You can find it on youtube. They have each episode in different parts and they are free to watch.
Your local library probably has it!
http://vids.tv/H2O-Just-Add-Water/tv/season-2/episode-12-Monster
The last episode of H2O:Just add water is season 3 episode 26 and it is called graduation.
this site here has most links to episodes of season 1 and 2, just scroll down til u reach them: http://www.sidereel.com/H2O:_Just_Add_Water but they do not have all, just most, lol. im still looking for episode 18 of season 1 and episode 14 of season 2
All of the episodes are on free-tv-video-online.info search for h2o just add water :)
this site here has most links to episodes of season 1 and 2, just scroll down til u reach them: http://www.sidereel.com/H2O:_Just_Add_Water but they do not have all, just most, lol. im still looking for episode 18 of season 1 and episode 14 of season 2
Season 2, episode 2: "Control"
you can just go on the official site: noordinarygirlmoonspell.webs.com
You can buy it on Ebay (the series). Or you can watch it on the computer like on Netflix or Hulu.
this site here has most links to episodes of season 1 and 2, just scroll down til u reach them: http://www.sidereel.com/H2O:_Just_Add_Water but they do not have all, just most, lol. im still looking for episode 18 of season 1 and episode 14 of season 2
its season five, episode 46. Hope I helped! :)