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

Table 3.9
Broad area
Compliance with the Tajikistan national standard and WHO
suggested value for iron a
Utility piped supplies Protected springs Total
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
RRS & Dushanbe 506 91.7 108 95.4 614 92.3
Khatlon 346 100.0 103 100.0 449 100.0
Sughd 410 80.7 60 81.7 470 80.9
GBAO 24 100.0 63 100.0 87 100.0
National 1 286 90.6 334 95.2 1 620 91.5
a
GBAO = Gorno-Badakhshan Autonomous Oblast. RRS = rayons under direct republican subordination.
Table 3.10 Compliance with WHO suggested value for turbidity a
Broad area
Utility piped supplies Protected springs Total
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
No. of
samples
Compliance
(%)
RRS & Dushanbe 506 73.5 108 98.1 614 77.9
Khatlon 346 95.7 103 100.0 449 96.7
Sughd 410 99.8 60 95.0 470 99.1
GBAO 24 100.0 63 100.0 87 100.0
National 1 286 88.3 334 98.5 1 620 90.4
a
GBAO = Gorno-Badakhshan Autonomous Oblast. RRS = rayons under direct republican subordination.
Compliance was generally higher for protected springs (98.5%) than for utility piped supplies (88.3%),
probably because spring water is generally more protected from matter causing turbidity. Indeed,
utility piped supplies in the broad area RRS and Dushanbe had the lowest compliance (73.5%), which
may be explained by the fact that most raw waters in this region are surface waters (i.e. rivers). In
autumn and spring, runoff caused by heavy rainfall and/or thaw pollutes the water sources with
particulate matter, causing turbidity, but the water-treatment works of piped supplies are inefficient at
removing turbidity. As the RADWQ survey was mainly conducted between the autumn of 2004 and
the spring of 2005, the results for RRS and Dushanbe most likely reflect this situation. In the other
broad areas, the level of compliance with turbidity standards was high because the raw waters for
utility piped supplies were often groundwaters such as artesian boreholes.
Conductivity
Conductivity, the ability of water to carry an electric charge, is a proxy indicator of dissolved solids
and is therefore an indicator of the taste/salinity of the water (a conductivity of 1400 µS/cm is
equivalent to 1000 µg/l total dissolved solids). Although there is little direct health risk associated
with this parameter, high values are associated with poor taste and hence customer dissatisfaction and
complaints. If conductivity changes over time, or if conductivity values are high, this can indicate
that the water is contaminated (e.g. from saline intrusion, faecal pollution or nitrate pollution) and can
cause corrosion in rising mains and pipes.
24