INTERIM NATIONAL WATER QUALITY STANDARDS FOR MALAYSIA
WEPA Water Environment Partnership in Asia
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National Water Quality Standards For Malaysia
PARAMETER UNIT CLASS
I IIA/IIB III# IV V
Al mg/l - (0.06) 0.5
As mg/l 0.05 0.4 (0.05) 0.1
Ba mg/l 1 - -
Cd mg/l 0.01 0.01* (0.001) 0.01
Cr (IV) mg/l 0.05 1.4 (0.05) 0.1
Cr (III) mg/l - 2.5 -
Cu mg/l 0.02 - -
Hardness mg/l 250 - -
Ca mg/l - - -
Mg mg/l - - -
Na mg/l - - 3 SAR
K mg/l - - -
Fe mg/l 1 1 1 (Leaf) 5 (Others)
Pd mg/l 0.05 0.02* (0.01) 5
Mn mg/l 0.1 0.1 0.2
Hg mg/l 0.001 0.004 (0.0001) 0.002
Ni mg/l 0.05 0.9* 0.2
Se mg/l 0.01 0.25 (0.04) 0.02
Ag mg/l 0.05 0.0002 -
Sn mg/l - 0.004 -
U mg/l - - -
Zn mg/l 5 0.4* 2
B mg/l 1 (3.4) 0.8
Cl mg/l 200 - 80
Cl2 mg/l - (0.02) -
CN mg/l 0.02 0.06 (0.02) -
F mg/l 1.5 10 1
NO2 mg/l 0.4 0.4 (0.03) 1
NO3 mg/l 7 - 5
P mg/l 0.2 0.1 -
Silica mg/l 50 - -
SO4 mg/l 250 - -
S mg/l 0.05 (0.001) -
CO2 mg/l - - -
Gross-α Bg/l 0.01 - -
Gross-β Bg/l 1 - -
Ra-226 Bg/l < 0.1 - -
Sr-90 Bg/l < 1 - -
CCE µg/l 500 - -
MBAS/BAS µg/l 500 5000 (200) -
O&G (Mineral) µg/l 40 ; N N -
O&G (Emulsified Edible) µg/l 7000 ; N N -
PCB µg/l 0.1 6 (0.05) -
Phenol µg/l 10 - -
Aldrin/Dieldrin µg/l 0.02 0.2 (0.01) -
BHC µg/l 2 9 (0.1) -
Chlordane µg/l 0.08 2 (0.02) -
t-DDT µg/l 0.1 (1) -
Endoslufan µg/l 10 - -
Heptachlor/Epoxide µg/l 0.05 0.9 (0.06) -
Lindane µg/l 2 3 (0.4) -
2,4-D µg/l 70 450 -
2,4,5-T µg/l 10 160 -
2,4,5-TP µg/l 4 850 -
Paraquat µg/l 10 1800 -
Notes
* = At hardness 50 mg/l CaCO3
# = Maximum (unbracketed) and 24-hour average (bracketed) concentrations
N = Free from visible film sheen, discolouration and deposits 		Sourse : EQR2006

National Water Quality Standards For Malaysia
PARAMETER UNIT CLASS
I IIA IIB III IV V
Ammoniacal Nitrogen mg/l 0.1 0.3 0.3 0.9 2.7 > 2.7
Biochemical Oxygen Demand mg/l 1 3 3 6 12 > 12
Chemical Oxygen Demand mg/l 10 25 25 50 100 > 100
Dissolved Oxygen mg/l 7 5 - 7 5 - 7 3 - 5 < 3 < 1
pH - 6.5 - 8.5 6 - 9 6 - 9 5 - 9 5 - 9 -
Colour TCU 15 150 150 - - -
Electrical Conductivity* µS/cm 1000 1000 - - 6000 -
Floatables - N N N - - -
Odour - N N N - - -
Salinity % 0.5 1 - - 2 -
Taste - N N N - - -
Total Dissolved Solid mg/l 500 1000 - - 4000 -
Total Suspended Solid mg/l 25 50 50 150 300 300
Temperature °C - Normal + 2 °C - Normal + 2 °C - -
Turbidity NTU 5 50 50 - - -
Faecal Coliform** count/100 ml 10 100 400 5000 (20000)a 5000 (20000)a -
Total Coliform count/100 ml 100 5000 5000 50000 50000 > 50000
Notes
* = At hardness 50 mg/l CaCO3
# = Maximum (unbracketed) and 24-hour average (bracketed) concentrations
N = Free from visible film sheen, discolouration and deposits 		Sourse : EQR2006

