Putri Duyung (2013)

There's been multiple Indonesian TV shows titled Putri Duyung (Mermaids) and this one, which began airing in 2013, is the one that uses the premise of H2O: Just Add Water. Three teenage friends Indah, Astrid and Raya end up in an island cave and enter the water under a full moon, which gives them the ability to transform into mermaids upon contact with water, along with other magical powers.

Indah (Indah Permatasari) is Cleo i.e. the one crushed on by her guy friend Doni and who can manipulate water into shapes, Astrid (Anggika Bölsterli) is Emma i.e. the former competitive swimmer with ice powers, and Raya (Akina Fathia) is Rikki i.e. the one with water-heating powers. An important new addition is the girls' history teacher Maya (Luna Maya), who is also the Mermaid Queen, and she tells them that they can become human again if they do a thousand good deeds, and she constantly uses her powers to help them when they're in trouble, though she also gets into trouble of her own.

I haven't watched the whole 114-episode show but the first ten episodes use stories from H2O: Just Add Water, like the pool party where Doni learns about the mermaid situation, Indah's sister reads her diary and teams up with Astrid's brother to expose them, and Andi (the Zane analogue) keeps antagonizing them. But after that ten-episode mark the show seems to go firmly off in its localized direction, with stories of the girls directly using their powers to help people on their way to doing a thousand good deeds and are constantly being chased by antagonists who would capture or do them harm.