Distilled water in Japan

  • Distilled water in Japan

    Posted by Rob Dyer on March 22, 2023 at 6:01 pm

    I have a client asking about where they can find distilled water in Japan.

    Her husband needs distilled water for an overnight breathing machine (CPAP). I googled it. The Internet says pharmacies should have it and to ask for Seisei-sui”(精製水) Does that sound right to anyone?

    I saw that it might be confused with purified water – which (apparently) is best NOT to use with CPAP machines.

    Any experienced advice on this would be much appreciated – thanks!

    AsiaMarketMakers replied 11 months, 2 weeks ago 5 Members · 10 Replies
  • 10 Replies
  • Carlos

    March 22, 2023 at 6:04 pm

    Great question!

    I also use a CPAP and have found it interesting how not all countries have it easily available, even though CPAPs are used worldwide.

    • Josh Grisdale

      March 22, 2023 at 6:51 pm

      OK, so, from what I understand, 精製水 has various types, one of which is distilled water. The correct word for distilled water is 蒸留水 – jōryūsui.

      So, I don’t think you can use just any 精製水 in the CPAP.

      I just went to the drug store to get laundry detergent and decided to take a look and they only have 精製水 without much explanation…

      So… they should at least be aware that not all are ok and should remember the kanji 蒸留水.

      Home centers etc like Momotaro should have it since it is still used in wet cell batteries etc. You can also buy it online, so they could maybe send it to their hotel?

      On Amazon they sell CPAP water! It just says 精製水 in the title but it has 蒸留水 down in the explanation.


  • Rob Dyer

    March 22, 2023 at 6:56 pm

    That’s great – thanks Josh for such a useful and comprehensive reply!

    Have passed on this info to my client.

  • SDKJapan

    March 22, 2023 at 7:16 pm


    I think Josh has already responded, but I will add what I found to be sure.
    As he noted, you can purchase distilled water branded specifically for CPAP use, but its expensive on Amazon and other online sites in Japan. I think your client could refer to the Amazon link and decide.



    FYI–=CPAP machine maket Information page:


  • Rob Dyer

    March 22, 2023 at 7:21 pm

    Thanks Scott 👍

  • Carlos

    March 22, 2023 at 7:39 pm

    According to this (from the US Embassy in Japan): https://www.us.emb-japan.go.jp/itpr_en/bringing-medications-to-japan.html , you also need to fill out this form (https://www.mhlw.go.jp/english/policy/health-medical/pharmaceuticals/dl/qa2.pdf) and be approved, in advance, by the Japanese government just to bring in a CPAP into Japan.

    Why? I don’t know. Maybe they want to make sure you’re not using it to smuggle in contraband (like drugs, etc.). Seems pretty silly to have to go through the same procedures as actual medication.

    When my friend and I went to London in 2019, I brought my CPAP and my friend brought in OTC cold medicine for personal use as easily as our own clothes.

  • Rob Dyer

    March 22, 2023 at 7:42 pm

    Thanks Carlos – but I couldn’t see any references on the website or PDF to CPAP. Did I miss something?

    • Carlos

      March 22, 2023 at 7:52 pm

      In the sample pages, it shows a “K-PAP”. Are CPAPs called K-PAP in Japan? Also, a previous link in this discussion was from one of the major CPAP manufacturers, RESMED. That link said you needed the authorization certificate.

      If there’s still some confusion, your client may want to contact the closest Japanese Consulate. (There’s one in Los Angeles, for example.) Hopefully, they’d know the procedure.

    • Rob Dyer

      March 23, 2023 at 7:52 pm

      Thanks for the clarification Carlos. Much appreciated. I will advise the client as you suggest. 👍

  • AsiaMarketMakers

    July 9, 2023 at 4:22 pm

    Contact the Japanese health department. There will be email contacts on the Japanese embassy websites in your country.

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