contaminated water

Tap water in Tokyo includes radioactive material.
As of April 4th, their values are better than WHO guidance level under bad condition,  and worse than WHO guideline for desired condition.

Radioactive materials in tap water was detected 3/16,   near place to the Fukushima nuclear plant.
(earthquake 3/11, the first explosion of reactorNo1 was 3/12, reactorNo3 explosion was 3/14, explosion of  reactorNo2 and reactorNo4 was 3/15)

So, purification plant in Tokyo started reporting radioactive material revel 3/17.

According to this pdf document;
http://www.who.int/water_sanitation_health/dwq/GDW9rev1and2.pdf
 (page 203), WHO guidance level are:

Iodine-131      10Bq/litre
Cesium-134    10Bq/litre
Cesium-137    10Bq/litre


According to this page by purification plant in Tokyo;
http://www.metro.tokyo.jp/INET/OSHIRASE/2011/03/20l3i200.htm)
WHO has another much strict guidance level;

alpha-radioactivity 0.5Bq/litre

beta radioactivity 1Bq/litre

The purification plant says they had been keeping good level last 20 years before 3/17 also.

Current Japanese guicance level which was issued  3/17 are 30time higher than WHO's value:
http://www.mhlw.go.jp/stf/houdou/2r9852000001558e-img/2r9852000001559v.pdf

Iodine-131     300Bq/Kg
Radiocesium  200Bq/Kg


As Japanese have new guideline, almost all water is SAFE in Japan, Japanese government don't have to notice how much water is contaminated.

Japanese had the same guidance level as WHO before, maybe.
http://whqlibdoc.who.int/publications/2004/9241546387_jpn.pdf
(page 203-204)



Shinjuku Tokyo

Radioactive material level in tap water in Tokyo / day

Sampling date	Iodine-131  (131I) Bq/kg	Radiocesium
		Cesium-134 （134Cs) Bq/kg	Cesium-137 （137Cs) Bq/kg
2011/04/03	2.93	0.21	0.28
2011/04/02	1.96	(ND)	0.45
2011/04/01	2.06	(ND)	0.45
2011/03/31	3.39	0.35	0.52
2011/03/30	5.09	0.25	0.63
2011/03/29	5.63	(ND)	0.51
2011/03/28	9.82	0.25	0.56
2011/03/27	19.7	0.47	0.72
2011/03/26	37.2	0.78	1.01
2011/03/25	31.8	0.92	1.22
2011/03/24	25.6	1.01	1.43
2011/03/23	25.8	0.62	0.87
2011/03/22	18.7	0.34	0.31
2011/03/21	5.25	0.23	0.22
2011/03/20	2.93	(ND)	(ND)
2011/03/19	2.85	0.15	0.21
2011/03/18	1.47	(ND)	(ND)
Japanese guideline	300Bq/kg	200Bq/kg
WHO Guidance level	10Bq/litre	10Bq/litre	10Bq/litre
WHO Guideline for water to drink	whole sum of radioactivity alpha-radioactivity 0.5Bq/litre beta radioactivity 1Bq/litre