DOE Water Quality Index Classification
PARAMETER UNIT CLASS
I II III IV V
Ammoniacal Nitrogen mg/l < 0.1 0.1 - 0.3 0.3 - 0.9 0.9 - 2.7 > 2.7
Biochemical Oxygen Demand mg/l < 1 1 - 3 3 - 6 6 - 12 > 12
Chemical Oxygen Demand mg/l < 10 10 - 25 25 - 50 50 - 100 > 100
Dissolved Oxygen mg/l > 7 5 - 7 3 - 5 1 - 3 < 1
pH - > 7 6 - 7 5 - 6 < 5 > 5
Total Suspenbed Solid mg/l < 25 25 - 50 50 - 150 150 - 300 > 300
Water Quality Index (WQI) - < 92.7 76.5 - 92.7 51.9 - 76.5 31.0 - 51.9 > 31.0

Water Classes And Uses
CLASS USES
Class I Conservation of natural environment.
Water Supply I - Practically no treatment necessary.
Fishery I - Very sensitive aquatic species.
Class IIA Water Supply II - Conventional treatment.
Fishery II - Sensitive aquatic species.
Class IIB Recreational use body contact.
Class III Water Supply III - Extensive treatment required.
Fishery III - Common,of economic value and tolerant species;livestock drinking.
Class IV Irrigation
Class V None of the above.
Sourse : EQR2006

DOE Water Quality Classification Based On Water Quality Index
SUB INDEX &
WATER QUALITY INDEX		 INDEX RANGE
CLEAN SLIGHTLY POLLUTED POLLUTED
Biochemical Oxygen Demand(BOD) 91 - 100 80 - 90 0 - 79
Ammoniacal Nitrogen(NH3-N) 92 - 100 71 - 91 0 - 70
Suspended Solids(SS) 76 - 100 70 - 75 0 - 69
Water Quality Index(WQI) 81 - 100 60 - 80 0 - 59
Sourse : EQR2006


WQI FORMJLAAND CALCULATION

FORMULA

WQI = (0.22* SlDO) + (0.19*SIBOD) + (0.16*SICOD) + (0.15*SIAN) + (0.16 * SISS) + (0.12 * SipH)
where;
SIDO = Sublndex DO (% saturtlon)
SIBOD = Sublndex BOD
SICOD = Sublndex COD
SIAN = Sublndex NH3-N
SISS = Sublndex SS
SipH = Sublndex pH
0 ≤ WQI ≤ 100


BEST FIT EQUATIONS FOR THE ESTIMATION OF VARIOUS SUBINDEX VALIES

Sublndex for DO (In % saturatlon)  
SIDO = 0 for x ≤8
SIDO = 100 for x ≤92
SIDO = -0.395 + 0.030x2 - 0.00020x3 for 8 < x < 92
 
Sublndex for BOD  
SIDOD = 100.4 - 4.23x for x ≤ 5
SIDOD = 108* exp(-0.055x) - 0.1x for x > 5
 
Sublndex for COD  
SICOD = -1.33x + 99.1 for x ≤ 20
SICOD = 103* exp(-0.0157x) - 0.04x for x > 20
 
Sublndex for NH3-N  
SIAN = 100.5 - 105x for x ≤ 0.3
SIAN = 94* exp(-0.573x) - 5* I x - 2 I for 0.3 < x < 4
SIAN = 0 for x ≥ 4
 
Sublndex for SS  
SISS = 97.5* exp(-0.00676x) + 0.05x for x ≤ 100
SISS = 71* exp(-0.0061x) + 0.015x for 100 < x < 1000
SISS = 0 for x ≥ 1000
 
Sublndex for pH  
SlpH = 17.02 - 17.2x + 5.02x2 for x < 5.5
SlpH = -242 + 95.5x - 6.67x2 for 5.5 ≤ x < 7
SlpH = -181 + 82.4x - 6.05x2 for 7 ≤ x < 8.75
SlpH = 536 - 77.0x + 2.76x2 for x ≥ 8.75
 
Note:
*means multlply wlth		  



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