Ancient Mayan water filters stopped a lot--just not mercury poisoning

The civilization made the most of its technology, but everything has its limits. Mayan society often relied on cinnabar, a deep red pigment that got its hue from mercury sulfide. Breakthroughs, discoveries, and DIY tips sent six days a week. A trio of ancient reservoirs in present-day Guatemala is revealing both the strength--and limitations--of Mayan water science. While the civilization's purification techniques resulted in comparatively clean drinking sources, archaeologists say the unknowable consequences of a commonly used, deep-red pigment consistently subjected the Indigenous population to toxic mercury poisoning .