rapid assessment of drinking-water quality in the republic of tajikistan

Faecal streptococci
Faecal streptococci may also be used as indicators of the microbiological quality of water. Compared
to E. coli, these bacteria have a stronger relationship to diarrhoeal disease and to bacterial indicators
of known human faecal origin. They are generally more environmentally resistant than E. coli or
thermotolerant coliforms and it has therefore been recommended that the levels of these bacteria be
tested in groundwater receiving contaminated recharge water and in chlorinated distribution systems.
A variety of techniques can be used for analysis and although some are simple, they are timeconsuming
and results cannot be obtained within 48 hours. This may limit their usefulness in routine
monitoring, but would have limited impact on their value in assessments.
The assessment results showed that 151 of 154 (98.1%) water samples tested for faecal streptococci
from utility piped supplies and protected springs met both the national standard and the WHO
guideline value (Table 3.4). For utility piped supplies, only 2 of 34 samples (5.9%) in Sughd did not
meet the requirements. Both came from the same supply scheme and also tested positive for
thermotolerant coliforms (the positive findings were not confirmed in the second sampling round, 3.5
months later). For springs, only one sample of 11 tested (9.1%) in RRS and Dushanbe was not in
compliance with the national standard, and again the sample had a high thermotolerant coliform count.
Table 3.4
Broad area a
Compliance with the Tajikistan national standard and WHO
guideline value for faecal streptococci
Utility piped supplies Protected springs Total
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
RRS & Dushanbe 49 100.0 11 90.9 60 98.3
Khatlon 35 100.0 11 100.0 46 100.0
Sughd 34 94.1 7 100.0 41 95.1
GBAO 2 100.0 5 100.0 7 100.0
a
National 120 98.3 34 97.1 154 98.1
GBAO = Gorno-Badakhshan Autonomous Oblast. RRS = rayons under direct republican subordination.
Table 3.5
Cumulative frequencies for faecal streptococci
Count category
(cfu/100 ml) a
Utility piped supplies Protected springs Total
Proportion
(%)
Cumulative
frequency
(%)
Proportion
(%)
Cumulative
frequency
(%)
Proportion
(%)
Cumulative
frequency
(%)
100 0.0 100.0 0.0 100.0 0.0 100.0
Total no. of samples 120 34 154
a
cfu = colony forming unit.
3.2 Chemical parameters
Many chemical substances that are found in water affect public health, the acceptability of the water
(aesthetics), and the operational performance of supplies. In the third edition of the WHO Guidelines
for drinking-water quality, for example, guidelines values are given for 98 such substances (WHO,
2004). However, it is expensive, difficult and largely unnecessary to test for all these parameters,
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