A type of protozoon called Cryptosporidium [Link] has been detected from drinking water source since last year in Nagano. It causes parasitic disease but can’t be chlorinated.
The environment department of Nagano prefecture reported they detected Cryptosporidium at 6 water purification plant at least. It hasn’t been detected since October of 2000.
There is no health problem reported so far, but those 6 plants don’t have houses or farming facility, the cause is not verified yet. Cryptosporidium is usually caused by excreta of human or cattle.
5 of those 6 plants take measures such as controlling turbidity, using membrane process or alternative water source, but 1 of the plants stopped supplying drinking water. They are supplying 10 houses with plastic containers.
Iori Mochizuki