I use the water from my ECM Giotto which is my espresso machine. It keeps the water at above 212'(!) since it's a pressure boiler for making espresso. Water sits at around 220' - 217' in the boiler at around 1.1 - 1.2 bar. I also have a zoji and can't tell the difference in taste. I use britta water both ways and it's good.
Orguz - I wouldn't use distilled for coffee or tea - no salts, no taste.. just like cooking. I would try going to your grocery store and buying the spring water in a gallon jug if you don't have a britta filter. It should make a big difference.
An interesting story... I'm a Chinese medicine practitioner and some Chinese herbal formulas from long ago call for 'lao shui' (old water - that's been standing for some time) and others call for ... uh... forgot the term, but basically it's water that's been re-ladled into the pot over 100 times. I guess that makes the water more frisky
- which should make a frisky tea!