The groundwater quality assessment is based on the water quality data obtained
in this survey. It encompasses the indicator-specific evaluation and comprehensive
evaluation. Five grades are defined for indicator-specific evaluation according to the
indicators for groundwater quality classification (Table 5.42). For comprehensive
evaluation, the results depend on the lowest grade in identified in the
indicator-specific evaluation, and clarify the lowest-grade indicators.
Table 5.42 Indicators for groundwater quality classification
Grade I
Grade II
Grade
III
Grade IV
Grade V
Flavor level
No
No
No
No
Yes
Turbidity (degrees)
3
3
3
10
>10
Macroscopic objects
No
No
No
No
Yes
pH
6.5
pH
8.5
5.5
pH < 6.5
8.5 < pH
9
pH<5.5 or
pH>9.0
Total hardness (mg/L)
150
300
450
650
>650
Salinity (mg/L)
300
500
1000
2000
>2000
Sulfate (mg/L)
50
150
250
350
>350
Chloride (mg/L)
50
150
250
350
>350
Iron (mg/L)
0.1
0.2
0.3
2.0
>2.0
Manganese (mg/L)
0.05
0.05
0.10
1.50
>1.50
Copper (mg/L)
0.01
0.05
1.0
1.50
>1.50
Zinc (mg/L)
0.05
0.5
1.0
5.0
>5.0
Aluminum (mg/L)
0.01
0.05
0.20
0.50
>0.50
Volatile phenols
0.001
0.001
0.002
0.01
>0.01
Nitrate (mg/L)
2.0
5.0
20
30
>30
Nitrite (mg/L)
0.01
0.10
1.00
4.80
>4.80
Fluoride (mg/L)
1.0
1.0
1.0
2.0
>2.0
Iodide (mg/L)
0.04
0.04
0.08
0.50
>0.50
Cyanide (mg/L)
0.001
0.01
0.05
0.1
>0.1
Arsenic (mg/L)
0.001
0.001
0.01
0.05
>0.05
Lead (mg/L)
0.005
0.005
0.01
0.10
>0.10
Ammonia nitrogen
(mg/L)
0.02
0.1
0.5
1.5
>1.5
Mercury (mg/L)
0.0001
0.0001
0.001
0.002
>0.002
Chromium (hexavalent)
(mg/L)
0.005
0.01
0.05
0.1
>0.1
Gross alpha
radioactivity (Bq/L)
0.1
0.1
0.5
>0.5
>0.5
Gross beta radioactivity
(Bq/L)
0.1
1.0
1.0
>1.0
>1.0
Total coliforms (/L)
3.0
3.0
3.0
100
>100
Total bacteria (/L)
100
100
100
1000
>1000
5.2 Northwest China
177