Hi Esther,
I assume the location is in Spain.
I agree with the previous post but slightly ++. From my experience (not EC) there can be at least 3 Depatments involved with the well's usage -
(1) A local official department (D1) is specifically assigned to initially authorise wells as potential drinking water/allied sources. They do basic micro-chemical -physical testing similar to previous post although somewhat expanded. If acceptable, responsibility for further testing is passed on to a Department (D2) associated with the intended use of any finished product.
(2) If food is involved, afaik Spain is a member of EC. The EC has issued a (highly) comprehensive BCP document covering sampling/analysis for potable water to be used in food-related situations (attached on this forum in various places). Unless Spain has it's own internal list (eg via Public Health Section) which is feasible, the EC list looks a logical choice. Department D2 either themselves or via a contracted Service Company analyse for compliance to the (likely) several pages of items listed. .
(3) I anticipate that various filtration/waste treatment systems will be involved. IMEX this can involve an additional Department (D3) who are particularly responsible for effluent control (eg BOD) but also become unavoidably concerned with the initial treatment materials/any associated chemicals.