Lack of magnesium can be associated with an abnormal immune function, as proven in acute and chronic infections. Moreover, the literature suggests that patients with bacterial infections, on average, have a statistically significant decrease in serum magnesium concentration. The aim of this prospective quasi-experimental study was to examine and determine whether the consumption of magnesium-rich bottled water improves the outcome in patients suffering from recurring urinary tract infections (UTIs). More specifically, the idea was to compare the outcomes of such patients (who consumed the aforementioned water) with the outcomes of equivalent patients who consumed regular tap drinking water. Forty-four adult patients aged between eighteen and eighty-four years that had a history of recurrent UTIs, participated. Participants were divided into two groups based on the type of water they consumed. The patients that consumed the local tap drinking water constituted the group A (N=22) and the patients that consumed the magnesium-rich bottled water constituted the group B (N=22). The required daily water intake was 2.0-2.5 litres. The tests that patients underwent when they initially entered the study (T0) were the following, a) urine analysis, b) urine culture, and c) measurement of serum magnesium levels. Furthermore, these tests were repeated during a scheduled follow-up, which occurred nine months after the participants entered the study (T1). After nine months of the different type of water consumption, there was no statistically significant difference concerning the number of UTIs between the groups (group A-group B). Moreover, patient who belonged to group B, had statistically significant higher serum magnesium levels than those in group A, regardless of their age. More studies are necessary to determine the effect of consuming magnesium-rich water on recurrent UTIs.