Drinking Water Quality Standard in Thailand
WEPA Water Environment Partnership in Asia
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Drinking Water Quality Standard in Thailand

Properties Parameter Units Standards
Maximum Acceptable Concentration Maximum Allowable Concentration
Physical 1. Colour Platinum-Cobalt
(Pt-Co)
5 15
2. Taste Non Objectionable Non Objectionable
3. Odour Non Objectionable Non Objectionable
4. Turbidity Silica scale unit (SSU) 5 20
5. pH 6.5 - 8.5 9.2
Chemical 6. Total Solids mg/dm³ 500 1,500
7. Iron (Fe) mg/dm³ 0.5 1.0
8. Manganese (Mn) mg/dm³ 0.3 0.5
9. Iron & Manganese (Fe&Mn) mg/dm³ 0.5 1.0
10. Copper (cu) mg/dm³ 1.0 1.5
11. Zinc (Zn) mg/dm³ 5.0 15.0
12. Calcium (Ca) mg/dm³ 75b 200
13. Magnesium (Mg) mg/dm³ 50 150
14. Sulphate (SO4) mg/dm³ 200 250c
15. Chloride (Cl) mg/dm³ 250 600
16. Fluroride (F) mg/dm³ 0.7 1.0
17. Nitrate (NO3) mg/dm³ 45 45
18. Alkylbenzyl Sulfonates (ABS) mg/dm³ 0.5 1.0
19. Phenolic substance (as phenol) mg/dm³ 0.001 0.002
Toxic elements 20. Mercury (Hg) mg/dm³ 0.001
21. Lead (Pb) mg/dm³ 0.05
22. Arsenic (As) mg/dm³ 0.05
23. Selenium (Se) mg/dm³ 0.01
24. Chromium (Cr hexavalent) mg/dm³ 0.05
25. Cyanide (CN) mg/dm³ 0.2
26. Cadmium (Cd) mg/dm³ 0.01
27. Barium (Ba) mg/dm³ 1.0
Bacterial 28. Standard plate count Colonies/cm³ 500
29. Total coliform MPN/100cm³ < 2.2
30. E.coli MPN/100cm³ None
Remarks: mg/dm³ = milligram per cubic decimeter
  MPN = Most Probable Number
  a = These values are allowed for tap water or ground water that is used as temporary drinking water. Such water with a parameter between the maximum acceptable concentration and the maximum allowable concentration can not be certified as standard drinking water for industrial products and stamped with the standard logo.
  b = If the calcium concentration is higher than the standard and magnesium concentration is lower than the standard, calcium and magnesium will be identified in terms of total hardness with a standard value of less than 300 mg/dm³ (as CaCO3)
  c = If a sulphate concentration of 250 mg/dm³ is reached, magnesium concentration must not be more than 30 mg/dm³.

Source : Notification of the Ministry of Industry, No. 322, B.E. 2521 (1978), issued under the Industrial Products Standards Act B.E. 2511 (1968), published in the Royal Gazette, Vol. 95, Part 68, dated July 4, B.E. 2521 (1978).

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