List of H2O: Just Add Water episodes

The following is an episode list for the Australian television show H₂O: Just Add Water, which airs on Network Ten, Disney Channel Australia, Nickelodeon, Nickelodeon UK and other television networks worldwide. The series premiered on 7 July 2006, and series two concluded on 21 March 2008. A third series is planned for early 2009.

Overview

Season		Episodes	Originally Aired		DVD Release
			Season premiere	Season finale	Volume 1	Volume 2	Volume 3	Volume 4	Volume 5	Volume 6
	1	26	July 7, 2006	December 29, 2006	September 12, 2007	September 12, 2007	March 5, 2008	May 7, 2008	July 7, 2008	November 5, 2008
	2	26	September 28, 2007	March 21, 2008	TBA	TBA	TBA	TBA	TBA	TBA
	3	26	2009	2009	TBA	TBA	TBA	TBA	TBA	TBA

Episode list

Series one: 2006

Three girls, Cleo Sertori, Emma Gilbert and Rikki Chadwick, accidentally find themselves on Mako Island where they are tranformed into mermaids by the full moon in a pool of water under a volcano. They discover their amazing powers over water - Cleo can control the shape and volume of water, Emma can freeze it, and Rikki can boil it. Lewis McCartney, a friend of the girls, helps them avoid being exposed. The season is mainly about the girls' learning to control their powers well, learning about love, and dealing with everyday problems, such as pesky siblings. In the final episode of the season, Rikki's boyfriend, Zane, helps to capture the mermaids without realizing one of them is his girlfriend. When he realizes what he's done, Zane works with Lewis to release the girls, who trick the scientists into believing they've given up their powers to the lunar eclipse while they have actually only gone for twelve hours.

Episode	Title	Original airdate	Production code
01	"Metamorphosis"	7 July 2006	101
When Zane Bennett, the town's bad boy, plays a prank on Cleo Sertori with his unwanted boat, Rikki Chadwick comes to her rescue with the spark plug she stole from Zane and gets the boat going. Rikki and Cleo quickly become friends, and along the way, Emma Gilbert, Cleo's friend who's very talented at swimming, tags along. When the boat stops moving the girls are forced to paddle to the avoided Mako Island, where Emma manages to find a way out through swimming. All three jump into the pool, when the moon comes up over them and makes the water glow. Unaware that they have been turned into mermaids, the girls swim out; the following day, Emma discovers her new ability at the beach, Cleo sees her tail in the bathtub, and Rikki finds hers when she's accidentally splashed by a sprinkler. Cleo also discovers a new power over water movement when Zane tries to scare her and she makes a fire hydrant explode on him; Emma finds she can freeze water when she puts up a hand to stop one of Cleo's water creations from hitting her; Rikki believes she has no power when she's unable to control a glass of water. All girls are fully aware that this experience will transform their lives and their friendship forever.
02	"Pool Party"	14 July 2006	102
Despite knowing what water can do, the temptation of Miriam's pool party proves too strong for Cleo. At the JuiceNet Cafe, Rikki discovers her power when she heats a glass of Coke while angrily discussing Cleo with Lewis. At the pool party, out of revenge, Zane and his friends toss Cleo into Miriam's swimming pool; everybody leaves but Lewis, who discovers Cleo's mermaidness and aids her in getting out of the pool. Emma and Rikki realize Cleo is at the pool party. Emma freezes the door so as to not let anyone get out and see Cleo in mermaid form. Rikki helps Cleo turn back into a girl with her new heating power and her friends congratulate her upon her new discovery. As Lewis and the girls leave, Rikki heats up Miriam's pool, causing it to evaporate and ruin the cruel Miriam's pool party. Lewis promises not to reveal the secret.
03	"A Good Day For Fishing"	21 July 2006	103
Cleo does not share her friends' enthusiasm for their new-found abilities. Rikki and Emma's efforts to rescue sea turtles, which are trapped in fishing nets, cause a media frenzy about sharks patrolling the nearby waters. Believing her father to be involved, Cleo takes it upon herself to go after the boat responsible for the illegal fishing practices and discovers it is the fault of her father's workers, not her father, who was catching turtles. To her shock, Cleo finds herself caught in a net. Emma and Rikki save her and Cleo explains her discovery of to her father. Her father's worker is caught and brought to justice. Later, she shows Emma, Rikki and Lewis she can swim and hold her breath.
