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Water Quality and Water Resources

Today’s Water Quality

水色丸ナンバー: 131 water taps in the Tokyo Metropolitan Area
赤色四角ナンバー: Purification Plants
 For inquiries in relation to the cities of Musashino, Akishima, Hamura, and the village of Hinohara, please contact the Water Supply Departments of those local government agencies.

Click on the following chart to expand it.

Map

Dec 18(Mon), 2017

131 water taps in the Tokyo Metropolitan Area have installed automatic water quality meters. Every day at 9 a.m. we update the data obtained from the meters about “residual chlorine concentration”, “turbidity” and “color”.
*Because the data are preliminary figures, those figures may be corrected at a later date.
*From April 1, 2016, the automatic water quality meter at Station No. 45 has moved to Toyosu in Koto-KU

Residual chlorine concentration data for 131 water taps in the Tokyo Metropolitan area (as of 9 o’clock this morning.)
The numbers of each water tap, together with their locations, are shown on the map above.
Tap No. Residual chlorine concentration Tap No. Residual chlorine concentration Tap No. Residual chlorine concentration Tap No. Residual chlorine concentration Tap No. Residual chlorine concentration
1   31   61   91   121  
2   32   62   92   122  
3   33   63   93   123  
4   34   64   94   124  
5   35   65   95   125  
6   36   66   96   126  
7   37   67   97   127  
8   38   68   98   128  
9   39   69   99   129  
10   40   70   100   130  
11   41   71   101   131  
12   42   72   102   (Units::mg/L)
13   43   73   103  
14   44   74   104  
15   45   75   105  
16   46   76   106  
17   47   77   107  
18   48   78   108  
19   49   79   109  
20   50   80   110  
21   51   81   111  
22   52   82   112  
23   53   83   113  
24   54   84   114  
25   55   85   115  
26   56   86   116  
27   57   87   117  
28   58   88   118  
29   59   89   119  
30   60   90   120  

The results for turbidity and color are here.

Results for “turbidity” >>

Results for “color” >>

Explanation of Terms
Residual Chlorine

Chlorine, which is used as a disinfectant, is present in the water supply in extremely small concentrations.
Under the Waterworks Law, disinfection by chlorine is mandated for the purpose of maintaining hygiene.

Maintaining a concentration greater that the national minimum standard of 0.1mg/L is required by law, and Bureau of Waterworks Tokyo Metropolitan Government sets a target value to be maintained of between 0.1 mg/L and 0.4 mg/L.
Turbidity This indicates the degree of muddiness of water. This is a matter of judgement as to whether the water from the public water supply meets the requirement of being “almost completely colorless and transparent in appearance” according to standard criteria of 2 degrees or less. Where this is achieved, this can be called clear water, free from muddiness. However the Bureau of Waterworks Tokyo Metropolitan Government sets an ever stricter standard of no more than 0.1 degrees.
Color This shows the color of the water and this is a matter of judgement as to whether the water from the public water supply meets the criteria of being “almost completely colorless and transparent in appearance. Water whose color is no greater than the standard value (a range of 5 degrees or below) is considered colorless. However the Bureau of Waterworks Tokyo Metropolitan Government sets an even stricter standard of no more than 1 degree.
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