Restaurant and cafe owners should take heed of the power of social media, especially when they concern complaints and criticisms about their own businesses.
There is a great article at Hospitality Directory that is worth reading which also contains some common sense lessons in handling any complaints.
Also, the restaurant owner in Tasmania might like to consider that if his is a licensed premise, one of the conditions of his license could be "all licensed venues where alcohol is consumed on the premises are required to provide free water to patrons if requested" rather than just selling bottled water.
This is certainly the case in Queensland, New South Wales and Victoria.