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In general, water from the artesian wells has
obviously a better quality (less organics, chlororganics and
nitrates) than
water
from the tap or compared to
water
from shallow village wells.
That
water is rather warm (12 -15 oC), even in winter.
The redox potentials (oxidation state) vary distinctly and sometimes
a bad smell similar to rotten eggs (H2S)
can be detected. This type of smell usually has natural
reasons and lasts only a few minutes. Other natural compounds
can also occur in high concentrations above drinking water limits;
information was published by the Institute of Colloid and Water
Chemistry in Kiev.
Fortunately,
nitrate concentrations (NO3-N
in the figure below) are usually low, the same is true for the
organic load of this water (controlled by measurements of
SAC254
in 1/m). But exceptions are possible (see figure) - at least
for some time. The reason for this is not always known.
The
wells are officially controlled, but nevertheless, pollution
already occurs and is not always detected. In a few cases,
we have detected chlororganic compounds (up to 300 microgram
AOX per litre - see figure!). As long as they have not yet been
identified, one has to take into account that they are dangerous
or even very dangerous for human health. More details --->
read
articles!
To get an official statement about the possible occurrence of
those compounds, you should ask the city water authorities,
Vodocanal and
"SanEpidemStanzije", (SES).
Latest measurements in June 2000 showed that the problem still
exists, the concentrations of chlororganics were however smaller
than in former years.
The contamination of these water
resources, because of more and more holes having been drilled
into the underground (and possibly because of sewer leakage),
is not acceptable at all and would have been possible
to avoid or at least to be minimised. The water authorities
should recognise their responsibility for this fact.
The official controls should include chlororganic and other
toxic organic compounds and not only harmless substances like
sulphate, carbonate etc. the concentration of which is indicated
on tables above the well. This could perhaps help to regain the trust
of the consumers.
Nevertheless, problems of tap water quality have to be solved
in the water work (rather than drilling more and more holes)!!!
Additional information for water experts:
EC = electr. conductivity given in mS/m;
NO3-N (nitrate) is given as nitrogen in mg/L, but concentrations
are usually < 1 mg/L;
SAC_254 (in 1/m) is the spectral absorption coefficient at 254
nm per meter; this measurement allows to estimate the organic
load: if results > 10 1/m are detected, the type of load
should be clarified.
AOX:
adsorbable organic halogens in microgram/L Cl.
The plot shows the medium, 25% and 75% percentile and min./max.
values
Analytical information
sources are given in the
overview
of methods
