That depends on your definition of "we". As a society, we can regulate companies and punish the offenders (e.g. don't dump toxic waste into sources of drinking water or you'll get prosecuted). As individuals, there's not much we can do directly. How to translate individual actions into societal action is kind of the fundamental question of civilization, and if there's a uniform solution for how to achieve it, I don't think we've managed to come up with it yet.