A BOD bottle is a specialized lab container, usually borosilicate glass, used for the Biochemical Oxygen Demand (BOD) test, which measures water pollution by tracking how much oxygen microorganisms consume breaking down organic matter over five days at 20°C, featuring a unique flared mouth and stopper for an airtight seal to prevent air interference during incubation. These bottles, often 300 mL, are crucial for assessing water quality in wastewater treatment and environmental monitoring.