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by
Douglas Thomson
photography by Roger Yip |
CATCHING SOME RAYS |
| Ultraviolet
light zaps dangerous water contaminants |
In the last
few years there have been several serious contaminations of
residential water supplies in Canada. That said, most municipal
water treatment facilities take great care to ensure the water
they provide is safe. But what if you’re one of millions
of Canadians who rely on a well for water? Well water can become
contaminated quite easily. And the big fear—especially
since the Walkerton, Ont., and North Battleford Sask., contaminations—
is bacteria, particularily deadly strains of E. coli. One of
the newest methods to keep residential water bacteria-free are
high-intensity ultraviolet (UV) light filters that quickly kill
bacteria and viruses.
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| BEFORE
AND AFTER: the exisiting water treatment consisted
of a water softener only (above). The UV filter
system guards against potential bacterial contamination
(below). |
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|
Although
UV light filters have been used reliably in industrial applications
for many years they were bulky and expensive; recently, however,
smaller and less expensive systems became available for residential
use.
For this well water installation,
we started by having the water tested by a private lab. The
results were encouraging and the water was determined to be
completely safe to drink. The UV system was installed as a precaution,
in case of a bacterial contamination between regular tests.
We chose a UV unit made by Trojan
Technologies Inc., which meets stringent NSF International certification
requirements and enlisted the help of Trojan’s Reid Thornley
to oversee the entire installation.
The particular unit we chose monitors
the UV bulb’s intensity; an alarm sounds if the light intensity
decreases or the bulb fails. As an extra precaution we also
installed a solenoid valve which shuts off the water supply
in the event of a failure.
Acting on Reid’s recommedation,
we also installed a five-micron sediment filter upstream of
the UV unit. The sediment filter prevents floating particles
from reaching the UV chamber where they could potentially sheild
the bacteria from being exposed to the light.
| What
you'll need: |
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| PLUMBING:
propane torch, solid-core solder, paste flux, emery
cloth, pipe cutter, tape measure, adjustable wrenches
and pipe wrenches. Electrical: wire cutters and
strippers, assorted scredrivers, utility knife.
Other: drill, gloves and safety glasses. |
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The
final step to safeguard the water involves disinfecting all
the exisiting lines downstream from the UV filter with chlorine
bleach. Fill the sediment filter with bleach and open each water
outlet until the bleach is detected. Once the chlorine bleach
has filled the entire system, let it stand for four-to-six hours
before flushing with fresh water.
The complete system cost approximately
$700 (including the sediment filter and shut-off solenoid).
The installation took four hours.
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