04	"Party Girls"	28 July 2006	104
Emma travels back to Mako Island where she finds a mysterious locket at the bottom of the moonpool. The risks associated with Cleo's new job at the marine park give her friends cause for concern but Cleo's determination to lead a normal life helps convince Emma to set aside her own concerns and go ahead with her annual sleepover party. Lewis conducts experiments on the moon pool at Mako Island to determine what will change the girls. Miss Chatham makes her first appearance by giving hints to Cleo about her mermaidness when Cleo got splashed by one of the fish that were supposed to be fed to the dolphins. Cleo accidentally touches water at the sleepover but hides herself in a sleeping bag; she saves the others from feeling her tail by making the drinks explode, just as Miriam was about to steal Emma's locket. Rikki catches Miriam with the locket, takes it back, and gives it to Emma, who in return gives it to Cleo. She does this based on the belief that a mermaid who can hide her tail so well can surely take good care of so valuable a locket.
05	"Something Fishy"	4 August 2006	105
Cleo's secret diary falls into her sister Kim's hands and Kim's suspicions quickly grow into a plot to expose Cleo and rest of what she calls the "evil mermaids" and shares her "secret" with Emma's brother Elliot, who quickly believes her when his shower turns into ice when Emma accidentally puts her hand up to the doorway. Cleo, Rikki, Emma, and Lewis quickly turn the kids' suspicions to Miriam, who Kim thinks is the leader of the pack. Together, Kim and Emma's little brother Elliot, plots to expose all the mermaids during the Miss Sea Queen pageant. Cleo, who is on the stage dressed as a jellyfish, protects herself with her power while Miriam's and the other girls' costumes are ruined. Lewis travels to Mako Island to try to find out the cause of the girls' transformation.
06	"Young Love"	11 August 2006	106
While babysitting Emma's brother Elliot, Rikki risks exposing her secret when he gets into trouble surfing and is forced to try to save him from drowning. The girls turn to Lewis for advice when Elliot develops a crush on Rikki but the abrasive Rikki has a hard time letting him down gently, resulting in him running away. When Rikki finds him to apologies, however, she risks revealing the mermaid secret to him by almost being locked in a green house that was about to water its plants.
07	"Moon Spell"	18 August 2006	107
Miss Chatham forewarns Cleo to not look at the full moon, but the girls scorn her warning on the basis that they are mermaids, not werewolves. Emma throws a birthday party for her dad, but forgets everything and loses her inhibitions when a full moon strikes and she sees its reflection in a bowl of punch. She is unusually rude to the guests and devours all the food prepared for the party when her friends try to hide her from the guests. Additionally, her mermaid tail will not go away after she touches water; however, when the full moon goes down, the tail vanishes along with Emma's memory of what happened that night. The girls learn that the full moon is a true danger to them and begin wondering who this mysterious Miss Chatham truly is.
08	"The Denman Affair"	25 August 2006	108
The girls reluctantly agree to let Lewis get a research assistant's position with a marine biologist, hoping to determine what's behind their transformation. They are concerned when Cleo notices Lewis has a crush on Dr. Denman. Lewis forgets a DNA sample from Cleo, which is discovered by Dr. Denman who in turn offers Lewis a lucrative job. He needs to make a choice: What is it he wants - money, or loyalty to the girls?
09	"Dangerous Waters"	1 September 2006	109
One of Cleo's fish has died. Rikki, in the attempt to make up for her brusquness, tries to find her a replacement fish. She uses her mermaidness to her advantage by diving where no fish collecter can dive and picking out a fish that resembles Cleo's lost one. She meets a man who offers her to pay her well if she sells him fish like the one she was bringing to Cleo. Rikki agrees, believing that the man is what he says he is (a marine park breeder of rare fish), but when she learns the man who hired her is lying and actually is selling the fish illegally to earn large profits, she takes it upon herself to get revenge and deliver him to the authorities.
10	"The Camera Never Lies"	8 September 2006	110
A short film contest on the subject of heroes captures the focus of the girls' attention, but a film about Emma's mother is not Rikki's idea of fun and she decides to use her abilities to capture some impressive underwater footage. Ineligible to compete himself, Zane recruits Lewis to document a recreation of his father's famous windsurfing trip to Mako Island and gets trapped by sharks on the shore. Luckily, Rikki was also there filming her "masterpiece" and manages to scare the sharks away with her powers.
