210 Modern Food Microbiology
BOTTLED WATER
“Water that is vended in a bottle” is a very simple yet incomplete definition of bottled water as it
exists in commerce. It is defined by the Codex Alimentarius Commission, the European Economic
Community (Council Directive for Potable Waters), and regulated in most countries by the same body
that regulates foods. The most common bottled waters fall into one of the following groups (extracted
from references 21, 29):
Natural mineral water (eaux plates or “flat waters” in Europe)
Naturally carbonated natural mineral water
Non-carbonated natural mineral water
Carbonated natural mineral waters
Ground water
Spring water
However classified, bottled water must be potable, which means it must be free of pathogens, toxic
substances, objectionable odor, color, turbidity, or taste (see reference 21). The pH of non-carbonated
water should be around neutrality, whereas that of carbonated water is typically between 3 and 4.0—
ideally at or below pH 3.5.
In general, the microbiology of drinking water is complex, and this subject has been reviewed by
Szewzyk et al.
59 Although bottled waters are generally free of intestinal pathogens that persist in the
drinking water supply, Legionella pneumophila (causes legionellosis) has been shown to survive for
months in sterile drinking water (see reference 59). The safety of bottled water is determined by testing
for coliforms—not specific fecal coliforms or E. coli. However, if a fecal coliform test is run, the WHO
recommendation of 1993 is for <1 cfu/100 ml. When tested by the membrane filter method, not more
than 3 coliforms/100 ml should be present. APC determinations on bottled water are of little value
in determining safety since the numbers should not exceed 10
2 /100 ml. Because of the destructive
effects of the low pH of carbonated bottled water, testing for coliforms is not necessary.
The types of organisms that are found in potable bottled water consist of Gram negatives since they
are so much more synthetic than Gram positives, and thus, can survive on traces of organic matter.
Pseudomonads are not unknown among this group, and the presence of P. aeruginosa or Burkholderia
cepacia is of special concern in bottled water because of the infectious nature of these organisms for
debilitated individuals. The presence of organisms of this type is minimized by the use of ozone in
the bottled water industry. The FDA in the United States approved in 1997 ozonation at a maximum
level at the time of bottling of 0.4 ppm.
29
Results from various investigators on the presence of E. coli and other coliforms; and the fate of
inoculated E. coli 0157:H7 in bottled waters are varied. An analysis of 104 brands of bottled waters
from 10 countries failed to detect either E. coli or coliforms.
16 In another study on noroviruses (see
chapter 31), none could be found in 1,436 analyses of bottled water in different sized containers
although by RT-PCR, 34 (2.4%) were presumptively positive but by DNA sequence analysis, they did
not confirm.
32 E. coli 0157:H7 was shown to survive for >300 days when a 10-strain mixture was
added at levels of log 10 3.24– 6.54 cfu/ml to bottled spring and mineral waters.
63 These investigators
presented evidence for biofilm formation by the inoculated organisms on the sides of containers.
Previous investigators found that E. coli numbers were reduced by 3 to 5 logs in mineral water held
at 20 to 25
◦ C.
In a detailed study with a nontoxigenic strain of E. coli 0157:H7 added to three types of bottled
natural and noncarbonated mineral waters at levels of 10
3 and 10
6 cfu/ml and stored at 15
◦ C for 10
weeks, no differences were found between cell survival in natural noncarbonated and sterile natural
BOTTLED WATER
“Water that is vended in a bottle” is a very simple yet incomplete definition of bottled water as it
exists in commerce. It is defined by the Codex Alimentarius Commission, the European Economic
Community (Council Directive for Potable Waters), and regulated in most countries by the same body
that regulates foods. The most common bottled waters fall into one of the following groups (extracted
from references 21, 29):
Natural mineral water (eaux plates or “flat waters” in Europe)
Naturally carbonated natural mineral water
Non-carbonated natural mineral water
Carbonated natural mineral waters
Ground water
Spring water
However classified, bottled water must be potable, which means it must be free of pathogens, toxic
substances, objectionable odor, color, turbidity, or taste (see reference 21). The pH of non-carbonated
water should be around neutrality, whereas that of carbonated water is typically between 3 and 4.0—
ideally at or below pH 3.5.
In general, the microbiology of drinking water is complex, and this subject has been reviewed by
Szewzyk et al.
59 Although bottled waters are generally free of intestinal pathogens that persist in the
drinking water supply, Legionella pneumophila (causes legionellosis) has been shown to survive for
months in sterile drinking water (see reference 59). The safety of bottled water is determined by testing
for coliforms—not specific fecal coliforms or E. coli. However, if a fecal coliform test is run, the WHO
recommendation of 1993 is for <1 cfu/100 ml. When tested by the membrane filter method, not more
than 3 coliforms/100 ml should be present. APC determinations on bottled water are of little value
in determining safety since the numbers should not exceed 10
2 /100 ml. Because of the destructive
effects of the low pH of carbonated bottled water, testing for coliforms is not necessary.
The types of organisms that are found in potable bottled water consist of Gram negatives since they
are so much more synthetic than Gram positives, and thus, can survive on traces of organic matter.
Pseudomonads are not unknown among this group, and the presence of P. aeruginosa or Burkholderia
cepacia is of special concern in bottled water because of the infectious nature of these organisms for
debilitated individuals. The presence of organisms of this type is minimized by the use of ozone in
the bottled water industry. The FDA in the United States approved in 1997 ozonation at a maximum
level at the time of bottling of 0.4 ppm.
29
Results from various investigators on the presence of E. coli and other coliforms; and the fate of
inoculated E. coli 0157:H7 in bottled waters are varied. An analysis of 104 brands of bottled waters
from 10 countries failed to detect either E. coli or coliforms.
16 In another study on noroviruses (see
chapter 31), none could be found in 1,436 analyses of bottled water in different sized containers
although by RT-PCR, 34 (2.4%) were presumptively positive but by DNA sequence analysis, they did
not confirm.
32 E. coli 0157:H7 was shown to survive for >300 days when a 10-strain mixture was
added at levels of log 10 3.24– 6.54 cfu/ml to bottled spring and mineral waters.
63 These investigators
presented evidence for biofilm formation by the inoculated organisms on the sides of containers.
Previous investigators found that E. coli numbers were reduced by 3 to 5 logs in mineral water held
at 20 to 25
◦ C.
In a detailed study with a nontoxigenic strain of E. coli 0157:H7 added to three types of bottled
natural and noncarbonated mineral waters at levels of 10
3 and 10
6 cfu/ml and stored at 15
◦ C for 10
weeks, no differences were found between cell survival in natural noncarbonated and sterile natural