I just read a bit about using tap water for coffee on some japanese pages. It seems that most tap water in Japa,n including the one in Tokyo is very soft. They do mention the problem with chlorine which worsens when the water is heated. But like other members mentioned a charcoal filter will solve this problem. There are adapters availble which you install right on the tap and according to the pages I read they work well. I guess there will also be solutions for direct plumbing.
I would look for solutions in Japan since they are adapted to the local needs and often far ahead of what we get in the west

For instance they solved the problem with even water distribution in coffee makers over 40 years ago
http://www.youtube.com/watch?v=r2pbaQCetWI

Sounds reasonable to me for limescale risk. To be confident about long term corrosion risk it would still be good to know how much chloride ion is in that Tokyo water.

Thanks, I will keep trying to look into it.

Marmot wrote:I just read a bit about using tap water for coffee on some japanese pages. It seems that most tap water in Japa,n including the one in Tokyo is very soft. They do mention the problem with chlorine which worsens when the water is heated. But like other members mentioned a charcoal filter will solve this problem. There are adapters availble which you install right on the tap and according to the pages I read they work well. I guess there will also be solutions for direct plumbing.
I would look for solutions in Japan since they are adapted to the local needs and often far ahead of what we get in the west

Thanks!

Marmot wrote:For instance they solved the problem with even water distribution in coffee makers over 40 years ago
video

That was American technology from the 1950s!

Haha, you're right! I should have remembered that design as well. Looks like they waited for the patent to run out