Photos: Tapping pure water in Argentina

Buenos Aires may mean "good air" in Spanish, but the water quality isn't always so laudable. Here, a horse in a poverty-stricken area of Hurlingham, Argentina, chews on trash and grass by a polluted stream. This stream is known for its contamination, and it's been the focus of several scientific inquiries. Rivers like this often contain pathogenic and odor-producing bacteria, heavy metals, nitrates and other toxins. Treatment in many water co-ops entails basic bleaching rather than filtration to kill bacteria.

Photo by Mariana Kasses