Am having the same problem of bitterness while drinking water only . first i felt it's some kind of water problem but after changing waters and even t?

Water taste: I suggest that you start with a basic metabolic panel on your blood work to exclude simple electrolyte issues or kidney problems. If that is all normal, see a neurologist.

Infection possible : A bitter taste in the mouth, dysgeusia, can come from multiple problems. The first we think about is infection in mouth, tonsil or in the nose or sinus disease, tooth decay The bad taste can also come from various medications that you take such as vitamins, heart medication, antibiotics and even certain foods such as Curcumin. Check the Internet for a list of meds. See physician if all neg.