Bad drinking water IS the end of the world. Nonchalant cliches like this make the right to drink clean and clear water seem like something that is mostly fairly applied throughout the world.
He's not suggesting people buy potassium permangranate to purify their water. He's saying that the substance that is making the water pink is what people use all the time to purify water. That makes the assertion by the local government that the water is safe much more believable.