| Choosing
a Water Treatment System
•
Private
Well Water Technologies
•
Common
Well Water Quality Problems
While there are many
technologies out there, each one is effective for a specific water contamination
concern. No single treatment technology works for all. So, when you’re selecting
and applying a water treatment system, use great care to make sure it is the right
one for your particular situation. Let’s examine some circumstances that can make
treatment necessary.
Treatment alone may not be enough to guarantee a consistent supply of safe and high
quality water. In some cases, such as below-grade wells, structural changes may need
to be made to maintain good water quality.
Why treat your water supply?
You may have to treat your well water to make it safe to drink if you draw your
water supply from: water that is “highly vulnerable” to contamination –
described in Get Acquainted with Your Well; a
poorly constructed well or one that cannot be repaired to meet today’s well
construction standards; or a source that has periodic episodes of poor water
quality. If any of these situations applies to you, your drinking water may be
susceptible to harmful organisms (pathogens such as bacteria, parasites and
viruses), chemicals and other changes to your water’s taste, odour and/or
appearance.
As you’re learning more about treatment systems, just a reminder: begin with a
properly built and maintained well, and have your water tested regularly. Otherwise,
you may always be treating a problem, and never resolving it.
Ask around
It’s always in your best interest to find out as much as possible about your
well. The local public health unit, the Ontario Ministry of the Environment (MOE),
your Water Well Record available from MOE, water well drillers, municipal staff,
environmental consultants and neighbours may all have useful information. As a well
owner, you need to review all this information carefully to help you decide if
testing your well water for dissolved chemicals is needed.
Choosing a
treatment system
Treating highly vulnerable sources can be costly and tricky
Treatment systems can be used on water from most sources in order to make it safe
for drinking. However, treating highly vulnerable water sources is usually expensive
and difficult, and will require a great deal of your time to make sure the equipment
is looked after properly. Contact us and/or a water treatment professional when
selecting, installing and operating a treatment system.
By contrast, treating water from properly constructed and maintained wells is
generally easier, but again the technology used must be selected carefully.
Remember their limitations!
Here are a few key limitations of treatment systems.
- Disinfecting a
well with chlorine works against bacteria and many viruses, but cannot be relied
on to kill all parasites. Also, chlorine cannot be relied on to kill tiny
organisms embedded inside tiny dirt particles. For water sources that may be
contaminated with surface water, an effective filtration treatment will also be
needed.
- There are many
treatment systems on the market. Some of these are referred to as “point-of-use”
systems, where the equipment is attached to one faucet. Others are “in-line”
and provide treated water for an entire home. These systems are based on
different technologies, ranging from chemical treatment to mechanical treatment
(e.g., filters to ultra-violet light). Each system has its benefits and
limitations.
- Heating water to a
rolling boil for at least one minute is an effective method for killing harmful
organisms. However, it does not remove most dissolved contaminants (such as
chemicals) and it is impractical for treating large quantities of water.
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Don’t scrimp on
installation
For each water treatment system to remain effective, it must be installed, operated
and maintained as directed by the manufacturer. In water treatment, there are no
shortcuts!
|
Private
Well Water Technologies |
| Method |
Uses |
Limitations |
Comments |
| Distillation |
•
kills all microbes by heat • removes heavy metals and nitrates •
often used in combination with activated carbon filters |
•
can remove only chemicals (e.g., fluoride, iron, nitrate) with a higher
boiling point than water |
•
needs regular de-scaling and weekly disinfecting with bleach or heat • can
concentrate chemicals (with boiling points lower than water) in distilled
water (e.g., ammonia) |
| Ultra-Violet |
•
kills bacteria and viruses |
•
needs filtration to remove microbes embedded in dirt particles, including
parasites |
•
needs very fine (5 micron pre-filter), slow water flow, and UV lamp must be
kept clean |
| Chlorination |
•
kills bacteria and viruses • can be used to remove some forms of iron, as
long as water is filtered after chlorination |
•
needs filtration to remove microbes shielded or embedded in dirt particles,
including parasites |
•
needs careful handling of chlorine, testing of chlorine levels, and
maintenance of dosing pump |
| Ozonation |
•
kills most microbes, but not cryptosporidium • removes organic compounds,
including pesticides • can be used in combination with activated carbon
filters |
needs
filtration to remove microbes embedded in dirt particles, including parasites |
•
