Water management is regulated by several acts implemented by different ministries.

Water management laws in Thailand:

  • Enhancement and Conservation of National Environmental Quality Act, B.E. 2535 (1992)
    The act is a fundamental environmental law in Thailand. Water pollution control is one of the focus of the act. It sets out environmental standard of surface water sources. Effluent standard from buildings or factories are prescribed.
  • Factory Act, B.E. 2535 (1992)
    The act regulates industrial premise as a stationary water pollution source. Industrial wastewater effluent released directly to the environment shall meet the standard under the act.
  • Water Resources Act, B.E. 2561 (2018)
    Flood and drought control is a critical issue in agrarian country. The act was enacted in 2018 for allocation, use, development, management, maintenance, rehabilitation and conservation of water resources.
  • Groundwater Act, B.E. 2520 (1977)
    Groundwater Act was enforced to control groundwater licensing, groundwater utilization and water infiltration to the wells in order to protect groundwater quantity and quality in Bangkok and its vicinities. In 1994, the act became enforced throughout Thailand.
  • Navigation in Thai Waters Act B.E. 2456 (1913)
    The act has been enforced to assure navigation of vessels. Some subsidiary notifications under the act specifies environmental requirements to prevent obstacles for navigation.
  • Industrial Estate Authority of Thailand Act, B.E.2522 (1979)
    The act sets effluent standard for factories in industrial estates to control pollution load incoming to central wastewater treatment plant of the industrial estates.


Industrial effluent standard

Different standard is applied for effluent released directly to the environment and effluent discharged to the central wastewater treatment plant in industrial estates. Parameters and standards are summarized as follows;

Industrial effluent standard in Thailand

No. Parameter Effluent released to environment Effluent from factory located in industrial estates
1 pH 5.5-9.0 5.5-9.0
2 Temperature 40℃ 45℃
3 Color 300 ADMI 600 ADMI
4 Odor not offensive
5 TDS:Total Dissolved Solids
(1) Release to water resource 3000mg/L 3000mg/L
(2) Release to water resource with high TDS (3000mg/L or higer) 3000mg/L  to 5000mg/L
6 Total Suspended Solids) 50mg/L 200 mg/L
7 BOD (Biochemical Oxygen Demand) 20 mg/L 500 mg/L
8 COD (Chemical Oxygen Demand) 120 mg/L 750 mg/L
9 Sulfide 1 mg/L 1 mg/L
10 Cyanides HCN 0.2 mg/L 0.2 mg/L
11 Fat oil and Grease 5 mg/L 10mg/L
12 Formaldehyde 1 mg/L 1 mg/L
13 Phenols 1 mg/L 1 mg/L
14 Free Chlorine 1 mg/L 1 mg/L
15 Pesticide Not detected Not detected
16 TKN (Total Kjeldahl Nitrogen) 100 mg/L 100 mg/L
17 Heavy metals
(1) Zn 5.0 mg/L 5.0 mg/L
(2) Hexavalent Chromium 0.25 mg/L 0.25 mg/L
(3) Trivalent Chromium 0.75 mg/L 0.75 mg/L
(4) As 0.25 mg/L 0.25 mg/L
(5) Cu 2.0 mg/L 2.0 mg/L
(6) Hg 0.005 mg/L 0.005 mg/L
(7) Cd 0.03 mg/L 0.03 mg/L
(8) Ba 1.0 mg/L 1.0 mg/L
(9) Se 0.02 mg/L 0.02 mg/L
(10) Pb 0.2 mg/L 0.2 mg/L
(11) Ni 1.0 mg/L 1.0 mg/L
(12) Mn 5.0 mg/L 5.0 mg/L
(13) Ag 1.0 mg/L
(14) Total Iron 10 mg/L
18 Fluoride 5 mg/L
19 Surfactants 30 mg/L

Apart from above-mentioned general effluent standard, industry-specific standard is applied for following sectors under Enhancement and Conservation of National Environmental Quality Act, B.E. 2535 (1992)

  • Leather
  • Pulp and paper
  • Seawater desalination plant

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