The sense of taste can be altered by many different conditions, including zinc deficiency, states WebMD. However, the idea of water having a flavor apart from any additives or minerals it may contain is controversial, as described by Popular Science.
Some conditions that alter the sense of taste include hepatitis, oral cancer, and Alzheimer's, states WebMD. Certain medications can also alter taste perception, including several drugs designed to treat thyroid problems. However, these conditions cannot directly alter the taste of water, as pure water itself does not have any taste to alter.
Water has traditionally been thought of as lacking any flavor whatsoever in its pure state, states Popular Science. Scientists have known for some time that drinking water after tasting something else, even one's own saliva, can alter the perceived taste of water, though. For example, eating something salty can make pure water seem bitter.
Furthermore, zinc deficiency can completely mask the taste of zinc in a glass of water, states the website Clinicians. In fact, asking a patient to report the perceived taste of a glass of water is a common test for zinc deficiency.
The idea that it is possible to taste water on its own is controversial. There is some evidence that suggests humans can taste pure water, but the scientific community has been very critical of the research indicating this. As of 2015, most scientists believe that water only has flavor as an aftereffect of whatever was being tasted before it. Insofar as a condition can be described as altering the taste of water, it can only be said to do so as a consequence of this after effect.