Local Council Water Treatment
Understanding Local Council Water Treatment
Local Council Water Treatment removes many water contaminants
but is it really sufficient to prevent outbreaks of
water borne illness. Those contaminants commonly found
in treated water include:
- Bacteria - bacterium E. coli,
which is found in animal gut is not harmful itself,
rather it indicates the potential presence of other
more dangerous organisms such as Cholera and Typhoid.
- Protozoan cysts – such as
Giardia and cryptosporidium protozoa live in the intestines
of humans and animals. Their cysts are passed out
in faeces. If they get into the water source they
can cause severe diarrhoea or worse. Cryptosporidiosis
may be fatal in people with lowered immunity. These
organisms exist in the water in clumps and may settle
to the bottom in still water, to reappear in the water
flow when disturbed, perhaps by heavy rain in the
catchment area. This makes them very hard to detect
in normal testing. The cysts are not killed by Chlorination
or most UV light treatment systems. Chemical coagulation
causes particles, including giardia and cryptosporidium
cysts, to form a sludge which can be filtered out.
Despite these measures, giardia and cryptosporidium
do contaminate water supplies. Local water supplies
are required to issue a "boil water" warning
if there is a risk of your drinking water becoming
contaminated.
- Chemicals - Traces of treatment
plant chemicals added to the water to kill or help
remove bugs, or to improve its look, smell or taste,
may remain in the water, some with possible harmful
side-effects. Authorities must monitor the levels
of these chemicals to ensure they remain within World
Health Organisation (WHO) guidelines.
- THMs - Chlorine can react with
organic matter such as decayed vegetation in water
to form potentially harmful by-products called trihalomethanes
(THMs). The most common THM is chloroform. Some studies
have suggested a possible link between chlorinated
tap water and a slightly higher risk of some forms
of cancer.
- Aluminium - aluminium occurs naturally
in river and lake water and is often used in chemical
coagulation to remove suspended particles from water,
making it clearer. While most of the aluminium can
be filtered out of water, small amounts may pass through.
- Fluoride - fluoride added to water
has a proven record of reducing tooth decay. Negatively
charged ion exchange resins will remove fluoride.
- Heavy Metals - such as lead, nickel,
cadmium, mercury, arsenic, etc occur due to corrosion
of copper pipe fittings by acidic or 'aggressive'
water. Other metals can be leached or washed into
water supplies from industrial activities, although
this is rare in well managed areas
- Natural contaminants - Some chemical
contaminants occur naturally; heavy metals in some
areas, or nitrates in farming districts.
- THM 's ( Trihalomethanes ) - are
a range of toxic chloroform chemicals and are a by-product
of the reaction between chlorine and organic material
in water. NZ research has shown that 25% of all rectal,
bowel and bladder cancers and 25% of all birth defects
in NZ can be attributed to these by-products of chlorination.
Not all purifiers are effective at removing these
chemicals, and most will only remove them for a short
time. A high capacity carbon block cartridge or Reverse
Osmosis are generally most effective at removing THM
's.
Untreated Water Supply
People in rural areas, or with private supplies, may
face problems of contamination by agricultural runoff,
pesticides and herbicides. Systems which collect water
from the roof are vulnerable to contamination by birds
and animals. Bore water, particularly shallow bore water,
may contain nitrates, pesticides and harmful bacteria.
In summary, you can see that there are a number of
factors that may not provide you will consistent water
quality at your kitchen faucet. To overcome any health
risk it is recommended that you further treat, treated
water using home purification systems.
Three main purification systems exist:
- Activated
Carbon Filters
- Reverse
Osmosis Systems
- Water
Distillers
Next: More
Resources on Water Quality and Water Filters
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