A downtown Budapest steakhouse, a hot afternoon in June, a table booked for a birthday. One guest arrives early, sits down, and asks for a glass of tap water. The waiter says, politely, that the house only serves bottled mineral water. The guest doesn't drink bottled water and declines. When the rest of the party arrives, they talk it over for a minute and, birthday or not, leave to eat somewhere else.
The margin on a bottle of mineral water is real, but so is the bill for a table of six that walks out before ordering. How many bottles do you have to sell to cover one reservation that turns around at the threshold?
The water costs almost nothing, serving it does.
The liquid itself is effectively free.
But the glass doesn't pour, carry and wash itself.
An illustrative breakdown from the Austrian Economic Chamber's Burgenland branch put the water inside a €1.80 bottle of mineral water at about €0.38, and the tap-water equivalent at €0.001, while staff (€0.52) and overheads (€0.52) were identical in both columns. The figure is old and not a benchmark, but the structure is correct: you aren't selling water, you're selling the labour, glassware, washing, ice and breakage around it. Refusing tap water doesn't protect a product margin, it’s the service you've decided not to give away.
