Bacterial Water Quality in the
Personal Water Bottles of
M.C. Ryan, PhD, PGeol, PEng
A. Chu, PhD
Background: Samples of drinking water were collected directly from the personal water
bottles of students at an elementary school in Calgary, Alberta.
Methods: Total and fecal coliforms and heterotrophic bacteria were enumerated using
membrane filtration and agar plate count methods respectively.
Results: The Canadian Drinking Water Quality Guidelines (CWQG) criterion was
exceeded for total coliform in 13.3% of 75 samples. Fecal coliform and total heterotrophic
criteria were exceeded in 8.9% (of 68 samples) and 64.4% (of 76 samples) respectively.
Findings: The use of personal water bottles for students in elementary classrooms is not
ersonal water bottles are commonly
used in schools and in the work-
place. An elementary school in
Calgary, Alberta recommended that stu-
dents keep personal water bottles at their
desks throughout the school day. In the
absence of official instruction regarding
bottle washing, some students brought
clean water bottles on a daily basis, while
others continually refilled the same water
bottle for months without washing it. The
objective of this study was to assess the
bacteriological water quality in personal
water bottles taken from the desks of stu-
dents at this school in Calgary.
Sampling was conducted to collect repre-
sentative samples of water that the students
were drinking. Any available water present
in an individual student’s water bottle was
transferred into sterile (autoclaved at
C for 20 minutes) polypropylene bot-
tles for lab analysis. Three separate class-
rooms were sampled over a one-week peri-
od. In total, 76 samples were collected
directly from student water bottles, with
sample volumes ranging from 10 to 500
mL. In addition, source water samples
were collected from each of thee classroom
sinks and two drinking water fountains
located in the school hallways. All water
samples were stored at 4°C and analyzed
within 18 hours of collection.
Heterotrophic bacteria were quantified
using Heterotrophic Plate Counts (HPC)
on standard HPC plate count media.
Coliform bacteria were analyzed using
Standard Membrane Filtration (MF)
techniques and m-Endo (total coliform)
and m-FC (fecal coliform) media.
Significant levels of coliform bacteria were
found in water from the students’ personal
water bottles (Table I). Of the 76 samples
analyzed for total coliforms, 10 (13.3%)
contained >10 cfu/100mL. Fecal coliforms
were enumerated at >1 cfu/100mL in 6 of
68 samples analyzed (8.9%).
Heterotrophic bacteria concentrations
were also elevated. Heterotrophic plate
counts are used as an overall indicator of
the bacterial quality of water supplies.
Drinking water guidelines (>500 cfu/mL)
were exceeded in water collected from
La traduction du résumé se trouve à la fin de l’article.
1. Department of Civil Engineering, University of Calgary, Calgary, AB
2. Department of Geology and Geophysics, University of Calgary
Correspondence and reprint requests: M.C. Ryan, Department of Geology and Geophysics,
University of Calgary, Calgary, AB T2N 1N4, Tel: 403-220-2739, Fax: 403-284-0074, E-mail:
Acknowledgements: The authors thank the elementary school participating in this study, and Dr. T.
Lambert of the Environmental Health Division, Calgary Regional Health Authority, for his assistance
in water sampling.
366 REVUE CANADIENNE DE SANTÉ PUBLIQUE VOLUME 93, NO. 5
SEPTEMBER – OCTOBER 2002 CANADIAN JOURNAL OF PUBLIC HEALTH 367
ELEMENTARY STUDENTS’ WATER QUALITY
64.4% of the bottles. These high het-
erotrophic counts may indicate the effect
of bacterial regrowth in bottles that have
remained at room temperature for an
extended period. Significant bacterial
regrowth has been shown to occur in treat-
ed, chlorinated water, when left at ambient
temperature for as little as 8-24 hours.
