Microbiological and chemical characteristics of potable bottled water in Tanzania

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Sokoine University of Agriculture


Tanzania has experienced an increase in the consumption of bottled water as a result of the population building trust that it is safer than tap water. It is the interest of public to consume water of high quality both microbiologically and chemically. Due to the fact that bottled water is produced from different geographical regions, it is expected to have different qualities in microbial flora loading, essential elements and heavy metals. The aim of this study was to assess the quality and safety of the bottled water produced from different geographically areas of Tanzania and make recommendations to the public and surveillance authorities. A cross-sectional study in which a total of 15 brands of bottled drinking water manufactured in 10 Regions which constitute four geographical zones of Tanzania were analyzed for microbiological contamination using the membrane filtration method and reported in terms of MPN/100 mls. Also Total Plate Count was done and reported in cfu/ml. Analysis of the presence of Cryptosporidium oocysts used the concentration method which consisted of three stages:- concentration, separation and microscopic detection. The Inductively Coupled Plasma – Optical Emission Spectroscopy (ICP-OES) was used to determine the concentration of both essential macro elements (Calcium, Magnesium, Potassium and Sodium) and heavy metal (Lead, Mercury, Cadmium and Arsenic) and the results were expressed in milligram per litre. Total coliform was detected in 2 brands of bottled drinking water from Lake Zone and Eastern Zone, also 10 brands of bottled drinking water from Northern Zone 3 out of 3, Lake zone 3 out of 5, Eastern Zone 2 out of 5 and Southern Highland Zone 2 out of 2 had a total bacterial count loads of above 500 cfu/ml, Eastern zone and Lake Zone each had a bottled drinking water brand exceeding 3 x 105. Cryptosporidium oocysts were not detected in all 15 bottled drinking water brands so complying with the standards. The concentrations of all three elements Calcium, Magnesium and Sodium were very low and statistically significant at a ‘p’ value of 0.05 as compared to their recommended maximum values by TBS which are 250mg/L, 100mg/L and 200mg/L for Calcium, Magnesium and Sodium respectively. Potassium was not compared because up to this moment there is no recommended value provided by TBS/WHO. Another objective was to compare the information displayed on the label if they match with the actual concentration in bottled drinking water. With exception of Magnesium which was statistically different at a ‘p’ value of 0.05, the remaining had no difference with their label. For heavy metals the results show that, the concentrations obtained in all samples were within the legal limits. Microbiologically, all bottled drinking water brands were safe to drink and can be used to process other food. The consumers of bottled water should make sure they do not depend on water to get their essential elements, because it was observed to have very low concentration of macro elements. Other sources of food higher in these elements should be used. The manufacturers of water should make sure that they balance the lost minerals before water is packed for sale.


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Microbiological, Chemical characteristics, Potable bottled water, Bottled water, Water, Tanzania