Indian Journal of Dental Research

ORIGINAL RESEARCH
Year
: 2010  |  Volume : 21  |  Issue : 4  |  Page : 515--517

Fluoride and bacterial content of bottled drinking water versus municipal tap water


H Mythri1, GN Chandu1, GM Prashant1, VV Subba Reddy2,  
1 Department of Community Dentistry, College of Dental Sciences, Davangere, Karnataka, India
2 Department of Paedodontics, College of Dental Sciences, Davangere, Karnataka, India

Correspondence Address:
H Mythri
Department of Community Dentistry, College of Dental Sciences, Davangere, Karnataka
India

Abstract

Background: Water is a divine gift. People quench their thirst without questioning the source of water. But, apprehension about contaminants in municipal water supplies along with increased fear of fluorosis made bottled drinking water as one of the important tradable commodities. Objectives: The objectives of the study were to determine and compare the fluoride and bacterial contents of commercially available bottled drinking water and municipal tap water in Davangere city, Karnataka. Materials and Methods: Fifty samples of 10 categories of bottled drinking water with different batch numbers were purchased and municipal water from different sources were collected. Fluoride levels were determined by an ion-selective electrode. Water was cultured quantitatively and levels of bacteria were calculated as colony-forming units (CFUs) per milliliter. Results: Descriptive analysis of water samples for fluoride concentration was in the range of 0.07-0.33 for bottled drinking water, Bisleri showing the highest of 0.33. A comparison of the mean values of microbial count for bottled drinking water with that of municipal tap water showed no statistically significant difference, but was more than the standard levels along with the presence of fungus and maggots. Conclusion: The fluoride concentration was below the optimal level for both municipal tap water and bottled drinking water. CFUs were more than the recommended level in both municipal tap water and bottled drinking water.



How to cite this article:
Mythri H, Chandu G N, Prashant G M, Subba Reddy V V. Fluoride and bacterial content of bottled drinking water versus municipal tap water.Indian J Dent Res 2010;21:515-517


How to cite this URL:
Mythri H, Chandu G N, Prashant G M, Subba Reddy V V. Fluoride and bacterial content of bottled drinking water versus municipal tap water. Indian J Dent Res [serial online] 2010 [cited 2021 Sep 23 ];21:515-517
Available from: https://www.ijdr.in/text.asp?2010/21/4/515/74223


Full Text

Water is a divine gift. Since long, people quenched their thirst without questioning the source of water. The source of municipal water for Davangere city is the Tungabadra River and the Lakvalli dam (channel).

The major water is supplied by two water plants (one is situated near TV Station, the source of raw water being the Lakvalli dam [channel] and another is in Doddabathi, where the source of raw water is from the Tungabadra river), which serve more than a 3,62,780 population (2001 census data). The process of water purification at the water plants is similar to the process used in most of the water plants, consisting of many intricate steps and including theuse of chemicals and filters (rapid sand filtration technique). [1] But, apprehension about contaminants in municipal water supplies along with increased fear of fluorosis made bottled drinking water as one of the most important tradable commodities. Fluoride levels in tap water differ substantially from the fluoride levels in bottled water.

Objectives

The objectives of the study were to determine and compare the fluoride and bacterial contents of commercially available bottled drinking water and municipal tap water in Davangere city, Karnataka.

 Materials and Methods



The study was conducted during the period July 2008 to February 2009, and 50 samples of 10 categories of bottled drinking water with different batch numbers were purchased from different stores to capture the total market. Samples of tap water were collected in 100 ml sterile containers from the two local water-processing plants. After receiving permission to obtain water samples from the two water plants, six water samples from each plant on unannounced visits were collected - three raw water samples and three immediately after purification. The quality of tap water collected outside the water plant, e.g. at a residence or business, could be altered by residential or commercial plumbing or filtration systems. Hence, in order to compare, six samples from different end point sources were collected.

All water samples were transported to the Department of Chemical Engineering, Bapuji Institute of Engineering and Technology, and Department of Oral Pathology, College of Dental Sciences, Davangere, for fluoride and microbial analysis, respectively. All the samples were given a code by an investigator and the laboratory technicians were blinded to the type of water contained in the samples in order to avoid any potential bias.

Fluoride levels were determined by an ion-selective electrode (Orion 94-09). Water was cultured quantitatively and the levels of bacteria were calculated as colony-forming units (CFUs) per milliliter after incubating in Blood agar at 37°C for 2 days.

