An animated TV show about a family of immortal kids kept alive by tea leaves

I remember watching a TV series maybe 15-20 years ago (around 2000-05?) that was about an immortal/very-long-lived family (on a farm?). I’m pretty sure it was a TV series, but it may have just been a long show (maybe a movie, but I doubt it).

• They were all kept really young because they grew and made tea with special tea leaves.
• I watched it when I was in Australia. I don’t remember where the story was based.
• I seem to remember there was a lot of the colour
  blue in the show too? I think the tea was blue.
• I remember the story was pretty dark, but not
  gruesome or horror. Kind of creepy and mysterious.
• I think the animation visual style was kind of
  similar to the Gorillaz older art style.
• I’m pretty sure all (or most) characters were "white", and there were males and females.
• I think there were multiple generations of the family there. i.e. Kids through to grandparents. I remember that I got confused because they all looked the same age.
• I just remembered: I think the tea actually REVERSED their age, not just stopped them aging, because I vaguely remember a grandparent at one point that was younger than the kids temporarily because of a missed dose of tea or something.