INVESTIGATION THE SOURCE OF BOTTLED DRINKING WATER USING STABLE ISOTOPES: CONNECTION BETWEEN HYDROGEOLOGY AND URBAN WATER MANAGEMENT

Stable isotopes of oxygen and hydrogen in water have been used extensively to understand the hydrologic cycle in many places worldwide, and the findings provide a recognizable signature relating to various processes in the water cycle. The oxygen and hydrogen isotopes are not only a powerful tool to study the hydrologic cycle but also can have implications in our daily life, for example the human diet. Bottled waters are now are an increasingly significant component in our daily life and a relevant segment of the food market, especially in tourism industry. Fraudulent operations are always possible in terms of product misrepresentation. For example, doubts will always remain as to whether a bottle of water is actually from spring fed by a deep artesian aquifer or from local municipal water supply.

In this study we explore the possibility of using stable oxygen and hydrogen isotopes to verify the claims made by select vendors of bottled water in Egypt. In other words, we investigate, based on isotope ratios if the claims of source of the water such as “water from deep well”, “water from mountain springs” etc. can be sustained. This may therefore qualify to be a study in “water adulteration”. This is an important issue not only in tourist hot beds such as Egypt but in many parts of the world where use of bottled water is becoming increasingly popular.

Seventeen samples of different bottled water brands were obtained from the Egyptian market . Water samples were stored in small vials until the time of analysis. Available record of source locations suggest that our sample set includes bottled water with sources from three countries other than Egypt. Brand names have been withheld because of the sensitive nature of the study. Oxygen and hydrogen isotope ratios were determined using the new generation Infra red Laser Absorption Spectroscopy. Variability in δ²H and δ¹⁸O values among the measured bottled waters range from –80.18 to +23.85 ‰ and from –11.51 to +2.55 ‰, respectively. Isotope ratios confirm the claimed origin of some of the samples (7 samples). At the same time there are samples (10 samples) whose sources appear questionable.

Our findings suggest that stable isotopic fingerprint can be used for the authentication of bottled waters and for certification of the claimed sources of bottled water.