11	"Sink or Swim"	15 September 2006	111
Byron asks Emma for training help prior to the school swimming meet. After initially turning him down, she changes her mind but becomes a "heavy training dragon", to Byron's disappointment. Lewis continues his experiments on the girls but Rikki does not like being treated like a specimen and does her best to disrupt his research. Emma and Byron end up kissing, but Emma dumps Byron, believing that coaches should not kiss their students. It turns out that Byron is versing Zane; though Emma swore she wouldn't attend the race, she comes anyway and watches Byron defeat Zane in the race.
12	"The Siren Effect"	22 September 2006	112
Another full moon approaches. Before nightfall, Rikki enters Cleo up for a karaoke contest, not realizing that she has no ability to sing and Cleo humiliates herself in front of everybody listening. That night, Lewis and the mermaids sleep at Cleo's house to try avoiding the full moon; while in the bathroom Cleo glimpses the full moon in a reflection, touches the water bearing it and is suddenly able to sing better than any other girl in town. Lewis realizes she's become a siren, one of those ancient, mythological mermaids whose voices lured sailors to their deaths. As with Emma's experience, Cleo's unstoppable under the moon and manages to get her voice on radio. In the morning, Cleo, to her father's irritation, escapes to the JuiceNet cafe and sings in front of all the town's boys; the full moon sinks, causing Cleo's wonderful voice to go with it, along with her brief burst of popularity.
13	"Shipwrecked"	28 September 2006	113
When Zane causes the enigmatic Miss Chatham to be evicted from her boat, Emma invites her to stay at her home. Overhearing her concern for her "treasure", Zane chases after Miss Chatham seeking compensation for his damaged jet ski when she departs the marina in her boat. Zane attacks Miss Chatham and she passes out. Emma and Lewis arrive in time to help with a medical emergency but when Zane gets trapped on the sinking boat, Emma must risk being seen as a mermaid to save him. Emma uses her tail to break open the boat's door, and Zane sees her tail. After he passes out, Emma takes him to Mako Island, where he wakes up and makes a vow to find out what it was that saved him. Emma gives Miss Chatham her treasure, which is a locket. Miss Chatham moves to a retirement home.
14	"Surprise!"	6 October 2006	114
Cleo is counting the days until her sixteenth birthday, fully aware that her big day can only be ruined by one thing: another of her father's embarrassing birthday parties. Zane embarks on a hunt for the "sea monster" he saw when he nearly drowned and recruits Lewis to help, but Lewis has promised the girls to do everything he can to keep Zane well away from them and Mako Island. Cleo is upset for watching the childish party and escapes to Mako Island, but Lewis and Zane are there. Lewis spots Cleo and tries to stop Zane from seeing her as a mermaid. Lewis and the others have a party at the JuiceNet café for Cleo.
15	"The Big Chill"	13 October 2006	115
Emma is excelling at her new job at the JuiceNet café, but when Wilfred leaves her in charge for an entire weekend, her no-nonsense managerial style puts her at odds with her newest employee: Rikki. When Zane and Miriam come into the cafe for a drink, Rikki brings Miriam the wrong drink and irritates and thanks to that she quits. In retaliation, Miriam sneaks into the café's freezer and turns the temperature up. Emma arrives, and upon noticing the freezer open and warming up, uses her powers to freeze the contents, which includes Miriam, who has hidden inside. Despite the animosity between Rikki and Emma, the girls work together - Rikki slowly melts the ice while Cleo gets the bodily fluids moving - before Wilfred returns.
16	"Lovesick"	20 October 2006	116
Cleo attracts the attention of a new dolphin at the marine park. Zane Bennett, in his attempt to find out what "monster" saved him, convinces Cleo that he needs the marine park's library in order to learn more about dying species of wild sea creatures. Cleo's friends and family mistakenly believe that Cleo is calling a boyfriend when speaking with Zane; when Mr. Sertori grounds Cleo, Kim eavesdrops on her older sister while she's speaking on the phone and draws the conclusion that Cleo's going to elope. Lewis, Emma, Rikki, and the Sertoris come just as Zane and Cleo are kneeling in front of a marine park manager, learning about dolphins' habits, and learn that Cleo had only been trying to help a sick dolphin.
17	"Under the Weather"	27 October 2006	117
A sudden thunderstorm forces the girls to feign illness to stay home from school. Doctors believe this is a "rare topical disease" when Rikki gives the girls blotches and high temperatures before Emma gives them low temperatures. Kim suspects that the girls are faking it but has no proof until the girls are about to be taken to the hospital; Emma lies and says they had pretended to be sick so they could avoid a biology test.
