Lake Water Testing Service

Item

Limit

Chemical Indicators

Turbidity

Not exceeding 1 NTU①, and not exceeding 5 NTU under special circumstances

pH

6.5–8.5

Total Hardness (as CaCO₃)

450 (mg/L)

Aluminum

0.2 (mg/L)

Iron

0.3 (mg/L)

Manganese

0.1 (mg/L)

Copper

1.0 (mg/L)

Zinc

1.0 (mg/L)

Volatile Phenols (as phenol)

0.002 (mg/L)

Anionic Synthetic Detergents

0.3 (mg/L)

Sulfates

250 (mg/L)

Chlorides

250 (mg/L)

Total Dissolved Solids

1000 (mg/L)

Oxygen Consumption (as O₂)

3 (mg/L), not exceeding 5 mg/L under special circumstances②

Toxicological Indicators

Arsenic

0.05 (mg/L)

Cadmium

0.005 (mg/L)

Chromium (Hexavalent)

0.05 (mg/L)

/

0.05 (mg/L)

Fluorides

1.0 (mg/L)

Lead

0.01 (mg/L)

Mercury

0.001 (mg/L)

Nitrates (as N)

20 (mg/L)

Selenium

0.01 (mg/L)

Tetrachloroethylene

0.002 (mg/L)

Chloroform

0.06 (mg/L)

Bacteriological Indicators

Total Bacterial Count

100 (CFU/mL)③

Total Coliforms

Not detectable in 100 mL water sample

Fecal Coliforms

Not detectable in 100 mL water sample

Free Residual Chlorine

Should be no less than 0.3 mg/L after 30 minutes of contact with water, and no less than 0.05 mg/L at the end of the pipe network (applicable for chlorination disinfection)

Radioactive Indicators④

Total α Radioactivity

0.5 (Bq/L)

Total β Radioactivity

1 (Bq/L)

Note: ① NTU in the table stands for Nephelometric Turbidity Unit.

② Special circumstances include source water limitations, etc.

③ CFU stands for Colony Forming Unit.

④ The values for radioactive indicators are not limits but reference levels. When radioactive indicators exceed the values specified in Table 2-1, nuclide analysis and evaluation must be conducted to determine whether the water is drinkable.