Bacterial levels from each of the five
source water samples were all under the
detection limits for both coliforms (i.e.,
<1 cfu/100mL) and heterotrophs
The findings suggest that significant bacte-
rial contamination can occur in individual
water samples originating from personal
water bottles. This study cannot identify
the origin of contamination, however the
most likely source of enteric bacteria found
in the students’ water bottles is the hands
of the students themselves. Inadequate and
improper hand washing after students have
used the bathroom facilities could result in
fecal coliforms in the classroom area. A
study conducted within a Houston, Texas
day-care isolated fecal coliforms from the
hands of 17% of staff and children, and
13% of classroom objects during routine
These rates increased signifi-
cantly during outbreaks of diarrhea.
Although the transmission routes of fecal
contamination in day-care centres may
vary from those in primary schools, conta-
mination of hands, taps and sinks was
shown to be a reliable predictor of diar-
These same sources may
potentially be the main vectors of fecal
transmission from the environment to the
students’ water bottles in this study. A pre-
vious study conducted in a primary school
in Leeds, England indicated that hygiene
training significantly decreased the levels of
fecal streptococci isolated from the hands
of elementary children.
obtained from this study suggest there is a
need to educate students about proper
hygiene practices in order to decrease the
spread of coliform bacteria.
Significant bacterial contamination
occurred in water collected from personal
water bottles. Since the source water
showed no significant levels of het-
erotrophic or coliform bacteria, we con-
clude that current practices pertaining to
personal water bottle care at this elemen-
tary school are not sufficient to ensure the
safe bacterial quality of the students’ drink-
ing water. Drinking directly from the
water fountains may be a safer alternative
to water bottles.
Further study with larger sample popula-
tions and sample replication is warranted
to further evaluate the risk of reusing per-
sonal water bottles.
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BJ, Hawkins CM. Transmission dynamics of
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4. Laborde DJ, Weigle KA, Weber DJ, Kotch JB.
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Received: June 28, 2001
Accepted: April 29, 2002
Summary of Results from the Bacteriological Analysis of Water from Elementary
Students’ Personal Water Bottles
Coliform Bacteria Heterotrophic plate counts
(cfu/100mL) (HPC) (cfu/mL)
Range Frequency (% Samples)* Range Frequency
<1 85.3 91.2 <10 15.8
1-10 1.3 1.5 10-500 19.7
11-100 0‡ 1.5 501-5,000 7.9
101-1,000 4.0 1.5 5,001-50,000 11.8
>1,001 9.3 4.4 >50,000 44.7
Maximum 22,300 16,800 – >400,000
# Samples 75 68 – 76
CWQG† 00 – <500
Total % exceeding CWQG† 13.3 8.9 – 64.4
* Frequency values rounded to nearest tenth of a percent
† Microbiological criteria in the Canadian Drinking Water Quality Guidelines (CWQG; which can
be viewed at http://www.hc-sc.gc.ca/waterquality) recommend a maximum criteria of zero total
coliform detectable per 100 mL, but tolerate up to 10 total coliform detectable per 100 mL in
recognition of sample variability. A guideline of less than 500 HPC is set because of possible
coliform inhibition, not necessarily because the heterotrophic bacteria themselves are pathogen-
‡ bolded values exceed Canadian Water Quality Guidelines (CWQG)
Contexte : Nous avons recueilli des échantillons d’eau potable dans les gourdes à eau des élèves
d’une école primaire de Calgary (Alberta).
Méthode : Par filtration sur membrane et au moyen de tests sur plaque à la gélose, nous avons
déterminé le nombre total de bactéries et le nombre de coliformes fécaux et de bactéries
Résultats : Le seuil fixé dans les Recommandations pour la qualité de l’eau potable au Canada eu
égard au nombre total de coliformes a été dépassé dans 13,3 % des 75 échantillons recueillis. Le
seuil pour les coliformes fécaux a été dépassé dans 8,9 % des cas (sur 68 échantillons), et celui
pour l’ensemble des bactéries hétérotrophes, dans 64,4 % des cas (sur 76 échantillons).
Constatations : L’emploi de gourdes à eau par les élèves du primaire est à éviter.