From the site:
Dihydrogen Monoxide (DHMO) is perhaps the single most prevalent of all chemicals that can be dangerous to human life. Despite this truth, most people are not unduly concerned about the dangers of Dihydrogen Monoxide. Governments, civic leaders, corporations, military organizations, and citizens in every walk of life seem to either be ignorant of or shrug off the truth about Dihydrogen Monoxide as not being applicable to them. This concerns us.