Japanese have been told that tap water is contaminated. They’ve also been told not to feed the water to their babies.

The level of contamination is too high for infants.  The contamination is mainly short life span Iodine-131.  Iodine-131 collects on your thyroid gland, and can cause cancer.

The Japanese government will be issuing clean water to parents with infants, who are, I believe they said, 12 months and younger.

Some people think they can boil the water. The problem is that the radioactive isotopes in the water then become air born in the steam rising from the boiling water, and you breath them in.  Also, if you boil for a only a short time there will still be contamination in the water.

The Consumer’s Guide has a web page that explains how to make water safe to drink. Scroll down until you get to the title “More Rigorous Purification Methods”. This section talks about distilling to get rid of radiation fallout in water.  It’s more complicated than just boiling.  When you distill you’re basically capturing the steam rising off the boiling water, then funneling it into a cup, or pot, to collect it.  The article then suggests you filter the water as well.