It’s not up to coffee shop owners to be sure grown adults take enough water on board to offset the onset of dehydration, surely this is the individuals responibility. The wate is a pallet cleansing routine and in my experience over 40 years the main type of water I have seen served was primarily ordinary still water from the faucet or tap, typically sparkling water costs money even if the shop employs a type of soda stream device that adds the gas to ordinary water, either way mostly(maybe outside Italy)it’s plain still water I see being served on a regular basis.
PS* In relation to @MTSan’s question regarding the relationship between roasting coffee and mineral water, there is none, other than the fact that some ppl use bottled water to make their coffee, they claim the mineral water in say Evian bottled water produces a better cup of coffee although I doubt coffee shops use bottled water, too expensive, but they do use filters in their water source. Regarding the roasting and the making of the coffee. Coffee is at its best(freshest) when you grind the coffee beans just before you make the coffee, weather it’s an espresso machine or a pour over or aeropress, chemex ect. The four hours I don’t know about but I do know the freshest of coffee is made when you use fresh coffee(roasted in the last 2 weeks). If you are using tap water which is fine it is best tou fill you machine the previous night, this gives the water time for the added chemicals put in the water by local Govt(fluoride etc) to evaporate. The coffee in supermarkets, esp ground coffee where you see the best before date on the bag as 2 years away, this is not fresh coffee even if it is vacume packed. Buy your coffee from a shop that shows when the beans where roasted, of course this is assuming you are making your coffee at home, a good coffee shop will know all this, look for speciality coffee shops, at least these shops know what they are doing and their mission is to produce the best tasting coffee they can.
