Ask any coffee lover if the type of water matters in their morning cup of coffee (or hourly) and just about everyone will say “yes”. There are three types of water available to home : affordable filtered water, tap (town) and expensive bottled water.
For this purpose (making coffee) bottled water is indeed a waste of money and resources, especially since numerous bottled waters are basically filtered (hopefully) town water that has been re-packaged and marketed. Nothing wrong with that but their are better alternatives.
Two camps “Tap Water Rules versus “Filtered Water Mob”.
If your spending good money on buying quality coffee beans from a much loved coffee roasting house than using a filtered water make perfect sense. Coffee purchased from specialty coffee suppliers can cost upto $100 a kilogram for Hawaiian Kona (see wikipedia).
Town water (tap water) has a taste of its own and depending on supplier it may have a fair amount of chlorine added which has a strong-ish taste to say the least. Coffee and more particularly the complex and subtitle flavors it often has are best served in filtered water to enjoy the taste of the coffee as it was meant to be.
Why bother filtering your coffee if you not going to filter your water. Using town water will require more maintenance as tap water contains calcium and that along with other salts etc start to block up parts of the typical espresso machine if you are using filtered water greatly reduces maintenance requirements.