"Journey to the Microcosmos: Microorganisms Are Cleaning the Water You Drink" explains how microbes make wastewater treatment possible. The video explores aquatic microorganisms in natural and engineered ecosystems, showing how bacteria, protozoa, fungi, rotifers, nematodes, and other microscopic life break down organic waste through self-purification. It introduces key science concepts and terms such as wastewater, pollutants, activated sludge, flocs, oxygen levels, microbial ecosystems, and reactor-based treatment. The program also connects environmental science, microbiology, ecology, and engineering by describing how treatment plants manage sewage and runoff using controlled microbial communities. Relevant to life science and environmental curricula, the video highlights the role of microorganisms in water quality, public health, and sustainable infrastructure. Part of the "Journey to the Microcosms" series.