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The Water Quality Index (WQI) converts multiple water quality parameters into a single number that communicates overall water health. Developed by the National Sanitation Foundation (NSF), the WQI ranges from 0 (worst) to 100 (best) and is widely used for river, lake, and drinking water monitoring.
This calculator evaluates five key parameters: dissolved oxygen, biochemical oxygen demand, pH, turbidity, and nitrate. Each parameter is converted to a sub-index score and weighted based on its relative importance to overall water health.
Each parameter is scored 0–100 via sub-index curves, then weighted: DO (0.17), BOD (0.11), pH (0.11), Turbidity (0.08), Nitrate (0.10). The WQI = Σ(sub-index × weight) / total weight × 100. Scores: 90–100: Excellent, 70–89: Good, 50–69: Medium, 25–49: Bad, 0–24: Very Bad.
A WQI above 70 is suitable for most uses. 50–70 requires treatment for drinking. Below 50 indicates pollution requiring remediation. Low dissolved oxygen is the most common indicator of water quality degradation.
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Healthy river conditions.
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Degraded water body.
Water Quality Index is a quantitative measure used in environmental science and ecology. It represents key metrics that help researchers, policymakers, and individuals understand environmental impacts. The specific definition and measurement methodology are established by international scientific organizations and regulatory bodies.
What parameters affect water quality involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
Water Quality Index is a quantitative measure used in environmental science and ecology. It represents key metrics that help researchers, policymakers, and individuals understand environmental impacts. The specific definition and measurement methodology are established by international scientific organizations and regulatory bodies.
How is dissolved oxygen measured involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
Why is BOD important involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
What causes turbidity in water involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
How do nitrates enter water involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
What pH range is safe for aquatic life involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
Who developed the WQI involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
How often should water quality be tested involves analyzing relevant parameters using established scientific methodologies. Our calculator applies peer-reviewed formulas and standard emission factors to provide accurate results. The specific approach varies by parameter but follows guidelines from organizations such as the EPA, IPCC, and relevant scientific bodies.
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