Water Quality Index Calculator

The Water Quality Index Calculator scores a water sample on a 0–100 scale by combining chemical, physical, and biological measurements into a single rating. Enter your pH level, dissolved oxygen, turbidity, temperature, total dissolved solids, biochemical oxygen demand, and electrical conductivity, then select your water source type. You'll get a Water Quality Index score, an overall water quality rating, and individual sub-scores for pH, dissolved oxygen, and turbidity.

pH scale from 0 (acidic) to 14 (basic)

mg/L

Amount of oxygen dissolved in water

NTU

Measure of water clarity

°C

Water temperature in Celsius

mg/L

Total amount of dissolved substances

mg/L

Amount of oxygen needed by bacteria

μS/cm

Ability of water to conduct electricity

Results

Water Quality Index

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Water Quality Rating

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pH Index

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Dissolved Oxygen Index

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Turbidity Index

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Frequently Asked Questions

What is a Water Quality Index (WQI)?

A Water Quality Index is a numerical scale that combines multiple water quality parameters into a single score to indicate overall water quality. It simplifies complex water quality data into an easy-to-understand rating system.

What WQI score indicates good water quality?

Generally, WQI scores of 90-100 indicate excellent water quality, 70-89 is good, 50-69 is fair, 25-49 is poor, and below 25 indicates very poor water quality unsuitable for most uses.

Which parameters are most important for water quality assessment?

Key parameters include pH (acidity/alkalinity), dissolved oxygen (essential for aquatic life), turbidity (clarity), temperature, total dissolved solids, and biochemical oxygen demand. Each parameter affects water quality differently.

How does pH affect water quality?

pH measures water acidity or alkalinity. Optimal pH for most aquatic life is 6.5-8.5. Values outside this range can harm aquatic organisms and affect the solubility of nutrients and pollutants.

Why is dissolved oxygen important in water quality assessment?

Dissolved oxygen is crucial for aquatic life survival. Low oxygen levels indicate pollution or eutrophication, while adequate levels (typically above 5 mg/L) support healthy aquatic ecosystems.

What causes high turbidity in water?

High turbidity results from suspended particles like soil, algae, or organic matter. It reduces light penetration, affects photosynthesis, and can harbor harmful microorganisms, indicating poor water quality.

Can this calculator be used for drinking water assessment?

This calculator provides a general water quality assessment primarily for surface water. For drinking water safety, additional parameters like bacteria, heavy metals, and specific contaminants should be tested by certified laboratories.

How often should water quality be monitored?

Monitoring frequency depends on water use and source type. Surface water should be tested monthly during peak usage, while groundwater can be tested quarterly. More frequent testing is needed if pollution sources are nearby.