Enter your FAS Used for Sample, FAS Used for Blank, Normality of FAS, and Volume of Sample into the Chemical Oxygen Demand (COD) Calculator to find your sample's COD value in mg/L, along with its Water Quality Status and Pollution Level.
Chemical Oxygen Demand (COD)
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Water Quality Status
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Pollution Level
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COD measures the capacity of water to consume oxygen during the decomposition of organic matter. It indicates the amount of oxygen required to chemically oxidize organic pollutants in water, making it a key parameter for assessing water quality.
COD is determined using the dichromate oxidation method followed by FAS titration. The formula is COD = (A - B) × N × 8000 / Sample Volume, where A is blank FAS volume, B is sample FAS volume, N is FAS normality, and 8000 is the conversion factor.
COD indicates the level of organic pollution in water. Higher COD values suggest greater organic contamination and potential environmental impact. It helps assess treatment efficiency and compliance with discharge standards.
COD is measured through a standardized laboratory procedure involving oxidation with potassium dichromate in acidic conditions, followed by back-titration with ferrous ammonium sulfate (FAS) to determine the amount of oxidizing agent consumed.
For drinking water, COD levels should typically be below 10 mg/L. Surface waters generally have COD values of 20-200 mg/L, while heavily polluted waters may exceed 200 mg/L. Lower values indicate better water quality.
BOD (Biochemical Oxygen Demand) measures oxygen consumed by biological processes over 5 days, while COD measures oxygen required for chemical oxidation. COD is faster to determine and typically higher than BOD, providing a broader measure of organic pollution.
COD determination is crucial for water treatment plant operations, environmental monitoring, and regulatory compliance. It helps assess treatment efficiency, monitor discharge quality, and evaluate the environmental impact of wastewater on receiving water bodies.