but not unweildly - volumes of something so horrendously toxic that it’s still deadly when diluted that much. There are very few substances that toxic, and someone is going to notice if you start procuring hundreds of liters of botulism toxin or Vx because at that point you are dealing with outlawed chemical warfare agents

Racial / cultural supremacists wouldn’t want to kill anyone of their preferred (usually their own) group, and certainly not a significant number of them. They’d basically have to gerrymander the water supply to arrange things so that only those they want to be poisoned actually get poisoned.

That’s 1) expensive and 2) someone’s going to notice.

It would be far easier, and cheaper to go full genocide and start shooting.

In one case, active in the world right now, the “undesirables” live in one area, and rather than poison the water, the supremacists have simply cut it off. They’ve also implemented the “start shooting” strategy.

I wish them all a crippling attack of conscience, and if not that, the inability to distinguish who they want to shoot from who they don’t want to shoot.

Lots of people drink bottled water, soda, beer, or other drinks not immediately connected to the water supply. Furthermore, poisons are unlikely to remain undetected long enough to kill the entire population. While a strong dose of a deadly poison like cyanide can kill in minutes it’s likely to be detected quickly due to how rapidly its effects begin to show up.

A slower-acting, accumulating poison like dimethylmercury could potentially kill more people because its effects don’t show up immediately. On the other hand, the delayed effects of the poison would provide the victims a chance to retaliate against the poisoners.

Either way, it’s a very crude and unfocused attack against a population which is unlikely to achieve any political aim besides wanton destruction and outrage.

Unsure why you’re getting downvoted (this is “No Stupid Questions”, after all), but I’ll give my 5 cents:

Reason 1:
The people is essentially the reason why a government has power. Without the people (and their support), the government governs a whole lot of nothing, and they will be forced to do labour themselves.

Reason 2:
Poisoning the water is not very accurate, and may lead to both the death of many whom already are supportive of the government (which will create distrust), and people only getting sick depending on the amount they drink (the dose makes the poison).

Reason 3:
Despite a population having a lot of dissidents, these people still work and contribute to society in some ways. It has to get pretty bad before it will be “worth it” to remove them from society.

Reason 4:
Even if it’s so bad that you’re looking at an open revolt against the government, poisoning the water will only really yield MAD, which is usually undesirable.

Ultimately, it’s unlikely desirable for any government to do this, as there are better ways (for the government). However, there have been some attempts at genocide through water supplies before, so it’s not completely unheard of. Check out Project Coast.

If you live in an open and transparent society: there will be an investigation and there is a high chance they will find out. You’ll be expected to take care of the mess with disaster relief for the survivors. Also about 40% of the people did vote for you. Also even the ones who did not vote for you still pays tax.

If you live in a dictatorship: police brutality is cheaper and is a bit more selective in it’s targeting.

The chance of them pulling it off with nobody noticing or saying anything is very low, it’s not a one person operation. Then depending on the speed of the poison it would become obvious that there’s something in the water very quickly and people would stop drinking it.

The international backlash would be pretty severe.