You probably will not find a website, you need to get copies of the well logs when wells were drilled. The other option is some wells will check their static levels, which means what depth is the water table when there is no pumping. I used to be the assistant manager of a well system here in California, and our State keeps copies of the well logs, so the agency who keeps those records probably varies from country to country. Occasionally, someone will get a government grant to do a report for a whole watershed, especially one heavily used for agriculture or a large city as a water supply, but they have to put the data together one by one.

In global scale - see

GRACE: Gravity Recovery and Climate Experiment: Surface mass, total water storage, and derived variables | Climate Data Guide (ucar.edu) https://climatedataguide.ucar.edu/climate-data/grace-gravity-recovery-and-climate-experiment-surface-mass-total-water-storage-and

and https://grace.jpl.nasa.gov/

Thank u