18	"Bad Moon Rising"	3 November 2006	118
Yet another full moon is approaching. Haunted by his encounter with the "sea monster", Zane steps up his investigation, which leads him to Mako Island. Rikki catches a glimpse of the full moon's reflection, causing her to lose control of her power. Rikki escapes Emma's house to go to Mako Island, and later Zane arrives when he sees fire. After they find each other on the island, Rikki kisses Zane, causing him to pass out from dehydration. Emma, Cleo and Lewis followed Rikki to Mako and find her sitting beside Zane, who has no memory of that day's events. Rikki is taken to the moon pool, where the moon finally leaves the sky and Rikki realizes that for the first time, she saw the full moon and she's not invulnerable to its attacks. The next morning Zane confronts Rikki about the kiss infront of Cleo, but having no memory of it Rikki simply tells Zane to forget about it.
19	"Hurricane Angela"	10 November 2006	119
The arrival of Cleo's cousin Angela is seen by the girl's father as an opportunity for Cleo to learn some maturity and responsibility. However, chaperoning a headstrong girl with a fondness for water quickly brings on its challenges - especially when the girls find they have stolen possessions, a lost cousin and a pelican in their house.
20	"Hook, Line and Sinker"	17 November 2006	120
Lewis' excitement about testing his odd new lure in the annual fishing derby is quelled by Cleo's refusal to renew their traditional partnership for fear of getting wet. Lewis is unable to catch any fish as his lure is hugely ineffective; Cleo, who's noticed that she has a crush on Lewis, tries to help by finding an absurdly huge fish in the ocean and hooking it up to Lewis's lure. This results in Lewis's disqualification, though he managed to sell several of his lures to other fishermen first. Meanwhile, Rikki and Zane encounter one another at a business seminar and get trapped on a balcony. The time alone together allows them to get to know one another better. Zane stands up to his father for the first time. In the end, Rikki and Zane learn their feelings for each other for the first time, and Lewis is allowed to return to the contest and wins when Emma and Cleo rectify Cleo's mistake by putting large fish on the other Lewis-made lures, causing Mr. Sertori to believe the lures truly do catch large fish.
21	"Red Herring"	24 November 2006	121
An innocent comment about her dependable nature convinces Emma she needs a change, so she decides to colour her hair red. The girls discover that as dying hair involves water, resulting to mermaid transformation, Emma only has red hair when she has her tail. Zane's sea monster investigation leads him to Miss Chatham who he's convinced is at the center of the mystery. When trying to find more research on the "monster", Zane spots a mermaid with red hair near Miss Chatham's boat; this was Emma trying to fetch pictures of Miss Chatham with her mermaid friends before Zane got to them. Nobody believes Zane's absurd tale. Afterwards, Rikki tracks Zane down and agrees to go out with him as long as he stops his mermaid hunt.
22	"Fish Out of Water"	1 December 2006	122
When at the movies, Cleo and Emma spot Zane and Rikki on a date and find out that they are going out. Concerned that Zane will find out their secret, Emma gives Rikki an ultimatum: her and Cleo, or Zane. Rikki believes "friends don't give friends ultimatums" and refuses to choose. Harrison Bennett's unveiling of plans to develop Mako Island realigns feelings as Emma joins Rikki's vocal opposition and Zane once again takes a stand against his father, causing the Mako-renovation plan to be destroyed.
23	"In Too Deep"	8 December 2006	123
History may be repeating itself as Rikki's ability to keep the girls' secret is tested when she discovers a locket almost identical to Miss Chatham's in a jeweller's shop. She desperately wants the locket but is unable to tell Zane why it is so important at risk of revealing the girls' secret. Zane lets slip that Rikki wants the locket when he sees Miriam; since the two girls are rivals, the wealtheier Miriam buys it first. Zane realizes how badly Rikki wants it and tries to get it back from her in exchange for a kiss. Miriam manages to find a loophole in her promise and tosses it into the water instead when Zane tells her that they never were a couple. Zane fetches the locket and gives it back to Rikki - who, of course, heats it to get rid of the water before taking it. She offers to give it back to Miss Chatham, who refuses, saying it's right for the lockets to be together. Miss Chatham gives her own locket to Emma; Emma's locket is Miss Chatham's, Cleo's is Gracie's, and Rikki's is Julia's.
