| Pathogens
and Your Well Water
What’s in your
well’s water, besides water?
Only test results that are carried out by the public health laboratory or a
private laboratory can tell you for sure.
When you submit your well water to the public health laboratory or a private
laboratory for testing, it will be analyzed for the presence of “pathogens.”
Pathogens are organisms that cause illness in humans. When it comes to well water,
pathogens of concern include certain forms of bacteria, protozoa and viruses. While
each of these organisms can lead to different illnesses of varying severity, there
are some very unpleasant symptoms common to many, including diarrhoea, nausea,
abdominal cramps and low-grade fevers.
Here’s the take-home message: your well is your first line of defence against
harmful organisms reaching your water supply. Maintain your well regularly and
thoroughly – it’s easier to prevent problems than to fix them. To complete your
well water safety routine, get your water tested regularly.
Three uninvited guests: bacteria, protozoa, and viruses
Bacteria are a natural part of life. In fact, there are many forms and functions of
bacteria we couldn’t live without, such as those that break down organic matter
(e.g., food waste, leaves). Water is a preferred environment for bacteria because
their membranes could otherwise dry out. But some bacteria in water can lead to
serious illness or disease, such as gastroenteritis or salmonellosis. These days, E.
coli O157:H7 is probably the most infamous disease causing bacteria.
Some protozoa can live in animals and humans, and are passed in feces. These tiny
parasites are able to survive in surface water for long periods of time as dormant
cysts. Some waterborne protozoa can cause illness, such as giardiasis or
cryptosporidiosis. Viruses reproduce by infecting living cells. Some viruses found
in water cause illness, including Hepatitis A and the Norwalk virus.
Protozoa and viruses are usually found only in surface water that has been
contaminated by animal or human feces. However, groundwater can become contaminated
through contact with surface water. In other words, if surface water can penetrate
any unsealed joint or crack anywhere in your well, your water is at risk.
More
about E. coli
The most harmful pathogen is Escherichia coli (or E. coli) O157:H7. It’s
spread through contaminated food (such as undercooked hamburger) and water.
Symptoms may include stomach cramps, vomiting, fever and diarrhoea. Severe
cases can progress to kidney failure in the elderly and children. Early
symptoms are common to a number of diseases, and may or may not be the result
of contaminated drinking water. Contact your doctor for more information.
Although E. coli O157:H7 can cause serious illness, most of the other hundreds
of E. coli strains are harmless, and some are even beneficial. In fact, E.
coli make up part of the natural flora – bacteria that live in your large
intestines. |
To
the top
How pathogens move
through and survive in soil
As described in Get Acquainted with Your Well,
when surface water travels down through soil to groundwater, it can take harmful
pathogens with it. Fortunately, soils can have a cleansing effect on harmful
pathogens. But if they are able to bypass soils’ natural cleansing action,
pathogens can survive. Bypass routes can introduce human and animal wastes into
groundwater by reducing the time and distance it takes to travel through soils. The
shorter the travel time, the greater the risk of contamination.
Have you built an expressway for pathogens?
Some of the facilities or activities on your property might be providing pathogens
with these bypass routes. A well that’s poorly constructed or plugged provides one
route. An onsite septic system that’s improperly or poorly designed, maintained or
located provides another. Weather can also create a bypass route. Very heavy rains
or flooding can move contaminants through soil at faster rates than normal.
 |
The
arrows show the pathways that pathogens can follow to get into an improperly
constructed, shallow well. The red shading indicates the “annular space,”
which is the space outside the well casing that was created when the hole for
the well was made. In this well, the annular space is unsealed at the top, and
acts as a duct for contaminated surface water to pass down into the well
intake at the bottom. To make matters worse, contaminated surface water can
also enter the well through unsealed tile joints and cracks. |
To
the top
Is your well
playing host?
Get in the habit of putting your well water to the test. How do you know if your
well water is playing host to unwanted organisms? Regular testing of your well water
is the best way. Test your well water
regularly. Three times per year – in Spring, Summer and Fall – is recommended.
Routine testing also provides an early warning signal of potential problems.
Some water-testing lingo
When drinking water is tested for biological (as opposed to chemical) contamination,
the bacteria that are tested for are called indicator organisms or indicator
bacteria. The presence of indicators acts as an early warning signal. It tells you
there are health risks with your well water. The indicator bacteria usually show up
in a test if your water has become contaminated with surface water.
There are two indicator organisms that public health labs will test for when you
submit a sample. These are Total coliform and E. coli.
Total coliform (or T.C.)
- are a general family of bacteria that is found in animal wastes, surface soils
and vegetation
- indicate contamination of water with organisms, and possible evidence of
surface water contamination in your well water
- provide an early warning signal that there may be a problem with your water
supply
E. coli
- are a group of bacteria that live in the intestines of warm-blooded animals
- indicate recent fecal contamination from sources such as human sewage or
livestock waste
- indicate that there is a problem with your water supply
| Don’t
use water that has tested positive for Total coliform or E. coli. Don’t use
it for drinking, making infant formula and juices, cooking, making ice,
washing fruits or vegetables, brushing teeth, bathing or showering. And unless
you’ve disinfected it, don’t use it to wash hands. |
For more information, see the Ontario Ministry of Health and Long-Term Care Web
site. It’s listed at the end of this Information Sheet.
If your test results show the presence of indicator organisms, take action! Everyone
who drinks from your well is at risk. You must identify the source of contamination
and prevent its access to your well. It’s important to get the job done quickly
and right; consult a well contractor or your local health unit as soon as possible.
If your results show that your drinking water meets the Ontario Drinking Water
Standards, then continue to have the water tested at least three times a year. One
of the three samples you send for testing should be taken in the Spring.
| Sample
your well water until you have three consecutive samples (collected one to
three weeks apart) that meet the Ontario Drinking Water Standards of less than
5 Total coliform and no E. coli. |
To
the top
Changes in your water
It’s important to know the difference between water quality that could relate to
health concerns (termed health parameters) and those processes in nature that only
affect the appearance, smell or taste of your water (aesthetic parameters).
A change in your water’s aesthetic parameters is not necessarily a health risk.
However, they might signal contamination or deteriorating water quality. If you
notice a change in these parameters, you should submit a water quality sample for
testing as soon as possible.
If you are concerned about the potential presence of a particular contaminant, make
sure the contaminant is specifically tested for.
To learn more about what’s involved in having your well water tested, please see
the Information Sheet, Putting Your Well Water to the Test, in this series.
For more information about long-term water treatment options, please see the
Information Sheet, Choosing a Water Treatment System.
Test three times annually, and when…
In addition to regular testing, well water should be tested:
- after any repairs (such as pump repair or replacement)
- if the well has not been used for several weeks
- if there has been flooding, or
- there has been a change in water appearance, colour or odour.
And if you have one of the “highly vulnerable” water supplies described in Get
Acquainted with Your Well, you may want to consider having your well water
tested more frequently.
(Information adapted from Ministry of Ontario Information
Sheets)
To
the top
|
Leeds,
Grenville and Lanark District Health Unit -
Home Page 