Why You Need A Water Test Kit For Your
Family's Health
| Bacteria and impurities in water is a major cause for
concern in many households. It shows up everywhere. It is on the food
we eat and in the water coming from our tap. We are exposed to it
everyday when out in public. Coughs and sneezes carry it. It can even
be found on hard surfaces. |
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Everyone should think about a water test kit for their
home. No matter where you live. Because you never know until you do the
testing. Let's take a look at what can be waterborne in what you and your
family drink.
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The health problems associated with waterborne
Cryptosporidium and Giardia lamblia are well known. Up to 400,000 people
were affected in the largest recorded outbreak of Cryptosporidium, in
Milwaukee in the USA. As well as being a major dilemma for water
companies, these protozoan parasites are also a problem for
environmental health officers.
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There are risks of Cryptosporidium associated with
private source supplies that do not apply to municipal sources. These
are: the immediate proximity of young farm animals to many supplies;
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the inadequate protection of many sources leading to
rainwater washing faecal material into the collection point; and
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the absence of treatment to many supplies and the
inadequacy of the treatment systems that are installed.
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The Private Water Supplies Regulations 1991 (HMSO, 1991)
do not require private sources such as wells to be monitored for
Cryptosporidium or Giardia lamblia. They rely on the presence of a
single faecal indicator organism (faecal coliforms) to alert local
authorities to the possible contamination by pathogens. Because of its
longevity Cryptosporidium may be isolated in water where the coliform
population has become inactive.
Because of these theoretical risk factors, Bradford and
District Metropolitan Council successfully applied to the Department of
the Environment for research funding to investigate the problem. During
the winter period of 1996/7 with Craven District Council we regularly
tested 15 high-risk supplies to find out the extent of the problem. We
selected as wide a variety of supplies as possible within that risk
category. All the sites were spring and surface water supplies rather than
boreholes. They included commercial and domestic supplies and the
population using the water ranged from one house to a whole village.
Rainfall Effects
Previous studies of environmental water samples have often indicated an
association between rainfall and Cryptosporidium. There has been found to
be an increase of cases in the early spring with a second lessor peak in
the mid autumn period. It has been proposed that these peaks coincide with
high rainfall. This is also the time of farming events such as slurry and
muck spreading, lambing and calving. There appears to be a corresponding
association with general contamination of private water supplies at these
times.
The connection between rainfall and contamination is
relevant because monitoring should take place at the time when conditions
are most likely to produce the poorest results. We therefore sampled just
after significant precipitation events when, should contamination occur,
we would have a reasonable chance of finding it. Sampling therefore
normally followed times of rain. The only samples that were not taken
within two days of rain were those following periods of snow. The sampling
then took place the day after a thaw.
Methodology
Fifteen sites were selected and sampled ten times each. The aim of the
study was to select supplies that were worst cases and to sample them when
they were most likely to be contaminated. In that way if Cryptosporidium
and Giardia lamblia were going to be found in private water supplies our
methodology should find them.
Supplies were rated on a number of points, including:
type of supply, ie. spring or surface supply,
source protection,
quantity of animals on or up hill from the site, condition of collection
chambers, tanks and pipework, and
previous results for faecal coliforms.
The sampling was carried out according to the procedures laid down in
Report 71, 'The Microbiology of Water 1994, Part 1 - Drinking Water'. [7]
All sampling took place early in the morning and samplers were required to
visit at approximately the same time for each site. This was to remove the
effect of any possible diurnal variations in contamination load.
Results
During the sampling period nine of the 15 supplies were found to contain
Cryptosporidium (60 per cent). In addition, eight of the supplies also
contained Giardia lamblia (53.3 per cent). Cryptosporidium was found in 21
(14 per cent) of the 150 samples taken. This ranged from nil positive
results in some of the supplies to 40 per cent of the samples in the most
highly contaminated. Twelve positive results for Giardia lamblia cysts
were found in the samples (8 per cent). Of the 21 positive results for
Cryptosporidium, 57.1 per cent were also positive for Giardia lamblia
We also looked at other parameters of water quality to try
and establish a link between them and Cryptosporidium. Statistically
significant correlations to Cryptosporidium for Faecal streptococci (r =
0.6783 p 0.001) and Clostridium perfringens (r = 0.6268 p 0.001) were
found.
There was no significant correlation in this study between
Cryptosporidium and coliforms (either total or faecal), turbidity,
conductivity or the sanitary assessment score.
The use of a combination of indicators may identify
potential problems. Multiple regression analysis with turbidity, faecal
and total coliforms, Faecal streptococci and Clostridium perfringens gave
an R2 value of 0.6259. This shows that 62.6 per cent of the variation in
Cryptosporidium levels could be accounted for by these factors. It should
be emphasised that this is not a causal relationship. The benefits,
however, of including Faecal streptococci and Clostridium perfringens in
sampling programs are clear.
From an article posted on http://www.cieh.org/research/crypto/article.htm
Chartered Institute of Environmental Health.
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