Rejuvenation of Dormant Groundwater Wells

I have recently reactivated a borehole which was used for drinking water 20+ years ago, to be utilized for household purposes and drinking water.

I would like to know what the recommended procedures are (besides thorough flushing of the well prior to use), to ensure the water is safe to drink.

I will be sampling the water to be analysed for chemical parameters, and am considering analyzing it for biological parameters as well. However, the well is located in a very remote area, and analysis of biological parameters is costly, which is why I am considering only analyzing its chemical parameters.

Any advice would be welcome.