24	"Love Potion #9"	15 December 2006	124
With the school dance approaching, Emma and Cleo are fretting about having to ask Byron and Lewis to go with them, relying on the boys to make the first move. But Byron does not ask Emma, who he thinks is too busy heading up the organising committee, and Lewis is too caught up in his work on a new scientific way to make it easier for the girls to be mermaids, by making them waterproof; however, the formula backfires and makes the girls redden, forcing them to leave the dance or risk humiliation. Emma gets upset when she sees Byron with Miriam at the dance before Lewis reveals that Miriam had asked Byron, not the other way around. Rikki believes Zane left her for another girl until Lewis says he's still waiting for her. Lewis admits to Cleo he'd forgotten about the dance and apologizes; for the first time they reveal their feelings for each other and become a couple.
25	"Dr Danger"	22 December 2006	125
Emma's family is planning a trip to a resort where Emma will have to go swimming, so she has no choice but to refuse to go - which irritates her parents and causes animosity between them. The return of marine biologist Dr Denman concerns Lewis and the girls but Zane sees a possible ally (or worse, a competitor) in the search for his mermaid and approaches her for help. Dr. Denman finds onen of Cleo's scales from her tail and realizes it's identical to the one Lewis left behind awhile before in her lab. She also finds the heart Lewis carved into the sand by the moon pool and makes the connection, realizing the owner of the scale is no ordinary fish. She attempts to badger information out of Lewis, thoroughly convinced that Lewis is strongly connected to the scale she found, while feeding wrong information to Zane, leading him to believe that she is approaching information on the mermaid Zane is positive he saw. Rikki accidentally tips Zane off on the fact that there are mermaids, which grows into a fierce argument and Zane yelling at Rikki to never see him again. Meanwhile, Dr. Denman sets up underwater cameras and detectors, leading to photos of the mermaids while swimming. Dr. Denman gets perilously close to the secret while the girls try frantically to hide their secret and not allow the scientists to expose them. Their efforts are in vain; when Mr. Bennett, Zane's father, finds a picture of the girls with their faces - and tails! - the scientists are bent on finding them, capturing them and will not give up.
26	"A Twist in the Tail"	29 December 2006	126
The hunt for the now identified mermaids intensifies as Dr Denman sets a trap for Cleo, Emma, and Rikki at Mako Island, then forcing Zane to make a decision about where his loyalties lie: with his father or with Rikki. A lunar eclipse also gives the girls an opportunity to free themselves from further pursuit by losing their powers, forever. While they are led to believe this is permanent, they eventually discover that the effects of the lunar eclipse has only lasted for twelve hours.

Series two: 2007-2008

The girls discover their new powers after being affected by the full moon. A new girl named Charlotte appears. Charlotte trys to steal Lewis from Cleo. Cleo breaks up with Lewis and he starts dating with Charlotte. Emma meets Ash and flirts with him, but she gives him lots of secrets. Rikki and Zane got back together. The girls learn all about full moon. Charlotte finds out all too and becomes the new mermaid with the all powers of the girls. On the another day of the full moon, Charlotte loses her powers forever. Emma reveals to Ash she's a mermaid.

Episode	Title	Original airdate	Production code
27	"Control"	28 September 2007	201
It's the night of a full moon, and all three girls accidentally see it when they open Emma's door. Under its spell, they swim to Mako Island, with Lewis in pursuit. The moon pool enhances their powers due to a special planetary alignment. Rikki is now able to control lightning and fire; Emma can freeze anything, even without water, as well as blizzards and, to some extent, the weather; and Cleo has acquired power over winds. Under the spell of the moon, together they create a powerful tempest and attack Lewis. The next day, the girls are surprised when they discover their new powers. Upon arriving at Mako Island, they discover Lewis, who explains everything. The girls must work to control these new abilities. Meanwhile, Cleo's parents have divorced, and Cleo is outraged when her father says she must start watching over her sister Kim, starting with a concert.
28	"Fire and Ice"	5 October 2007	202
Lewis has little success when he decides to test the girls' new and unpredictable powers. Emma helps her brother Elliot deal with a meddlesome teammate. Lewis' constant attention is driving Cleo crazy, leading to a frank discussion about their relationship. Meanwhile, at school Cleo accidentally wets a new girl called Charlotte with her powers, then Lewis comes and Cleo introduces her to him. Charlotte is attracted to him straight away. By Charlotte's Japanese paint, the girls learn to control their powers.
