Reader CrisisMaven has a useful and informative post on what to do if there is radioactivity in the water you use. A big thumbs up to CrisisMaven and vielen Dank!. His native language (I believe) is German, but he has taken the trouble to translate his own articles into English. He invites readers and visitors to re-post (with attribution and link) and especially hopes that someone can translate this article into Japanese.
Most methods and tools being recommended here on the Internet such as purification by filtration will not lead to your desired result of decontaminating “radioactive water”.
a) Radioactive contamination of drinking water in Japan at this point in time can come about in only two ways:1) The source is actual surface water like lakes or rivers, possibly filtrated through river banks and thus came into contact with e.g. radioactive rain and/or dust. The Netherlands rely almost totally on water drawn from the Rhine and fed into the drinking water supply after conditioning.
2) The water may have been contaminated after production (e.g. in open cisterns/basins), which in effect is similar to bullet a1).
In all other cases it springs from groundwater (wells) and has often been concealed for years before being extracted again. As limnologists would say “groundwater” has an elephant’s memory, i.e. if you drop a can of used oil in a forest it may take ten years until you become aware of oil traces in your drinking water. This means that on one hand ground water wells should as a rule not yet show contamination from rain fall so shortly after a nuclear accident and on the other hand that when it appears further “down the road” all short-lived contamination should have decayed. This is by no means meant to downplay the issue.
So far I would have thought it unlikely to already find radioactive contamination in water that does not come from surface water or bank filtrate. If it should be true it would be alarming.
Now though, let’s assume it were true as authorities would rather hush up things than exaggerate them, thus let’s take some degree of water contamination for granted.
