I think it's covered under that "right to life" section of the Constitution. Deliberately poisoning people through their water supply seems like a sure-fire way to deny the right to life of your citizens.

As the other poster mentions, "Life, liberty and the pursuit of happiness" is not from the Constitution but from the Declaration of Independence. As much as it might be part of American civic lore, the Declaration of Independence is not legally binding, it is a product from two whole legal regimes before our current one was founded.

It hasn't counted when it's "accidental" - eg: pretty much all of the US uranium leach well mining resulted in tainted water in a "yeah we know, but don't care" process.

Also radioactive tailings dam collapses and hard rock mining consequences:

On Poisoned Ground

  The largest accidental release of radioactivity in the United States did not occur in 1979 at Three-Mile Island. That very same year a collapsing dam released a flood of radioactive debris into the Navajo Nation.

'We didn't know we were poisoning ourselves': the deadly legacy of the US uranium boom

  Tsosie was one of thousands of Navajos who took jobs in the mines, starting in the 1940s. They worked without masks or ventilation to disperse the lethal radon gas, and they were never told the rocks they were handling – leetso in the Diné language, or yellow dirt – were deadly.

> that "right to life" section of the Constitution

The US Constitution? Perhaps you are thinking of the Declaration of Independence?

Or the Fifth Amendment, formulating it in the negative: https://en.wikipedia.org/wiki/Fifth_Amendment_to_the_United_...

I believe it is important for us to consider where rights derive from. The Constitution and Bill of Rights are designed to protect rights that humans already have ("endowed by their Creator") and prevent the government from taking them away, or infringing on them. The law can grant ordinary civil rights, above and beyond intrinsic human rights, but if the Constitution isn't protecting the latter, then there is a problem.