29	"Double Trouble"	12 October 2007	203
Zane's reappearance forces Rikki to decide if staying away from him is what she really wants. Can Rikki become involved with Zane again and still keep her secret? As Lewis' new friendship with Charlotte grows to Cleo's dismay, so do Cleo's suspicions about her, but she insists it has nothing to do with jealousy. As repeatedly embarrasses herself trying to reveal to Lewis that she is not as she seems, out of this Charlotte starts to create a negative relationship with Cleo as her and Lewis become closer.
30	"Emma Rebel"	19 October 2007	204
With Emma's parents away for the weekend, Rikki comes over to stay but her behaviour rubs off on Emma, who decides to prove that she too can be a rebel. But is she trying too hard? And can she handle the consequences that come with throwing a party? Lewis tries to become more manly when Nate tells him it may have been why Cleo broke up with him. Cleo gets a secret admirer.
31	"Hocus Pocus"	26 October 2007	205
When Lewis presents the girls with a rare book he discovered about mermaid mythology, Rikki and Emma reluctantly agree to help Lewis and Cleo make a potion that will give the girls the power to grant wishes. For Cleo it's an opportunity to reunite her fractured family, but when the project grows out of control, they must act quickly to clean up the café before Wilfred arrives to shoot a commercial. Charlotte is worried about Lewis spending time with Cleo as her crush on him grows stronger.
32	"Pressure Cooker"	2 November 2007	206
Cleo becomes concerned with Lewis spending time with Charlotte. Lewis insists things between them aren't as they appear, but perhaps he needs to tell that to Charlotte, who is convinced that he's not over Cleo. To make matters worse, Cleo's dad has invited a woman over for dinner. And just when it appears that welcoming a potential stepmother is the worst of Cleo's troubles, she meets her daughter...Charlotte! When Lewis comes over to convince Cleo that there is nothing going on between Charlotte and him, Charlotte tries to convince Cleo that they are dating and flirts with Lewis. Which causes a new enemy and a lost friend.
33	"In Hot Water"	9 November 2007	207
In need of money for a new computer, Lewis decides it is time he finds a job, and as luck would have it, a position becomes available at the aquarium when Cleo is fired. In an effort to help get Cleo her job back, Rikki and Emma set out to prove that serving ice-cream can be the hardest job in the world. But when the the aquarium's star attraction called Ronnie goes missing, Lewis becomes the prime suspect. Emma and Rikki feels they're the blame for Ronnie's disappearance. When Emma and Rikki fails the search, Lewis tells Cleo the blame are Emma and Rikki. Cleo yells at Emma and Rikki and they explain all to Cleo. The girls returns Ronnie to aquarium. The boss apologizes to Lewis, and gives Cleo her job back.
34	"Wrong Side of the Tracks"	16 November 2007	208
Rikki is embarrassed to tell her friends and Zane where she lives. When Nate and Zane are out riding, Nate steals a tag off Rikki's father's motorbike. Zane is seen when Nate drives off. Zane pressures Rikki to let him meet her father. After much persuasion Rikki takes him to where she lives. He has no problem with it but when he leans in to kiss her, her father catches him and throws him out. Meanwhile Cleo is dealing with a problem concerning Charlotte and Lewis' jacket, Charlotte asks Cleo to return Lewis' jacket to purposely upset Cleo, Lewis tries to convince Charlotte that they are only friends but she consists that he is wrong and will do anything to make Cleo jealous.
35	"Riding for a Fall"	23 November 2007	209
Emma is forced to take her brother Elliot for riding lessons by her mother. She gets jealous of the riding instructor Ash because he is better than her. Ash asks Emma to leave his horse Rebel to graze and warns her not to let the horse graze on the front yard because of weeds but Rebel does without her seeing. Rebel is poisoned and Emma helps him recover by using her powers. Meanwhile, Lewis is nominated for a prize and invites Cleo, but she thinks it is not a good idea since that they are only friends now, but with Charlotte desperate for wanting to go out with him she invites herself along leading to Lewis to lie to both girls.
