Using harvested rainwater for drinking

Parameters used for using harvested rainwater for drinking

Dear India Water Portal,

We cultivate rain water from roof top with first rain flush theory. We also allow ample flush for secondary and third rain depending on quality of rain. We are using filtered rain water for daily drinking purpose.We have also installed a membrane based filter prior to drinking. We would like to understand what parameters should be followed while considering rain water for drinking ?

Thank you