Santraginean mineral water is the main export of planet Santraginus V and, for those who cannot afford the seawater, a key ingredient in the Pan-Galactic Gargle Blaster. A strong body of opinion holds that this is not water at all, despite the claims on the label about how pure the spring is, and all that tosh about sparkling babbling brooks and so on. There is something highly suspect about the water on Santraginus V, as anyone who's ever met any of their fish will tell you. Even Santraginus V seawater is illegal on most planets. You can imagine what kind of beach communities they have. Obviously, drinking it is a bad idea.