36	"Unfathomable"	30 November 2007	210
Cleo fails the biology exam and she must study in entire weekend to correct test what starts in Monday. Cleo must have a help in study, but the helper is Charlotte, not Lewis. While Cleo is studying, Charlotte asks Lewis to bring her to Mako Island to sketch the island. When Charlotte arrives to help Cleo, Cleo finds out Charlotte has given Cleo more homework, so she can spend more time with Lewis. Lewis and Charlotte arrive at Mako Island, but they're followed by the girls. Charlotte tries to make a move on Lewis but he tries to tell her that are only friends but is interrupted by Cleo who accidentally fell from a rock to the water and Charlotte hears. Lewis spots Cleo as a mermaid and stops Charlotte to see Cleo as a mermaid. Charlotte mistakes Lewis actions and kisses Lewis, which makes Cleo angry. The next day, Cleo finally took the exam, and passed, at the Juice net Charlotte makes Cleo apologize for everything that she has done, and Lewis tries to tell Cleo the truth but fed up with his relationship with Charlotte, Cleo tells Lewis he do what ever he wants.
37	"Treasure Hunt"	7 December 2007	211
Pressured by tight family finances and the promise of a big reward, Rikki agrees to help Zane search the ocean floor for a valuable lost statue. But when she involves Emma and Cleo without telling them the full story, she finds herself alone in a dangerous situation when the truth comes out. Meanwhile, Lewis reassures the girls that he will still be there for them, but when Emma calls Lewis on Cleo's phone, Charlotte sees and hang up. Annoyed at Rikki, Emma and Cleo go to the Juice net and bump into Lewis and Charlotte, Emma receives a phone call from Zane saying that Rikki is hurt and they run off to help her, Lewis is about to go but Charlotte stops him saying that he is only ment to care for her now, fed up with her attitude Lewis tells Charlotte off and rescues Rikki.
38	"Monster"	14 December 2007	212
When the girls are searching for a coral for Cleo's fish, Emma finds it, but she accidentally cuts herself in a coral. Emma starts eat fish food and acting weird. Cleo's fish is acting weird too. When Emma arrives to Marine Park to go swimming, a little girl sees her and tells that to her mum, but no one believes the girl. Cleo, Rikki and Lewis must bring Emma back home, but the problem is: Lewis has a date with Charlotte! While searching Lewis, Charlotte ends up bumping into Cleo and assumes Cleo is there to crash her and Lewis' date. After bringing Emma to home, Emma splashes herself in water, but as she turns into mermaid, the white scals appears. It's revealed the blame for white scales, eating fish food and acting weird is a coral!. Lewis brings Cleo's fish to Laurie and Laurie creates the antidote. The antidote cures Cleo's fish. Lewis brings more antidote to help Emma, but she escaped. Later that night when Emma's parents are having a romantic dinner, Emma steals the lobster and eats it. Cleo, Rikki and Lewis arrives and sees Emma as monster with white scals. Lewis splashes Emma with antidote and she returns to normal.
39	"Camping on Mako Island"	21 December 2007	213
The revived Sertori family camping holiday is ill-fated not just by choice of location, Mako Island, but in the unfortunate timing of coinciding with the full moon. Cleo's friends and Charlotte tag along to help one another stay out of trouble but Lewis' plans are soon tested when the girls decide to face the powers of the full moon. When Charlotte and Lewis decide to have a romantic walk, Lewis spots the girls and leaves Charlotte. Scared, Charlotte heads back to camp but bumps into Cleo, she torments Cleo because she thinks Cleo is jealous of her new relationship with Lewis. Angry, Rikki and Emma who are watching nearby strike Charlotte with lightning, scared Charlotte runs away and finds the moon pool but at the height of the full moon may have unforeseen consequences. The girls defeat the power of moon and Emma freezes the moon pool so Charlotte can't become a mermaid. Lewis arrives and brings Charlotte back to the camp.
40	"Cleo vs. Charlotte"	28 December 2007	214
After confiding in her that she misses spending time with Lewis, Cleo takes Rikki's advice to re-establish her friendship with him and to embrace her unique abilities, after all, unlike Charlotte, Cleo is not just an ordinary girl. Emma is disappointed to be passed over for a promotion at work but is even more upset by the identity of her new supervisor and all of his changes to the café.
41	"Irresistible"	4 January 2008	215
When he learns about myths considering ambergris, a substance which attracts mermaids, Zane seeks the help of Lewis. But Lewis thinks nothing of it and leaves the bottle of ambergris Zane bought on the Internet outside the Juicenet Cafe, where Nate finds it. Whenever the girls are around him they are strangely attracted to him. Will they come to their senses before it is too late?
42	"Visions"	11 January 2008	216
When Elliot asks Lewis for advice about girls, no one suspects who he plans to ask out on a date. