Levels of radioactive materials in tap water obtained everyday, 2024 Fiscal year

Drinking water samples used in this measurement are taken everyday from a tap directly connected to the water supply in the facility of the Tokyo Metropolitan Institute of Public Health.

The sampling and measurement are conducted at the Tokyo Metropolitan Institute of Public Health (Hyakunin-cho, Shinju-ku, Tokyo)

The results of the daily measurements conducted at water purification plants in the Tokyo Metropolitan area are announced on the official website of the Bureau of Waterworks.

Please see here about the principle behind “ND (Not Detectable)”

Sampling date 131I
Bq/kg
Radioactive Cesium
134Cs
Bq/kg
137Cs
Bq/kg
Tap water management target values※1 10
Reference levels established by the Nuclear Safety Commission for limiting consumption of foods and drinks※2 300 200
19 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Dec.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Nov.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
31 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Oct.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Sep.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
31 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Aug.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
31 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Jul.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Jun.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
31 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 May.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
30 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
29 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
28 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
27 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
26 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
25 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
24 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
23 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
22 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
21 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
20 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
19 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
18 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
17 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
16 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
15 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
14 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
13 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
12 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
11 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
10 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
09 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
08 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
07 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
06 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
05 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
04 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
03 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
02 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
01 Apr.,2024 ND(not detectable) ND(not detectable) ND(not detectable)
  • Samples are taken from a tap and analyzed everyday using a germanium semiconductor detector.
  • It is known that rainfall may increase values.
  • The number of significant digits of values is set as 2 in order to be consistent with that of the Japanese government.

Please see the pages for each year for data from previous surveys

  • ※1 The Ministry of Health, Labor and Welfare of Japan has set the management target values for the levels of radioactive materials in tap water as 10 Bq/kg of radioactive cesium (5. March, 2012).

    For details, please refer to the following site:
    http://www.mhlw.go.jp/stf/houdou/2r98520000018ndf.html

  • ※2 The Nuclear Safety Commission (now the Nuclear Regulation Authority) of Japan has showed reference levels regarding the limiting consumption of food and drink (June 1980, Last revised in 2010) . The reference level of radioactive iodine (typical isotope: 131I ) and radioactive cesium for drinking water are 300 Bq/kg or higher, and 200 Bq/kg or higher, respectively.

    For details, please refer to the following:
    http://www.nsr.go.jp/archive/nsc/anzen/sonota/houkoku/bousai220823.pdf