For my project I am developing an automated water dispensing unit using Arduino. However there is one requirement is to measure the purity / quality of water being dispensed.
Please let me know if there is any quality sensors that can detect the purity / quality of water? I am sorry I am not knowledgeable on same
Potable water requires that many conditions are checked. You would need to check for chemical contamination from many different chemicals. You would then need to check biological contamination.
With all these checks, I would not rate your chances of monitoring for good drinking water via an Arduino as good.
I am not aware of sensors readily available for all harmful bacteria and viruses.
You would need to make sure that the source of the water is good rather than checking with sensors.
I agree to that but is there any Electrical conductivity sensor I can make use to monitor the amount of nutrients, salts or impurities in the water.
What would be the nearest sensor for the same functionality - the water dispensed is via a filter that takes care of removing impurities harmful bacteria and viruses.
A reverse osmosis filter will take all impurities, right down to virus' and dissolved salts.
Anything else is really, really hard and/or really, really expensive.
Virus and bacterial "detection" is specific, you can get a 12V reverse osmosis filter for WAY less money
As cyberteque says, but assuming you have good filtering and only want to detect if dirty water is to be detected, simple electrical and light conductivity would be a start.
These checks will NOT ensure the water is safe.
Probes in the water and using ADC to read the voltage could check for for salts.
A light shining through the water on to a photo sensor can detect turbid water.