Deciding whether water chemistry is worth paying attention to before buying more gear

I've been tempted to buy a better grinder, but a friend suggested trying different brew water first. Our tap water leaves scale in the kettle, and coffee often tastes dull even when I think the grind and recipe are close. I'm not planning to turn the kitchen into a chemistry lab. Would a side-by-side tasting with bottled low-mineral water tell me anything useful, or is water chemistry a rabbit hole best left until the basics are truly consistent?