When our oldest daughter got married, we had the rehearsal dinner at our house... nice summer gathering. My son-in-law to be had been drinking bottled water from the fridge and wanted a couple for him and his parents to take when they left. No problem.
What they did not know was that I had done a little experiment, he did not like our tap water (from well, 52 degrees) since it was "too hard". He brought some bottled water with him when dating our daughter. I saved the bottles from buying some water and refilled them with tap water and kept in fridge. He had no trouble with them.
That was over 4 years ago, he drinks water from the tap now.