Okay, so I'm a huge fan of H2O and I've spent hours looking for a site that you can watch it on ( ever since they took it of Youtube ). I've finally found a site that has EVERY SINGLE EPISODE of H2O ever made. It's free, and you don't have to sign up for anything. IT'S TOO GOOD TO BE TRUE! Here are the simple steps to get to it.
1) Go to www.tvduck.com
2) Go to the search and type in 'H2O Just Add Water'
3) Click on the first one that shows up (not the ones in the box)
4) When you click on an episode you want to watch it'll show a list of different websites. Click on Gloomb. That one should work every time.