Dear Adil,

Here is an interesting paper that deals with the assessing of water quality index (WQI) for the ground water of Indore City and its industrial area.

http://www.isca.in/IJES/Archive/v3/i5/3.ISCA-RJEngS-2014-24.pdf

With my best regards

Prof. Bachir ACHOUR

thank you, sir , but still, the idea about relative weight being equal to 1 or not is still unclear.

See

Schodhganga

Thesis of my student Sonika Sharma 

Water Qualitu Index of Jaipur and agglomerates

I suppose that will help you

Thank you, Prof. Chhipa

Dear Adil Masood,

I am explaining the WQI in a simple way for your easy understanding.

WQI: It may be defined as a rating reflecting the composite influence of different water quality parameters on the overall quality of water. The main objective of computing of water quality index is to turn the complex water quality data into information which is easily understandable and usable.

Selection of  parameters: First study the Indian Standard (BIS 2004) for drinking water specification. Here,  the physicochemical parameters along with the desirable limits and related health effects are given. A parameter has to be selected based on its impact in the overall quality of water and heath effects. This standard is freely available in net. However, I am enclosing the same for your convenience (see below).

Computation of WQI: The WQI is computed following the three steps.

First step – Assigning of weight (wi) to the selected water parameters (e.g., pH, TDS, TH, HCO3, Cl, SO4, NO3, ……) according to their relative importance in the overall quality of water for drinking purposes (weight may be from 1 to 5).

Second step – Computation of a relative weight (Wi) of the chemical parameter using the following equation:                                                                                

Wi = wi / ∑  wi ( i = 1 to n) 

where, Wi is the relative weight, wi is the weight of each parameter and 'n' is the number of parameters

Third step - Assigning of a quality rating scale (qi) for each parameter, as below:

qi = (Ci / Si ) x 100                                                                                       

where,  qi is the quality rating, Ci is the concentration of each chemical parameter in each water sample in mg/l, and Si is the guide line value/desirable limit as given in Indian drinking water standard (BIS 2004).

For computing the WQI, the sub index (SI) is first determined for each chemical parameter, as given below:                                                                            

SIi = Wi x qi     

WQI = ∑ SIi - n                                            

where, SIi is the subindex of ith parameter; Wi is relative weight of ith parameter; qi is the rating based on concentration of ith parameter and 'n' is the number of chemical parameters.

The water may be classified into five types based on computed WQI as given below:

WQI range and water type:

< 50             

Excellent water;

50 - 100           

Good water;

100- 200          

Poor water;

200 – 300         

Very poor water;

> 300                

Water unsuitable for drinking.

For more details, you can consult my paper published in 'Water Environment Research (USA)'. The link is given below:

https://www.researchgate.net/publication/280062602_Hydrogeochemistry_and_Water_Quality_Index_in_the_Assessment_of_Groundwater_Quality_for_Drinking_Uses

Give your feedback. With good wishes - Dr. Asit

Article Hydrogeochemistry and Water Quality Index in the Assessment ...

Asit sir,

i got Ur clarification and it helped me  a lot thank you.

I need to put across certain points :

1) I've calculated  WQI using weighed Arithmetic index method (Brown et al,1972) where proportionality constant 'k' is also computed. Also i haven't considered Wi as in your case.

2) I have also incorporated the effects of COD  and BOD and other physio-chemical factors in my computation of Groundwater WQI. But there is no permissible limit for these parameters in BIS ,but limits are stated in WHO so i have taken WHO/BIS/ICMR standards in computation of Sn(see the paper attached)

I have attached a file which correlates my work .

am i in the right direction or i need to make certain alterations..??