The dehydration, a physiological disturbance due to fluid depletion of the organism, is a common condition in the elderly and most common in the agonal state if not corrected with medical means. Alas, there is little evidence and a paucity of literature as well if one looks for firm data. Do we generally influence the course and duration of the dying process by hydrating or withholding fluids respectively and in what respect? We don't know. Where there is lack of evidence, ideology blossoms. To shed light on this issue an expert panel of members of palliative.ch convened in the Bigorio Monastery in 2009 with the intention to study existing data in order to formulate a concise guideline. Its title: "Hydration in the Palliative Care Setting: Consensus for Best Practice for Palliative Care in Switzerland". This document is available on the website of palliative.ch as a PDF file (go to Fachportal - Standards - best practice). Far beyond the realms of pure fluid physiology the process of decision making with regard to hydration therapy touches core issues of ethics and systemic communication as well. It poses substantial challenges to care teams as illustrated by a case presented in this article.