National Sanitation Foundation

Parameters: Temperature, pH, Dissolved Oxygen, Turbidity, Fecal Coliform, Biochemical Oxygen, Total Phosphates, Nitrates, Total Suspended Solids

Links:

• Calculator: Here you can input data about any number of parameters and have a WQI result level. The page have charts relating the water quality value derived with the level of each parameter.
• National Sanitation Foundation Water Quality: Explains the index.

UNEP

Parameters: Dissolved Oxygen, pH, Conductivity, Nitrogen, Phosphorus

Links:

• Water Quality Index and Indicators: explains the calculation ('Global Drinking Water Quality Index' section)
• Water Quality: Development of an index to assess country performance