You can use the formula of geometric mean. I had use this model and get valuable results.

Many WQI formulas exist. WQI gives you a comprehensive overview of the potability of water on an area. It is a function of Geology of the area and human activities see domiciled in the area. Use the WQI that encoporates qi and Ci in their calculation. They are more reliable and effective.

Dear Ajmal,

Water Quality Index (WQI) is the best tool which provides a suitable mean of briefing complex water quality data that can be simply understood by the community and it is a great tool for managers and decision makers. There are lot of WQI are already developed for different purposes,

• US National Sanitation Foundation Water Quality Index (NFSWQI)
• British Colombia Water Quality Index (BCWQI)
• Oregon Water Quality Index (OWQI)
• Canadian Council of Ministers of the Environment (CCME)

According to my knowledge CCME WQI is very use full and easy to determine the WQI values for different purposes such as,

• Drinking
• Livestock
• Aquatic environment
• Irrigation

In this CCME WQI, you can use your own water quality standard values or ranges according to your region or the country. Since most of present WQIs, developed its own model which only representing exact area or region.

Hope following articles will help you for further calculations,

Article Water Quality Index (CCME-WQI) Based Assessment Study of Wat...

Article ASSESSMENT OF WATER QUALITY INDEX FOR GROUNDWATER IN THE KEL...

Thank You for your valuable suggestions. These have been of great help Yohan Mahagamage Akobundu Nwanosike Amadi Abdulmuhsin S. Shihab

You can use the method of geometric mean. First you must found the weight of each factor according to the type of water use (drinking, industrial... ). Then you can found the geometric mean of these weights and multiply the result with 100 and the result represent the water quality Index.

Dear Ajmal

I think the Canadian Council of Ministers of the Environment (CCME) WQI is very useful and easy to calculate the WQI values for Drinking and Aquatic environment

Thank You for your valuable suggestions. These have been of great help Hussein Jabbar Abdulmuhsin S. Shihab