Although I hesitate to recommend it, there’s a short demo video available on Amazon as well as a few review videos on YouTube if you’re considering the Cuisinart PerfecTemp I recently reviewed. I was laughing so hard at the utter nonsense coming out of the narrator on the Amazon vid, you’d have thought it was Mad TV. Obviously unless you happen to be lucky enough to have a reverse osmosis filter in your home or office, you should not brew tea with tap water. That’s kind of the very first rule of preparing tea… I recognize belatedly that I’ve never really spoken at length as to why this is.
I wish that I had permission to quote the entire relevant page from Jane Pettigrew & Bruce Richardson’s terrific 2008 monograph The New Tea Companion: A Guide to Teas Throughout the World. It’s easily the most concise and informative guide I’ve yet seen to tea water. I think I can probably get away with a block quote though:
The type of water used for brewing plays an enormously important role in the final flavour, clarity and colour of the liquor. While a tea brewed in one particular water may taste dull and flat, the same tea brewed in water from a different location can be wonderfully brisk and bright. All the ingredients of an individual water play their part in the brewing process—the natural minerals, the added chemicals such as chlorine and fluoride, the amount of oxygen, etc…The poorest water for tea is water that has stood for any length of time and has therefore become lifeless and flat. Hard water which contains a high level of calcium is poor for most types of tea, deadening the flavour and causing a scum to form on the surface of the tea in the cup, as calcium carbonate reacts with oxygen to become calcium bicarbonate…If bottled water is used, a pH of 7 is ideal. But choose carefully since many types of bottled water contain salts and other minerals, which can spoil the flavour of the tea in the same was as can some tap water.
In addition to these insights, I’ve learned the hard way that one cannot use tap water, mineral water or spring water for long in an expensive tea kettle like a Zoujirushi without clogging the filter (and believe me, de-clogging filters is exhausting work). I would only recommend using distilled water (which some claim is too flat for tea) or purified/reverse osmosis water.
In my experience, reverse osmosis water is by far the cheapest water that’s pure enough for brewing tea to perfection. How cheap? Well, assuming you don’t have your own system in home, these enormous 2 ½ gallon (9.46 L) water jugs can usually be found at your neighborhood large grocer (at least, in the US). To buy reverse osmosis, in the water aisle look for jugs marked as “purified water” or “drinking water”. Simple spring water has not been de-mineralized and thus isn’t good for tea or expensive tea kettles. At this point I have yet to experiment with the really expensive artesian waters like Volvic for brewing, but I’m certain they’d still clog Zoujirushi filters.
Oftentimes, companies like Glacier and Primo put reverse osmosis bottle-refill stations in large grocers. I have used these refill stations for many years since they usually only cost around 39 cents USD per gallon for a refill! To make reverse osmosis refill station use easier, I believe I was able to get a hefty 3-6 gallon BPA free water drum with a handle for around $18? If used within a week, and aired out correctly, water drums can be refilled many, many times. Best of all, reverse osmosis refill stations leverage local tap water for their processing. In other words, there’s no fear that water is being wasted in the making or depleted from thirsting California plant life.
I would love to install a reverse osmosis filtration system in a future residence, but I’m thinking that’s probably preventively expensive even for me. :/