STATE OF THE GREAT LAKES 2005
CAN WE DRINK THE WATER?
Yes, current water treatment technologies ensure the high quality of our drinking water.
The Issues
Every day, millions of people drink treated water
that comes from the lakes, rivers and wells of the
Great Lakes region. For decades, these sources
have been subjected to pollution, threatening the
purity of the water for consumption.
The greatest threat to drinking water comes from
bacteria, viruses and parasites found in human
and animal wastes as well as from chemical
contamination. These pollutants frequently enter
lakes, rivers and groundwater through
contaminated runoff as a result of heavy rainfall.
When ingested by humans they may cause
illness, including gastrointestinal distress, which
can be fatal in severe cases.
While technology allows municipalities to treat
water to make it free from dangerous levels of
contamination, it is important to realize that the
quality of source water, such as lakes, rivers,
streams or reservoirs, will impact the level of
treatment necessary to make the water safe to
drink.
The Indicator
Testing of both source and treated water serves to
assess the potential for human exposure to drinking
water contaminants and the effectiveness of policies
and technologies to ensure safe drinking water. This
report focuses on treated water.
Drinking water quality has been assessed using data
from various treatment facilities across the region.
Assessments are based on information from these
major treatment facilities only. Several drinking water
parameters are monitored, including:
Atrazine: an agricultural herbicide.
Nitrate and nitrite: derivatives of nitrogen, they
are naturally occurring nutrients that are found at
high levels in fertilizers.
Total coliform, E. coli, Cryptosporidium and
Giardia: disease-causing organisms that can
contaminate water supplies.
Turbidity and organic carbon (total or dissolved):
these parameters do not pose a direct threat to
human health, but are often indicative of health
hazards, as they can absorb, bond or react with
toxic substances and provide nutrients for
bacterial growth.
Taste and odour: attributed to natural
compounds released by algae during warmer
months, and can affect consumer perception of
drinking water quality. Potential health hazards
related to algae are currently being studied.
Locations of water treatment plants (United States) and
drinking water systems (O Canada) in the Great Lakes
region, assessed in this report. Source: State of the Great
Lakes 2005 report.
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WE DRINK THE WATE...
The Assessment
Chemical contaminants
Atrazine, nitrate and nitrite are commonly detected
in source and treated water. Although atrazine
levels were highest in treated water samples where
the water source was located in an agricultural
watershed, there were no occasions in 2001 and 2002
when the levels exceeded drinking water standards
set by Canada or the United States.
Nitrate is considered a reoccurring contaminant,
because it is commonly detected in both source and
treated water, while nitrite is rarely detected in
treated water. Nitrate in treated water was not
detected above drinking water standards at the
facilities surveyed in 2001, and only one water
treatment plant violated drinking water standards
for nitrate in 2002. Nitrite was never detected in
treated water above drinking water standards in
2001 and 2002.
Microbiological contaminants
This contamination occurs predominantly in source
water; however, inadequate treatment technologies
or contamination post-treatment may result in its
presence in drinking water. Information from water
facilities within the Great Lakes region used in this
report show that, while these micro-organisms were
detected in source water across the basin, at no
point did their concentrations in treated water
exceed standards in 2001 and 2002. The presence of
these contaminants in source, but not treated, water
indicates that current treatment techniques are
effective at removing them from drinking water.
Other compounds
Total organic carbon was detected in treated water
samples from all sources except those using source
water from lakes Huron and Superior. Dissolved
organic carbon was detected in Ontario, but never
exceeded the established objectives or standards.
Bad taste and odour complaints were recorded
during the summer months of 2001 and 2002. These
occurrences were attributed to natural compounds
Photo: EnvironmentCanada.
released by algae during warmer weather.
Current Actions
Both the Great Lakes states and Ontario actively
conduct source water assessment and protection
measures. The results of the assessments are
published in the annual Consumer Confidence and
Water Quality Reports in the United States and annual
reports from the drinking water systems in Ontario.
Actions Needed
Implementing measures to prevent or reduce chemical
and microbial contamination from source waters must
remain a priority. High-quality source water reduces
the costs associated with treating water promotes a
healthier ecosystem and lessens potential contaminant
exposure to humans.
Standardized reporting on the status of drinking
water, including the analysis of source versus treated
water, needs to be developed in order to improve the
assessment of the potential human health risks from
drinking water.
To Learn More
For further information about the quality of Great
Lakes drinking water, refer to the State of the Great
Lakes 2005 report which, along with other Great
Lakes references, can be accessed at
www.epa.gov/glnpo/solec.
02/06
EPA 905-F-05-003
IISG-05-09
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