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Taipei Water Department

International Comparison of Water Quality

Comparison of TWD's Tap Water Quality with U.S., Japan, E.U., W.H.O.'s Guidelines, and Water Quality Standards of EPA, R.O.C.

 

Microbial Parameters

Parameters TWD
Tap Water
Quality
Maximum Contaminant Level
Taiwan
(2017)
U.S.
(2012)
Japan
(2015)
E.U.
(2015)
W.H.O.
(2011)
1.Total Coliforms
(CFU/100ml,MPN/100ml)
<1 6 5.0%
1*2
0*3 0 0
2.Total Bacterial
Count

(CFU/ml)
<1 100 - 100 *4
(22˚C)
0
Unit : mg/L (unless specified otherwise)
Maximum Contaminant Level Goal(MCLG):The level of a contaminant in drinking water below which there is no known or expected risk to health. MCLGs allow for a margin of safety and are non-enforceable public health goals.
*1.No more than 5.0% samples total coliform-positive in a month. (For water systems that collect fewer than 40 routine samples per month, no more than one sample can be total coliform-positive per month.)
*2. Fecal coliform and E. coli are bacteria whose presence indicates that the water may be contaminated with human or animals wastes.
*3. Drinking water standard of Japan set E-coli only.
*4. Acceptable to consumers and no abnormal change.  

Physical Parameters

Parameters
TWD
Tap Water
Quality
Maximum Contaminant Level
Taiwan
(2017)
U.S.
(2012)
Japan
(2015)
E.U.
(2015)
W.H.O.
(2011)
1.Odor (TON)
1 3 35 *4 *4 *4
2.Turbidity (NTU)
0.18 2 TT6 2 *4 1.5
3.Color (Pt-Co units)
2 5 155 5 *4

5

Unit : mg/L (unless specified otherwise)
NTU = nephelometric turbidity unit.
*5. National Secondary Drinking Water Regulations (NSDWRs or secondary standards)
*6. TT :Treatment technique required
 

Chemical Parameters

Parameters TWD
Tap Water
Quality
Maximum Contaminant Level
Taiwan
(2017)
U.S.
(2012)
Japan
(2015)
E.U.
(2015)
W.H.O.
(2011)

(A) Substances affecting health

1. Arsenic (As)
ND
(< 0.00079)
0.01 0.01 0.01 0.01 0.01
2. Lead (Pb)
ND
(< 0.00064)
0.01 0.0157 0.01 0.01 0.01
3. Selenium (Se)
ND
(< 0.00154)
0.01 0.05 0.01 0.01 0.01
4. Chromium (Cr)
ND
(< 0.00022)
0.05 0.1 0.05
(Cr6+)
0.05 0.05
5. Cadmium (Cd)
ND
(<0.00042)
0.005 0.005 0.003 0.005 0.003
6. Barium (Ba)
0.006
(<0.00045)
2.0 2.0 - - 0.7
7. Antimony (Sb)
ND
(<0.00073)
0.01 0.006 - 0.005 0.02
8. Nickle (Ni)
ND
(< 0.00023)
0.1 - - 0.02 0.07
9. Mercury (Hg)
ND
(< 0.00008)
0.002 0.002 0.0005 0.001 0.006
10.Cyanide (CN-)
ND
(< 0.003)
0.05 0.2 0.01 0.05 -
11.NO- 2-N
(Nitrite Nitrogen, as N)
ND
(< 0.0005)
0.1 1 0.04 0.1 3
Disinfection by-product
12.Trihalomethanes (THMs)
0.0051 0.08 0.08 0.1 0.1 *8
13. Haloacetic acids
(sum of concentrations of Monochloroacetic acid(MCAA), Dichloroacetic acid, Trichloroacetic acid(DCAA), Monobromoacetic acid(MBAA) & Dibromoacetic acid(DBAA))
0.00603 0.060 0.06 0.02 (MCAA)
0.03(DCAA)
0.03(TCAA)
- 0.02 (MCAA)
0.02(TCAA)
14. Bromate
ND
(<0.00045)
0.01 0.01 0.01 0.01 0.01
15. Chlorite
ND
(<0.00082)
0.7 1 - - 0.7
Volatile Organics
16.Trichloroethylene
ND
(<0.000028)
0.005 0.005 0.01 *10 0.02
17.Carbon Tetrachloride
ND
(<0.000031)
0.005 0.005 0.002 - 0.004
18.1,1,1-Trichloroethane
ND
(<0.000023)
0.20 0.20 0.06 - -
19.1,2-Dichloroethane
ND
(<0.000036)
0.005 0.005 - 0.003 0.03
20.Vinyl chloride
ND
(<0.00033)
0.002 0.002 - 0.0005 0.0003
21.Benzene
ND
(<0.0003)
0.005 0.005 0.01 0.001 0.01
22.Para-Dichlorlbenzene
ND
(<0.000028)
0.075 0.075 - - 0.3
23.1,1-Dichloroethylene
ND
(<0.000028)
0.007 0.007 0.04 - -
24. Dichloromethane
ND
(<0.00062)
0.02 0.005 0.02 - 0.02
25. 1,2-Dichlorobenzene
ND
(<0.00035)
0.6 0.6 - - 1
26. Toluene
ND
(<0.00036)
0.7 1 - - 0.7
27. Xylenes
ND
(<0.000072)
0.5 10 - - 0.5
28.
cis-1,2-Dichloroethene
ND
(<0.00003)
0.07 0.07 0.04*9 - -
29. trans-1,2-Dichloroethene
ND
(<0.000023)
0.1 0.1 0.04*9 - -
30. Tetrachloroethene
ND
(<0.000032)
0.005 0.005 0.01 *10 0.04
Pesiticides
31.Endosulfan
ND
(<0.000003)
0.003 - - *12 -
32.Lindane
ND
(<0.0000019)
0.0002 0.0002 - *12 0.002
33.Butachlor
ND
(<0.00024)
0.02 - - *12 -
34.2.4-Dichlorooxyacetic acid
ND
(<0.00017)
0.07 0.07 - *12 0.03
35.Paraquat*11
ND
(<0.0044)
0.01 - - *12 -
36.Methomyl
ND
(<0.00239)
0.01 - - *12 -
37.Carbofuran
ND
(<0.00236)
0.02 0.04 - *12 0.007
38.Isoprocarb
ND
(<0.00249)
0.02 - - *12 -
39.Methamidophos
ND
(<0.00255)
0.02 - - *12 -
40.Diazinon
ND
(<0.00000144)
0.005 - - *12 -
41.Parathion
ND
(<0.0000026)
0.02 - - *12 -
42.EPN
ND
(<0.0000119)
0.005 - - *12 -
43.Monocrotoohos
ND
(<0.0000478)
0.003 - - *12 -
Persistent organic pollutants, POPs
44. Dioxin
(pg WHO-TEQ/L)
0.002 3 3 - - -

