Chemical Oxygen Demand (COD) Calculator

Chemical Oxygen Demand (COD) measures how much oxygen is needed to break down organic pollutants in water — a key indicator of water contamination levels. Enter your FAS Used for Sample, FAS Used for Blank, Normality of FAS, and Volume of Sample into the COD Calculator to get the Chemical Oxygen Demand in mg/L. Secondary outputs include Water Quality Status and Pollution Level based on your result.

mL

Volume of FAS (Ferrous Ammonium Sulfate) used to titrate the sample

mL

Volume of FAS used to titrate the blank solution

N

Normality of the FAS solution used in titration

mL

Volume of water sample used for analysis

Results

Chemical Oxygen Demand (COD)

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Water Quality Status

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Pollution Level

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Frequently Asked Questions

What is chemical oxygen demand (COD)?

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.

How can I determine chemical oxygen demand (COD)?

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.

What does chemical oxygen demand indicate?

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.

How is chemical oxygen demand measured?

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.

What is a good COD level for drinking water?

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.

What is the difference between BOD and COD?

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.

Why is determining COD significant?

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.