Following descriptive analysis, statistical analysis was performed using unpaired Student's t-test and a P-value <0.05 was considered to be statistically significant.

 Results



[Table 1] shows the fluoride concentration of different packaged drinking bottles. The mean concentration of fluoride was different in different brands, with the highest fluoride concentration in bisleri (with a concentration of 0.33 ppm) and the lowest fluoride concentration in flair (with a concentration of 0.10 ppm). Among municipal water, the fluoride concentration varied from 0.06 to 0.11. [Table 2] shows a comparison of the mean values of bottled drinking water and municipal water showed a highly significant difference, but both were below the optimum levels (0.7-1.2 ppm) of fluoride.{Table 1}{Table 2}

[Table 3] shows that the microbial analysis of bottled drinking water varied from 13.5 to 183 CFU/ml, Riwa showing the highest and one sample from Flair (batch no. August 30/2008) showing the presence of fungus and maggots. The municipal water samples collected before and at the end point sources showed the presence of maggots and fungus, whereas they were absent immediately after purification. [Table 4] shows that a comparison of the mean values of microbial count for bottled drinking water with that of municipal tap water showed no statistical significant difference, but was more than the standard levels. [Figure 1] shows the microbial analysis of water from two water plants at different phases. {Table 3}{Table 4}{Figure 1}

 Discussion



Results of the present study showed that fluoride in bottled drinking water was less than the optimum level [0.7-1.2], which was similar to the studies conducted by Zohouri et al., [2] Toumbia et al., [3] and Thippeswamy et al. [4] Among the bottled drinking water, Bisleri showed the maximum concentration in a study by Thippeswamy et al., which was similar to the results of the present study.

For microbial analysis, WHO (1993 and 1996) [5] recommended that CFUs/ml should be 0 after 2 days at 37°C (if water is disinfected) or 10 (if water is not disinfected) and Barrell [6] has reported 20 CFU/ml within 12 h of bottling when colony count 37°C/48 h can be accepted. In the present study, few samples of water at the end point source showed an increase in the CFUs, which can be explained due to water contamination in pipelines during distribution. Overall, CFU counts were higher in municipal as well as in bottled drinking water. The CFU count was higher than the recommended level in bottled drinking water, which was similar to the studies conducted by Payment et al., [7] Mavridou et al., [8] Hunter [9] and Silva et al. [10] But, there was no statistical difference among bottled drinking water and that of municipal tap water in the present study, which was similar to the study conducted by Payment et al. [7] This was in contrast with the studies conducted by James [1] and Silva et al., [10] where municipal water showed a lower CFU count than bottled drinking water.

Along with CFUs, few samples of municipal tap water (raw water and water at the end point) and one sample of bottled drinking water (Flair, batch no. August 30, 2008) showed the "presence of maggots." Maggot is the common name of the larval phase of development in insects of the order Diptera (flies). This was similar to a Charles Cooper report, where people complained of finding Rat Tailed Maggot in the municipal water supplies of different parts of Cape Town (South Africa) in April 2006. [11] This can be explained due to the process of "Back siphoning."

In the literature, there were outbreaks of Giardiasis due to groundwater contamination (Craun et al., 1986) and an outbreak of cholera in Portugal in 1974 due to the consumption of contaminated bottled drinking water (Blake et al., 1977). [1] All these evidences show a clear evidence of potential contamination of municipal and bottled drinking water, which was similar to the results of the present study.

 Conclusions





Fluoride concentration was below the optimal level for both municipal tap water and bottled drinking water.CFUs were higher than the recommended levels in both municipal tap water and bottled drinking water.Despite the presence of maggots in municipal water, evidence of potential adverse health effects were lacking; hence, further epidemiological studies (longitudinal) are recommended.But, people cannot survive without water and hence one should choose whether to drink bottled water or tapwater on cost or taste, not on presumed health grounds. But, in places with main water of uncertain quality, bottled drinking water can be a safer alternative.

 Recommendations





The public should be made aware of the factors affecting their health by providing health education.Monitoring or regulating the optimal range of fluoride in tap water as well as in bottled drinking water should be recommended.Strict regulations on the labeling of fluoride contents of bottled waters.Regular surveillance as well as monitoring of water-treatment plants, pipelines, end source and bottled drinking water to meet the required microbial standards is recommended.

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