Research Journal of Chemical Sciences ______________________________________________ ISSN 2231-606X   Vol. 2(7), 21-26, July (2012) Res.J.Chem.Sci. International Science Congress Association        
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Chemical Water Quality of Bottled Drinking Water Brands Marketed  in Mwanza City, TanzaniaMihayo I.Z. and Mkoma S.L.* Dept. of Physical Sci, Faculty of Science, Sokoine University of Agriculture, Chuo Kikuu, Morogoro, TANZANIAAvailable online at: 
www.isca.in
Received 24th March 2012, revised 28th March 2012, accepted 29th March 2012Abstract Water is a useful resource for domestic, industrial and agricultural purposes and its importance to man cannot be overemphasized due to its essentiality in body metabolism and proper functioning of cells. The present study was carried out to determine the physico-chemical quality of bottled drinking water brands available in retail shops in Mwanza city (Tanzania), and compare with drinking water standards. The results show that water type for different bottled water brands when classified according to TDS ranged from very low concentrations (brands A and B) to low concentrations (brands C, D, E, and F). Based on the classification criteria of total hardness, most brands were considered to have soft water except for brand E which had moderately hard water. The dominant component to all bottled water brands was SO2 accounted 48% to 90% of the total major ions, whereas Cl accounted for 8% to 25%. Somewhat high contributions up to 20% was observed for Ca2+, while Mg2+ was below 9%, and Fe2+ and NO were below 6%. Brand D has exceptionally high levels for Cl, NO, and Mg2+ ions. When compared with Tanzania Bureau of Standards (TBS) and World Health Organization (WHO) guidelines for drinking water, analysed parameters in all brands were within TBS and WHO limit values for drinking water. The study therefore concludes that the analysed bottled water brands are safe for human consumption. However, it recommends other water quality parameters such as microbiological and heavy metal be studied in future. Keywords: Packaged drinking water, quality parameters, TBS and WHO standards, Tanzania. IntroductionWater is a useful resource for domestic, industrial and agricultural purposes and its importance to man cannot be overemphasized due to its essentiality in body metabolism and proper functioning of cells. Though, water is abundant in nature occupying 71% of the earth surface, only 1% is accessible for human consumption. Access to adequate supply of safe drinking water for all is one of the primary goals of the World Health Organization. In Tanzania, only 54% of the population has access to improved water supplies and 24% have access to adequate sanitation. Bottled water is one of the reliable healthy drinking water in any parts of the world including Tanzania having undergone through series of treatments. Therefore, bottled water is widely accepted as potable and thereby free from physical, chemical and microbiological contaminants that could cause adverse health effects in humans when consumed.  In Africa, scarcity and water pollution constitute a major challenge for sustainable water resources management. Despite the World Health Organization’s guidelines for drinking water quality, water pollution in various sources has been increasing over recent decades in most countries7-9. On local scale in Tanzania, people depended on tap water, surface water, and groundwater which unfortunately are polluted10-12. In addition, bottled water was widely accepted as potable and healthy drinking water; thereby free from contaminants that could cause adverse human health effects. In recent year, different brands of bottled water have been produced using series of treatments and packaging. Though in Tanzania is mandatory to register brands of bottled water for quality production13-14, there are influxes of replica brands into the markets which has been posing threat to people’s health15-16. Bottled water remains the highest consumable commodity especially for the middle and high income social classes in urban areas, and since is processed from various sources, is important to examine it quality. Therefore the aim of this paper is to assess the physico-chemical quality parameters of brands of bottled water consumed in Mwanza city, Tanzania. A comparison among brands and with the prescribed Tanzania and World Health Organization drinking water standards was also assessed.  Material and MethodsStudy area: The present study was conducted in Mwanza city (Latitude 2° 31' 0.01"S and Longitude 32° 53' 60"E) that is located on the shores of Lake Victoria in Northern Tanzania. The population of the city is current estimated to be 0.8 million people and 86% of its residents including industries and agricultural activities depend on Lake Victoria as the major source of water17. However, other water sources including groundwater (boreholes and wells) and bottled water of various brands are available for drinking and other domestic purposes.  
Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X  Vol. 2(7), 21-26, July (2012)   Res.J.Chem.SciInternational Science Congress Association 
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Sampling and analysis: This study was limited to assessing six bottled mineral water brands available in retail shops in Mwanza city that were purchased once a week for one month from the public markets. To keep the brand names anonymous, bottled water samples were given alphabetical code from A to F and this convention used throughout the text. Out of
 
the 6 brands, 5 brands (excluding A) had most important parameters (pH, Na, K, Mg2+, Ca2+, Cl, SO2, and NO) on their bottle labels. Brands D had in addition to the named parameters, TDS and HCO, brand E had TDS, and F had Fe levels of the water labelled on their bottles. One brand (A) reported generalized information on pH, Na, Mg2+, Cl and NOparameters on its label. Three brands A, C, and E are tapped from Lake Victoria, snow of Mt. Kilimanjaro and boreholes respectively while the sources for other brands B, D and F were not indicated on the labels.  From each brand, two samples were analyzed for the physico-chemical parameters immediately after sample collection. The parameters include pH, electrical conductivity (EC), total dissolved solids TDS, turbidity, hardness and alkalinity, chloride (Cl), sulphate (SO2), nitrate (NO), Magnesium Mg2+, Calcium Ca2+, iron (Fe2+). The pH was measured using a pH meter, EC by conductivity meter, turbidity by turbidity meter, and TDS was calculated by the relationship: TDS = 0.45 × EC. Alkalinity, hardness, calcium, magnesium, and chloride were determined by titration method where by the volume of sample with indicator was titrated against the volume of reagent of known concentration (morality). Sulphate was determined by turbidimetric method, nitrate by colorimetric method, and iron by phenanthroline spectrophotometry method. It should be noted that other important parameters like Na, K and microbiological due to laboratory technical problem during study period. Results and DiscussionClassification of bottled Water brands: Different hydro-chemical classification systems can be used to classify water types. In the present study, the European Union (EU) mineral water directive18 was used to classify the water according to TDS and total hardness. The classification systems used to identify the chemical similarities and/or differences between bottled water brands. The criteria for the chemical composition of mineral water according to the EU mineral water directives are given table 1. The criteria show a distinction based TDS and a further specification based on some characterizing cations and anions.  Table 2 shows classification of brands of bottled water in accordance with EU mineral water directive (TDS). For the case of brands A and B fall in the class “very low mineral concentration” (with TDS50 mg/l), brands C, D, E and F fall in class “low mineral concentration” (with TDS between 50-500 mg/l). The classified brands of bottled water for this study based on total hardness are also shown in table 2. Five of the brands A, B, C, D and F with hardness between 0-50 mg/l are considered soft water; brand E with hardness between 50-100 mg/l is considered moderately hard water. Total hardness in water is caused by dissolved calcium and to a lesser extent magnesium and total hardness. EC, TDS and Turbidity: The chemical content of bottled water is determined by the composition of the source it is abstracted from. For example, similar types of rock may lead to different types of mineral water. The chemical content depends on the availability of mineralizing agents, such as COconcentration, redox conditions and the type of adsorption complexes19. Levels of EC, TDS and turbidity in bottled water brands and their comparison to TBS and WHO limit values are presented in table 3. The ranges for these parameters were: 17.4–280 S/cm for EC with a median of 185.5 S/cm; 7.8-126 mg/l for TDS with a median of 83.5 mg/l; and 0.0-1.0 NTU for turbidity with median of 0.5 NTU. There is a variation between EC and TDS values of the bottled water brands; this depends on the origin of the water and the treatment or purification method applied during bottling process. Electrical conductivity in water is usually used as a measure of ionic concentrations. The low EC of brand A is due to its low ionic concentration and higher in brand D is due to high ionic concentrations, and this also can be applied in TDS because they are related. Turbidity in all brands is very low because bottled water brands are highly flirted during processing.  Concentration of Major constituents: Table 4 shows the analytical results of major constituents found in bottled water brands together with the corresponding standards values used in this study. The pH of all brands was around neutral ranging from 7.3 to 7.6 with a median of 7.4; this may have been done in processing as recommended for drinking water. The concentration ranges for the major constituents (in mg/l) are: 16-79 for alkalinity with a median of 42; 20-66.5 for total hardness with a median of 37; 3.4-14 for Ca2+ with a median of 9; 0.1-8.9 for Mg2+ with a median of 2.9; 0.18-0.2 for Fe2+ with a median of 0.2; 2.5-48.2 for Cl with a median of 10; 5.9-87.7 for SO2  with a median of 23.9; and 0.1-3.5 for NO with a median of 0.3. Brand E has higher concentration of Ca2+ and Cl, brand C has the higher value of Mg2+ (after brand E) as from its source of snow the higher value can be because of presence of magnesium-rich minerals such as olivine and pyroxene in the volcano environment. Of all brands Ca2+concentration was higher than of Mg2+ this means that hardness of water come mostly from Ca2+ concentration. Fe2+concentration in all brands was low, this can be due to methods of processing that ensure the smaller concentration of Fe2+. Generally, the results show that the bottled water brands are quite different in characteristics. The observed variations in the chemical constituents might be resulting from the origins, residence time, atmospheric conditions and purification or treatment process employed by the manufacturers. In fact all the constituents in all brands are within the recommended TBS and WHO standard limits for drinking water. 
Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X  Vol. 2(7), 21-26, July (2012)   Res.J.Chem.SciInternational Science Congress Association 
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Contribution of major ions: The average concentrations in bottled water brands of proportions of major ions are shown in figure 1. It is clearly that SO2 was the major component to all bottled water brands and the lowest SO2 level was observed in brand B. Brand D has exceptionally high levels for most ions such Cl, NO, and Mg2+. The percentage attributions of the analysed major ions concentrations to each of the six bottled water brands are given in figure 2. The dominant component, SO2, accounted for a range of about 48% to 90% of total ions in all the brands, whereas the respective percentages contribution of Cl ranged from 8% to 25%. Somewhat high percentage contributions up to 20% was observed for Ca2+, while Mg2+ was below 9%, and Fe2+ and NO were below 6%. The contributing source of SO2 in the bottled water brands could be from oxidation of sulphate containing ores such as gypsum whereas the observed Cl concentration in the bottled drinking water may come from water that entrapped in the sediments or from solutions of halite (chlorination process). The NO is undoubtedly
 
from natural occurring sources in addition to agricultural, industrial and domestic sources.  Table-1Classification based on EU mineral water directive Water type Criterion 
Very low mineral concentration Mineral content (TDS)  50 mg/l 
Low mineral concentration TDS 50-500 mg/l 
Intermediate mineral concentration TDS 500-1500 mg/l 
High mineral concentration TDS � 1500 mg/l 
Containing sulphate Sulphate � 200 mg/l 
Containing chloride Chloride � 200 mg/l 
Containing calcium Calcium � 150 mg/l 
Containing magnesium Magnesium � 50 mg/l 
Containing iron Bivalent iron � 1 mg/l 
Table-2 Classification of bottled drinking water brands based on TDS and total hardness Brand code A B C D E F 
TDS 8 37 113 126 122 54 
EU Class  Very low conc. Very low conc. Low conc. Low conc. Low conc. Low conc. 
Total Hardness 21.3 20 44 44 67 30 
Water class Soft water Soft water Soft water Soft water  Moderately hard water Soft water 
Conc. = Concentration Table-3  Chemical and physical parameters for the bottled drinking water brands and their comparison to the TBS and WHO limit values Brand code EC (s/cm) TDS (mg/l) Turbidity (NTU) 
A 17.4 7.8 1.0 
B 82.3 37.0 0.0 
C 251.0 113.0 0.0 
D 280.0 126.0 1.0 
E 270.0 121.5 0.0 
F 120.0 54.0 1.0 
Mean 170.1 76.6 0.5 
SD 111.5 50.2 0.5 
Minimum 17.4 7.8 0.0 
Maximum 280.0 126.0 1.0 
Median 185.5 83.5 0.5 
TBS   5-25 
WHO  500 5 
Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X  Vol. 2(7), 21-26, July (2012)   Res.J.Chem.SciInternational Science Congress Association 
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Correlation between various constituents: The correlation matrix for various water quality parameters in the bottled water brands during the survey is given in table 5. Most constituents exhibit strong correlations suggesting that they may originate predominantly from the same sources. Higher correlation (r � 0.80) was observed for alkalinity and pH, EC and hardness, between hardness and TDS, Mg2+; Fe2+ and Ca2+, and also between Mg2+ and SO2. As for the pH a strong correlation coefficient with EC (r = 0.69) and EC and TDS (r = 1.0) was found as shown in table 5, meaning that these constituents share the same source of high concentration of the major ions. High pH represents the major process controlling concentrations of the element in solution. Increase pH tends to increase concentration of Mg2+ and Fe2+ in solution, solubility of silicates mineral decrease solubility of calcium carbonate. High correlations among constituents with Ca2+ and SO2 suggest the dissolution of gypsum, besides; carbonate mineral weathering might be playing a role in the hydrochemistry of Ca2+ and water hardness. Table-4Concentrations of major constituents of bottled drinking water brands and their comparison to TBS and WHO limit values, The units are in mg/l except for pH Brand code pH Alkalinity Hardness Ca