(B) Substances probably affecting health

1.Fluoride (F-)
0.04 0.8 4.0*13 0.8 1.5 1.5
2.NO3-N
(Nitrate Nitrogen ,As N)
0.67 10.0 10.0 10 50 50
3.Silver (Ag)
ND
(<0.00041)
0.05 0.1*5 - - -

(C)Substances affecting palatability

1.Iron (Fe)
0.001 0.3 0.3*5 0.3 0.2 0.1
2.Manganese (Mn)
0.002 0.05 0.05*5 0.05 0.05 0.05
3.Copper (Cu)
ND
(<0.00056)
1.0 1.0*5
1.3*7
1.0 2.0 2.0
4.Zinc (Zn)
0.002 5.0 5.0*5 1.0 - -
5.Sulfate (SO4-2)
10.1 250 250*5 - 250 -
6.Phenols
ND
(<0.0009)
0.001 - 0.005 - -
7.MBAS
(Anionic Surfactant, Methylene Blue Activated Substance)
ND
(<0.03)
0.5 - 0.2 - -
8.Chloride (Cl-)
7.8 250 250*5 200 250 -
9.NH3-N (Ammonia Nitrogen, As N) ND
(<0.011)
0.1 - - 0.5 -
10.Total Hardness*14, as CaCO3
37.5 300 - - - -
11.Total Dissolved Solids
65 500 500*5 500 - -
12. Aluminium (Total Al)
0.051 0.3 0.05~0.2*5 0.2 0.2 0.1

D. Residual chlorine

0.58 0.2~1.0 4 - - 0.5-1.5

E. pH value

7.2 6.0~8.5 6.5~8.5
*5
5.8~8.6 6.5~9.5 8.2~8.8
(25˚C)
ND : Non detected.
Unit : mg/l (unless specified otherwise)
*7. Lead and copper are regulated by a Treatment Technique that requires systems to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. For copper, the action level is 1.3 mg/L, and for lead is 0.015 mg/L.
*8. The sum of the ratio of the concentration of each to its respective quideline value should not exceed 1.
*9. The sum of concentration of cis-1,2-Dichloroethene and trans-1,2-Dichloroethene should not exceed 0.04 mg/L.
*10. Sum of concentrations of Tetrachloroehtene and Trichloroethene should not exceed 0.01 mg/L.
*11. paraquat (as dichloride), quivalent to 0.007 mg/L for paraquat ion.
*12 . Pesticides,each 0.0001 mg/L ,Total: 0.0005 mg/L.
*13. USEPA also set the SMCL(Secondary Maximum Contaminant Limits)as 2 mg /L for fluoride Public acceptance of hardness varies considerably.
*14. Generally, hardness levels between 80 and 100 mg/L (as CaCO3 ) are considered acceptable; levels greater than 200 mg/L are considered poor but can be tolerated; those in excess of 500 mg/L are normally considered unacceptable.