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[Mineral water or tap water? A systematic analysis of the literature concerning the question of microbial safety].

BACKGROUND
Based on sporadic reports of microbial contamination of mineral waters, it has been recommended that, for safety reasons, particularly immunocompromised patients should drink tap water rather than bottled mineral water. However, in terms of safety, evidence of the clinical consequences may allow a better estimate than a positive in vitro test for contamination. Therefore, we reviewed the literature on documented disease outbreaks due to contaminated mineral and tap waters.


MATERIAL AND METHODS
We performed a systematic search of the literature using the database MEDLINE. In order to identify evidence relevant for Germany, we restricted our search to the years 1985-1997 (i.e. legal force of the mineral and table waters act in Germany) and the countries of Central and Northwestern Europe as well as the USA and Canada.


RESULTS
Cases of contamination of tap water were documented in nearly all countries included. In 35 communications we found reports on a total of 423,000 cases of disease outbreaks due to contaminated tap water, in some cases even with lethal outcome. Main diagnosis was gastroenteritis, and main species of microorganism was crytosporidium. In contrast, there was no documented case of disease outbreak due to contaminated bottled mineral water.


CONCLUSION
Tap water as well as bottled water are both supremely safe components of nutrition. The recommendation that tap water is better than mineral water, particularly for high-risk patients, is not supported by the literature.