2+
 Mg
2+
 Fe
2+
 Cl

 SO
4
2

 NO
3

 
A 7.4 32.0 21.3 8.5 0.1 0.20 2.5 28.5 0.2 
B 7.3 16.0 20.0 3.4 2.8 0.18 7.8 18.6 0.1 
C 7.6 79.0 44.0 9.4 5.0 0.19 10.1 28.5 3.5 
D 7.4 42.0 66.5 12.0 8.9 0.20 24.8 87.7 2.8 
E 7.5 48.0 44.0 14.0 2.2 0.22 48.2 5.9 0.3 
F 7.4 42.0 30.0 7.2 2.9 0.20 9.9 19.2 0.1 
Mean 7.4 43.2 37.6 9.1 3.6 0.02 17.2 31.4 1.2 
SD 0.1 20.8 17.6 3.7 3.0 0.01 16.9 28.8 1.5 
Minimum 7.3 16.0 20.0 3.4 0.1 0.18 2.5 5.9 0.1 
Maximum 7.6 79.0 66.5 14.0 8.9 0.22 48.2 87.7 3.5 
Median 7.4 42.0 37.0 9.0 2.9 0.20 10.0 23.9 0.3 
TBS 6.5-9.2  75-300 50-100 500-1000 0.3-1.0 200 200-800 10-25 
WHO 6.5-8.0     0.3 250 250 50 
Figure-1 Average concentrations of proportion of ionic constituents in difference bottled water brands 
4080120160ABCDEF
Ions concentrations (mg/l)
NO3
SO4
Cl
Fe
Mg
Ca
Research Journal of Chemical Sciences __________________________________________________________ ISSN 2231-606X  Vol. 2(7), 21-26, July (2012)   Res.J.Chem.SciInternational Science Congress Association 
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Figure-2  Percent attributions of major ions concentrations to bottled drinking water brandsTable-5  Correlation matrix for water quality paramters in the bottled drinking water brands    pH EC Alkalinity Hardness TDS Turbidity Ca Mg Fe Cl SO
4
 NO
3
 
pH 1.00            
EC 0.69 1.00           
Alkalinity 0.95 0.64 1.00          
Hardness 0.54 0.89 0.49 1.00         
TDS 0.69 1.00 0.64 0.89 1.00        
Turbidity -0.21 -0.30 -0.24 0.10 -0.30 1.00       
Ca 0.72 0.73 0.50 0.74 0.73 0.04 1.00      
Mg 0.22 0.71 0.31 0.86 0.71 0.12 0.30 1.00     
Fe 0.49 0.40 0.20 0.36 0.40 0.14 0.85 -0.13 1.00    
Cl 0.42 0.72 0.18 0.56 0.72 -0.31 0.79 0.19 0.78 1.00   
SO-0.02 0.35 0.03 0.71 0.35 0.52 0.25 0.83 -0.12 -0.04 1.00  
NO0.59 0.66 0.73 0.72 0.66 -0.09 0.34 0.78 -0.19 0.00 0.61 1.00 
Correlation coefficients that is larger than 0.50 are indicated in bold 
 
 
Brand ASO483%Cl7%Ca8%Mg0.4%Fe1%NO31%
Brand BCa10%Mg8%Fe1%Cl24%SO457%NO30.4%
Brand CCa17%Mg9%Cl18%SO450%NO36%Fe0.3%
Brand DSO464%Ca9%NO32%Fe0.1%Cl18%Mg7%
Brand FCa18%Mg7%Fe1%Cl25%SO449%NO30.4%
Brand ECl8%SO469%Ca20%Mg3%Fe0.3%NO30.4%
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ConclusionThis study gives an insight of major quality constituents of six bottled water brands currently sold in Mwanza retail shops. The results showed that the brands of bottled water analyzed are safe for human consumption. The measured constituents in the brands are within standards limits set by TBS and WHO for drinking water. However, the physicochemical quality of the brands studied was variable, which possibly depends on many factors such as natural environment, source water composition and type of treatment/purification technique(s) applied during the production. Additional changes in the water chemistries may also occur during storage and transportation, especially when bottles are exposed to direct sunlight. The number and type of parameters reported on the labels of bottled water showed a lack of homogeneity. Basic parameters (major ions) were usually indicated, whereas, for some brands generalized parameters were observed. In general, the concentration of species measured in this study was comparable to or slightly lower than values reported on the labels. This study has also shown that bottled water is not necessarily safer than tap water, and consumers should be aware.
