In just four lines, the speaker admits to a small contradiction: they have water, but they are still hungry. The tone then shifts with the question "But what do I care?" It sounds casual, almost shrugging, as if the hunger is something they have decided not to dwell on.
The last line, "The water is tasty," is where the poem turns. Water has no real flavor, so calling it tasty suggests the speaker is making the most of very little. It could be genuine contentment, or it could be a way of convincing themselves they are fine. The poem leaves that open.
The mood is quiet and a little ambiguous. There is a hint of lack, since hunger is named right away, but there is also stubborn calm and even a flicker of defiance. Because the poem is so short and plain, the reader is left to decide whether this is acceptance, denial, or simply a person finding pleasure where they can.