Calculate water quality index (WQI) based on comprehensive water parameters with improved accuracy and confidence intervals.
The Water Quality Index (WQI) is a single number that expresses overall water quality at a certain location and time based on several water quality parameters. The objective of a WQI is to turn complex water quality data into information that is understandable and usable by the public.
Key Insight: A higher WQI value indicates better water quality. WQI values above 90 are considered excellent, while values below 50 indicate water that is severely polluted.
Excellent (90-100): Water quality is protected with a virtual absence of threat or impairment; conditions very close to natural levels.
Good (70-89): Water quality is generally protected but occasionally threatened or impaired; conditions rarely depart from natural levels.
Fair (50-69): Water quality is frequently threatened or impaired; conditions often depart from natural levels.
Poor (25-49): Water quality is almost always threatened or impaired; conditions usually depart from natural levels.
Very Poor (0-24): Water quality is always threatened or impaired; conditions always depart from natural levels.
| Parameter | Ideal Range | Significance | Common Sources |
|---|---|---|---|
| pH | 6.5-8.5 | Measures acidity/alkalinity; affects chemical reactions and aquatic life | Natural geological processes, industrial discharge |
| Dissolved Oxygen | >6 mg/L | Essential for aquatic life; indicates water's ability to support life | Atmospheric diffusion, photosynthesis |
| Turbidity | <5 NTU | Measures water clarity; affects light penetration and habitat | Soil erosion, algal blooms, wastewater |
| Total Coliform | 0 MPN/100mL | Indicator of fecal contamination and potential pathogens | Human/animal waste, sewage contamination |
| Nitrate | <10 mg/L | Excess causes eutrophication; health risk at high levels | Fertilizers, sewage, animal waste |
| Phosphate | <0.1 mg/L | Limiting nutrient for algal growth; causes eutrophication | Detergents, fertilizers, sewage |
| BOD | <3 mg/L | Measures organic pollution; high values indicate contamination | Organic waste, sewage, agricultural runoff |
| Heavy Metals | Varies by metal | Toxic to humans and aquatic life; bioaccumulate in food chain | Industrial discharge, mining, corrosion |
Disclaimer: This Water Quality Index Calculator provides results for informational and educational purposes only and does not constitute professional water quality assessment or advice. Actual water quality evaluation should be based on professional laboratory testing and analysis by qualified environmental engineers. Calculated results may vary depending on parameter weighting, measurement methods, and environmental conditions. We assume no liability for any direct or indirect damages arising from the use of this tool.