I never gave it a lot of attention but you make a very good point. I too have noticed the varying water taste issues in many restaurants in the area. It seems like a simple inline taste and odor filter would do wonders to improve the taste of the water. I wonder, though, if installation of such a unit will raise other issues with any regulatory or governing bodies.
As an example, I agree with many others on this forum thaqt the food at the Chinese restaurant in Belmont, on Rte 3, across from Baron's (obviously I can't remember the name) is some of the best around, but the taste of the water is terrible. HMMMM...I wonder if restaurants add the awful taste to the water to encourage you to order some expensive exotic drinks?