Groundwater in the Great Lakes Basin

Infection of a suitable host species results from ingestion
of the parasite in its transmissible stage, the oocyst
that is hardy and persists in the environment for weeks.
The illness, cryptosporidiosis, consists of watery
diarrhea and, occasionally, vomiting. Diarrhea typically
lasts for 10 to 14 days in people and cattle, but may last
for several months. No treatment is available.
Disinfection – A water treatment specifically designed
to destroy or inactivate pathogenic organisms and
thereby prevent waterborne diseases, which are the
most significant health risk associated with drinking
water. Primary disinfectants are added to disinfect the
water before it enters the water supply distribution
system. Secondary disinfectants are used to prevent
regrowth of bacteria in the distribution system.
Commonly used disinfecting agents are chlorine and
related chloramine compounds; there is increasing
interest in the use of ozone as a primary disinfectant.
Considerations in choosing disinfectants include
disinfecting power, cost of use and effects on taste and
odour of drinking water. Minimizing by-products associated
with disinfectant use is also a concern. Some byproducts
are possibly carcinogenic, although research
findings are not clear.
Disinfection by-products – Secondary chemicals
produced when a disinfectant reacts with organic matter
in water. For example, when chlorine is added to water,
it reacts with organic matter to form trihalomethanes.
Because they are formed from chlorine, trihalomethanes
are referred to as “chlorinated disinfection by-products.”
If water is treated to remove the organic matter prior to
disinfection, such as through filtration, a lesser amount
of by-product will be formed.
Distribution system – The pressurized piping system
that carries water from a drinking water treatment
facility to the premises of consumers.
Drinking water officer – A specialized health professional.
In British Columbia, the drinking water officer
is the medical health officer, but the latter can delegate
duties to another qualified person. For more information,
see www.health.gov.bc.ca/protect/dwoguide.pdf .
E. coli (Escherichia coli) – A type of fecal coliform bacteria
whose presence in water indicates recent animal
contamination and the possible presence of pathogenic
microorganisms. The test for E. coli is the “Gold
Standard” method for identifying fecal contamination.
Endemic Disease – An infectious disease that is
present in the community at all times but normally at
low frequency.
Epidemic Waterborne Disease – Any infectious
disease that develops and spreads rapidly to many
people.
Fecal coliforms – A sub-group of coliforms found
almost exclusively in the intestinal wastes of humans
and animals, but capable of growing elsewhere in the
environment. If found in water, they are an indicator
that it has been contaminated with sewage or other
intestinal wastes
and may be a potential risk, if containing diseasecausing
organisms. Water containing fecal coliforms is
generally unsafe to drink. See E. coli.
Freshet – The flood of a river from heavy rain or snow
melt.
Giardia – A protozoan parasite found widely in many
mammalian intestines. Infection with Giardia – an
illness called giardiasis, inappropriately nicknamed
“beaver fever” – can cause diarrhea, abdominal cramps,
nausea or vomiting, weight loss and fatigue lasting
many weeks. It can be carried by humans as well as by
certain domestic and wild animals.
Groundwater – Water found underground in the
saturated zone of an aquifer. Groundwater is a source
of well water and often surface water (e.g., springs).
Guidelines for Canadian Drinking Water Quality
– A comprehensive compilation of recommended
limits for substances and conditions that affect the
quality of drinking water, developed by the Federal-
Provincial-Territorial Committee on Drinking Water
and published by Health Canada. Available at www.
hc-sc.gc.ca/waterquality.
Health hazard – In relation to drinking water, a condition
or thing that endangers public health or prevents
or hinders the prevention or suppression of disease.
Also, a prescribed condition or thing that fails to meet a
prescribed standard.
Mandatory standards – Conditions that water quality
is legally required to meet in order to be considered
potable.
Membrane filtration – A technique that permits
removal of particles from a drinking water source on
the basis of their molecular size and shape with the
use of pressure and specially designed semi-permeable
membranes.
Meninges (Singular – menynx) – Membranes covering
the brain and the spinal cord.
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