Drinking water in Japan

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Health Canada and the Canadian Food Inspection Agency are in regular contact with Japanese authorities and will continue to provide information to Canadians as the situation evolves. Japanese and international authorities have put in place monitoring programs to identify radioactivity levels in water.

Monitoring of drinking water is on-going: iodine-131 in drinking water was detected on March 28 in 9 prefectures, whereas caesium-137 was detected in 6 of the 47 prefectures. The majority of the recently measured radioactivity levels in drinking water are being reported below the levels established by the Japanese authorities which are 100 Bq/L of I-131 for infants; 300 Bq/L for adults and 200 Bq/L of Cs-137 for infants and adults. Previously imposed recommendations for restrictions on drinking water are being lifted in most of the affected locations. As of 28 March, recommendations for restrictions based on I-131 concentration remain in place for Iatate-mura in Fukushima prefecture. In three other locations of the Fukushima prefectures (i.e., Date-Shi, Minamisoma-shi, and Iwak-shi), restrictions continue to apply for infants only.

As of  April 2, only one of these drinking water restrictions remained in place (Iitate village). This restriction applied to infants only and was in effect as a precautionary measure by the local authority, as the measurements were below the 100‑becquerel‑per‑litre restriction for intake by infants. (Source: IAEA Incident and Emergency Centre, April 4, 2011).

Reported levels of contamination in tap water in Central Tokyo, as currently reported by MEXT are provided below. The recent downward trend in both I-131 and Cs-137 concentrations is maintained.

Table 1 - Drinking water in Japan
Collected date I-131 (Bq/kg) Cs-137 (Bq/kg)
11/04/20 0.19 Not detectable
11/04/19 0.29 Not detectable
11/04/18 0.22 0.21
11/04/17 0.2 Not detectable
11/04/16 0.3 Not detectable
11/04/15 Not reported Not reported
11/04/14 0.41 Not detectable
11/04/13 0.41 0.26
11/04/12 0.57 Not detectable
11/04/11 0.6 0.27
11/04/10 0.71 Not detectable
11/04/09 1.0 0.26
11/04/08 0.9 0.48
11/04/07 1.4 0.6
11/04/06 1.6 0.5
11/04/05 2.6 0.64
11/04/04 3.8 0.59
11/04/03 2.9 0.5
11/04/02 2 0.45
11/04/01 2.1 0.45
~ ~ ~
11/03/31 3.4 0.88
11/03/30 5.1 0.9
11/03/29 5.6 0.51
11/03/28 9.8 0.82
11/03/27 20 1.2
11/03/26 37 1.8
11/03/25 32 2.1
11/03/24 25.6 2.4
11/03/23 26 1.5
11/03/22 19 0.31
11/03/21 5.3 0.22
11/03/20 2.9 Not detectable
11/03/19 2.9 0.21
11/03/18 1.5 Not detectable

Source - http://www.mext.go.jp/english/

It is also noted that both Cs-137 and I-131 concentrations being reported in drinking water in Japan would now meet the Canadian Guidelines on Drinking Water Quality which are the guidelines used across Canada as the basis for establishing the non-emergency drinking water quality requirements for people living in Canada.  (DFAIT March 31, 2011).

For more information on the safety of Japanese drinking water, food and the environment, please visit the Japanese Ministry of Agriculture, Forestry and Fisheries (MAFF).