varies in effectiveness depending on application and manufacturer • contact
local public health unit for more information |
| Activated
Carbon Contactors |
•
remove small amounts of some chemicals • used for removing tastes and odours,
and reducing trace levels of organic chemicals (e.g., pesticides) |
•
are not suitable for removing minerals, or larger amounts of chemicals |
•
must be replaced regularly but hard to know when contactors are exhausted •
can become a dangerous source of bacteria and taste and odour problems |
| Filters |
•
use ceramic candle filters to remove bacteria and parasites, but not viruses
• use other filter types to remove sand, sediment, rust and particles •
use specially rated filters to remove very small particles |
•
need chlorination in addition to ceramic candle filters to remove viruses |
•
need regular maintenance and replacement for proper operation |
| Greensand
Treatment |
•
removes moderate amounts of iron and manganese |
•
is unsuitable for removing microbes |
•
is not easy to operate or maintain • needs regular backwash and periodic
reactivation with permanganate solution and/or bleach |
| Reverse
Osmosis |
removes
nitrates, sulphate, hardness, most microbes, dirt particles and small amounts
of some pesticides |
•
can result in plugged membranes due to hard water |
•
is costly because of need to replace membrane • needs prefiltration and
softening of hard water |
| Softeners |
•
reduce hardness that produces lime deposits on dish-washed items, and gives a
starched effect on laundry |
•
are not suitable for removing microbes or most chemicals • increase sodium
concentration in treated water |
•
need periodic replacement of softener salt and disposal of concentrated salty
water |
Please note:
Equipment carrying the National Standards Foundation (“NSF certified”) trademark
has been thoroughly checked for performance and the manufacturing facility is
inspected annually. There are several NSF standards. Check for the appropriate NSF
standard number for your treatment
needs. Consult your local public health unit and reputable expert companies.
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| Common
Well Water Quality Problems |
| Concern |
Cause |
Consequences |
Options |
| E.
Coli Bacteria Detected |
•
human or animal sewage getting into well |
•
may result in serious illness –of special concern to visitors, infants,
seniors and other frail individuals • stop using well water |
•
use alternate water supply, and • consult local public health unit staff for
advice |
| Coliform
Bacteria (Total Coliform > 5 Counts) |
•
surface water getting into well |
•
early warning of possible illness |
•
consult local public health unit for advice • inspect and repair well •
shock chlorinate well if necessary, and • retest |
| Fluoride |
•
naturally occurring mineral in aquifer |
•
high levels can result in mottling of children’s teeth • in severe cases,
bone defects can occur |
•
test for level • avoid fluoride dental treatment and toothpaste, and •
distill water for drinking or use bottled water if level is very high |
| Iron |
•
naturally occurring mineral in aquifer |
•
yellow or red cloudy water • not hazardous to health • can stain plumbing
and laundry • may increase over time and make well water unusable |
•
use chlorination–filtration • consider greensand treatment, and •
distill water |
| Iron
Bacteria |
•
growth of non-harmful bacteria, creating black slime and particles |
•
well pump failure (overheating), low flow rates • may increase over time |
•
shock chlorinate |
| Pesticides |
local
spraying, spills |
•
long-term health risk |
•
stop using well water• use alternate water supply, and • consult local
Ministry of the Environment and public health unit staff about treatment
options |
| Fuels
(Gasoline, Diesel, Heating Oil) |
•
leaking old storage tank, spills |
•
long-term health risk |
•
stop using well water• use alternate water supply, and • consult local
Ontario Ministry of the Environment and public health unit staff about
treatment options |
| Nitrates |
•
nutrient application and septic systems |
•
health risk for infants when nitrate is above 10 ppm |
•
use alternative water supply for drinking and cooking, and • use reverse
osmosis or distillation |
| Hydrogen
Sulphide |
•
naturally occurring gas, or harmful bacteria that is releasing sulphate |
•
not a health hazard |
•
use chlorination–filtration, and • use greensand treatment |
| Hardness |
•
naturally occurring minerals in aquifer |
•
not a health hazard |
•
add softener, and • use an alternate soap and detergent for moderately hard
water |
Please note:
- Deep well water
quality is not constant and can change over time. Iron and manganese
concentrations may increase to unacceptable or untreatable levels. Iron bacteria
problems can also become severe enough to force well abandonment.
- Shallow well water
quality can change seasonally. Water quality in highly vulnerable wells (less
than 3 metres or 10 feet in depth) may change within hours or several days after
rainstorms or thaws.
(Information
adapted from Ministry of Ontario Information
Sheets)
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|
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Grenville and Lanark District Health Unit -
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