 
Long-term consumption of waters low in minerals (e.g. calcium, magnesium and fluoride) may be responsible for important health problems. The study recommends regular need for a nationwide survey about the quality of waters including tap and river waters as well as groundwater. Additionally, the analysis and labelling of other parameters such as microbiological and arsenic for Tanzanian bottled drinking water brands is needed to protect public health.  Acknowledgment We acknowledge the financial support from Tanzania Higher Education Students' Loans Board (HESLB) and Sokoine University of Agriculture for granting special research fund to the first author. We express our sincere thanks to Mwanza Zonal Water Quality Laboratory for analysis of the water samples. References 1.Buchholz R.A., Principles of environmental management, The Greening of Business, 2nd. Prentice-Hall, London, UK, 448 (1998)  2.Gleick P.H., The world’s water, The Biennial Report on Fresh water Resources. Washington. Island Press (2006) 3.Lefort R., Down to the last drop, UNESCO Sources, No. 84(7) (2006) 4.World Health Organization (WHO), Guidelines for drinking water quality, Geneva WHO (2008)  5.United Republic of Tanzania (URT), Water Supply and Sanitation Act, Ministry of Water and Irrigation, Dar es Salaam (2009)6.Tredoux G. and Talma A.S., Nitrate pollution of groundwater in Southern Africa. In Groundwater Pollution in Africa, Xu Y, Usher B (eds), Taylor and Francis/Balkema: Leiden, The Netherlands, 15-36 (2006) 7.Eruola A.O., Ufoegbune G.C., Eruola A.O., Awomeso J.A. and Abhulimen S.A., Assessment of Cadmium, Lead and Iron in Hand Dug Wells of Ilaro and Aiyetoro, Ogun State, South-Western Nigeria, Res. J. Chem. Sci., 1(9), 1-5 2011)  8.Vaishnav M.M. and Dewangan S., Assessment of Water Quality Status in Reference to Statistical Parameters in Different Aquifers of Balco Industrial Area, Korba, C.G. India, Res. J. Chem. Sci.,1(9), 67-72 (2011) 9.Matini L., Tathy C. and Moutou J.M., Seasonal Groundwater Quality Variation in Brazzaville, Congo, Res. J. Chem. Sci., 2(1), 7-14 (2012) 10.Mjemah I.C., Hydrogeological and hydrogeochemical investigation of a coastal aquifer in Dar-es-Salaam, Tanzania. PhD Thesis, Ghent University, 222 (2007) 11.Kassenga G.R. and Mbuligwe S.E., Comparative Assessment of Physicochemical Quality of Bottled and Tap Water in Dar Es Salaam, Tanzania, Int. J. Biol. Chem. Sci.,3(2), 209-217 (2009) 12.Kibona I., Mkoma S.L. and Mjemah I.C., Nitrate pollution of Neogene alluvium aquifer in Morogoro municipality, Tanzania, Int. J. Biol. Chem. Sci., 5(1), 171-179 (2011) 13.Tanzania Food and Drugs Agency (TFDA), Tanzania Food, Drug, and cosmetic Act No.1 of 2003, Tanzania, TFDA, (2003) 14.Tanzania Bureau of Standards (TBS), National Environmental Standards Compendium: TZS 789. Drinking (potable) water – Specification, 74, (2005) 15.Kassenga G.R., The Health-Related microbiological quality of bottled drinking water sold in Dar-Es-Salaam, Tanzania, J. Water Health, 5(1), 179-185 (2007) 16.Oyedej O., Olutiola P.O. and Moninuola M.A., Microbiological quality of packaged drinking water brands marketed in Ibadan metropolis and Ile-Ife cities in South Western Nigeria, Africa J. Microbiol. Res., 4(1), 96-102 2009) 17.Energy and Water Utilities Regulatory Authority (EWURA), Performance of Water Supply and Sewerage Authorities for 2008/9 (2010)  18.Vander Aa N.G.F.M., Classification of mineral water types and comparison with drinking water standards, Environ. Geol., 44, 554-563 (2003)  19.Birke M., Rauch U., Harazim B., Lorenz H. and Glatte W., Major and trace elements in German bottled water, their regional distribution, and accordance with national and international standards, J. Geochem. Explor.,107(3), 245-271 (2010) 
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