Tetsubin Questions

[psoque]

Hi. I'm a Japanese American and visit Japan about once a year. I'm going there again this fall and I am seriously considering buying an authentic tetsubin and/or tetsubin-style kyusu there this time. I apologize in advance if these questions have been answered already. However as I can read, they have not been. I live in Central Indiana where the tap water is very hard (TDS of 292 ppm, CaCO3 hardness of 425 ppm). It appears our water does not have that much iron. The entire house except for the kitchen faucet is connected to a salt-based water softener. We also have a reverse osmosis filter for the kitchen which reduces TDS to 18 and CaCO3 hardness to 25 ppm. I am currently using the reverse osmosis water for both Japanese and other teas, not because it is the best option, but it is the better option brewing with tap water, which results in a horrible murky mess.

So here are my questions:

1. Which water (tap vs reverse osmosis) should I use with tetsubin? If I start boiling tap water in a traditional (non-enameled) tetsubin, would it actually make the water more compatible with brewing tea? Is the level of calcium and magnesium in the water too much for the tetsubin to handle? Would it overwhelm the kettle to the point it would near-saturate the surface with calcium and magnesium deposits?
2. On the other hand, is it totally counterproductive to use my reverse-osmosis water with the tetsubin because it only adds iron, and we need other minerals for the water to taste better?
3. Do you think I just just "cure" the tetsubin with tap (hard) water first, then use reverse osmosis for actual water for tea, and periodically "re-cure" the tetsubin with tap water? I am hoping that this would provide additional (mainly Ca and Mg) ions to the water, and it would still be relatively soft, like water in Japan.
4. I noticed on Japanese websites that in addition to traditional tetsubin (uncoated but reduced), and in addition to enamel coated kyusu (I like to call them tetsubin-style kyusu, not really a tetsubin(, there is a third kind of kyusu-sized tetsubin that is heat (and silicone??) treated to make it more appropriate for direct heating AND tea brewing. What's the story with that kind of tetsubin? They are typically sold as 急須兼用鉄瓶 (kyusu kenyo testubin, or dual-use tetsubin/kyusu). It appears you can boil water in it AND you can make tea in it, AND it adds iron to the water. It sounds too good to be true, or is it just a smaller traditional tetsubin marketed for brewing?

Thanks.

Naoyuki

[umijoshi]

Hi. I'm a Japanese American and visit Japan about once a year. I'm going there again this fall and I am seriously considering buying an authentic tetsubin and/or tetsubin-style kyusu there this time. I apologize in advance if these questions have been answered already. However as I can read, they have not been. I live in Central Indiana where the tap water is very hard (TDS of 292 ppm, CaCO3 hardness of 425 ppm). It appears our water does not have that much iron. The entire house except for the kitchen faucet is connected to a salt-based water softener. We also have a reverse osmosis filter for the kitchen which reduces TDS to 18 and CaCO3 hardness to 25 ppm. I am currently using the reverse osmosis water for both Japanese and other teas, not because it is the best option, but it is the better option brewing with tap water, which results in a horrible murky mess.

So here are my questions:

1. Which water (tap vs reverse osmosis) should I use with tetsubin? If I start boiling tap water in a traditional (non-enameled) tetsubin, would it actually make the water more compatible with brewing tea? Is the level of calcium and magnesium in the water too much for the tetsubin to handle? Would it overwhelm the kettle to the point it would near-saturate the surface with calcium and magnesium deposits?
2. On the other hand, is it totally counterproductive to use my reverse-osmosis water with the tetsubin because it only adds iron, and we need other minerals for the water to taste better?
3. Do you think I just just "cure" the tetsubin with tap (hard) water first, then use reverse osmosis for actual water for tea, and periodically "re-cure" the tetsubin with tap water? I am hoping that this would provide additional (mainly Ca and Mg) ions to the water, and it would still be relatively soft, like water in Japan.
4. I noticed on Japanese websites that in addition to traditional tetsubin (uncoated but reduced), and in addition to enamel coated kyusu (I like to call them tetsubin-style kyusu, not really a tetsubin(, there is a third kind of kyusu-sized tetsubin that is heat (and silicone??) treated to make it more appropriate for direct heating AND tea brewing. What's the story with that kind of tetsubin? They are typically sold as 急須兼用鉄瓶 (kyusu kenyo testubin, or dual-use tetsubin/kyusu). It appears you can boil water in it AND you can make tea in it, AND it adds iron to the water. It sounds too good to be true, or is it just a smaller traditional tetsubin marketed for brewing?

Thanks.

Naoyuki

1+2) RO, consider your tetsubin will give you all the elements you'll need in the water to make it suitable for good tea. I have had very unsavory experiences using tap water to brew tea (aromas, flavors, and color of the brewed tea differ from filtered water). Regarding other minerals, you can buy clay bars or storage pots to put into your water if you want to have an earthier mineral flavor. From my experience though, iron is all you need.

The surface of your tetsubin will be definitely coated with calcium precipitate, but thats not necessarily bad as it helps to prevent the iron from rusting. Embrace where you live~

Even using strongly filtered water at my workplace, my tetsubin has gained a lot of calcium carbonate over its 5 years of use.

I've never heard of the kyusu kenyo tetsubins. I think you should consider that if it is rust proof I dont think there will be any influence to your water. You can brew tea in a regular tetsubin even if its not designed for it, I think the clean up would be a pain in the ass though.

[Benheld]

I don't have better idea on tetsubin tea. But I would like to learn more about this one. Thank you!