Drinking Water Quality Status and Contamination in Pakistan
Table 1
National Standards for Drinking Water Quality.
Parameters
Standard values for Pakistan
WHO standards
Biological
All water intended for drinking (E. coli or thermotolerant coliform bacteria)
Must not be detectable in any 100 mL sample
Must not be detectable in any 100 mL sample
Treated water entering the distribution system (E. coli or thermotolerant coliform and total coliform bacteria)
Must not be detectable in any 100 mL sample
Must not be detectable in any 100 mL sample
Treated water in the distribution system (E. coli or thermotolerant coliform and total coliform bacteria)
Must not be detectable in any 100 mL sample In case of large supplies, where sufficient samples are examined, it must not be present in 95% of the samples taken throughout any 12-month period
Must not be detectable in any 100 mL sample In case of large supplies, where sufficient samples are examined, it must not be present in 95% of the samples taken throughout any 12-month period
Physical
Color
≤15 TCU
≤15 TCU
Taste
None
None
Odor
None
None
Turbidity
<5 NTU
<5 NTU
Total hardness as CaCO3
<500 mg/L
—
TDS
<1000
<1000
pH
6.5–8.5
6.5–8.5
Chemical
Essential inorganic
mg/L
mg/L
Aluminum (Al) mg/L
≤0.2
0.2
Antimony (Sb)
≤0.005 (P)
0.02
Arsenic (As)
≤0.05 (P)
0.01
Barium (Ba)
0.7
0.7
Boron (B)
0.3
0.3
Cadmium (Cd)
0.01
0.003
Chloride (Cl)
<250
250
Chromium (Cr)
≤0.05
0.05
Copper (Cu)
2
2
Toxic inorganic
mg/L
mg/L
Cyanide (CN)
≤0.05
0.07
Fluoride (F)
≤1.5
1.5
Lead (Pb)
≤0.05
0.01
Manganese (Mn)
≤0.5
0.5
Mercury (Hg)
≤0.001
0.001
Nickel (Ni)
≤0.02
0.02
Nitrate (NO3)
≤50
50
Nitrite (NO2)
≤3 (P)
3
Selenium (Se)
0.01 (P)
0.01
Residual chlorine
0.2–0.5 at consumer end, 0.5–1.5 at source
—
Zinc (Zn)
5.0
3
Organic
Phenolic compounds (phenols) mg/L
≤0.002
Polyaromatic hydrocarbons (PAH) g/L
0.01 (by GC/MS method)
indicates priority health related inorganic constituents which need regular monitoring.
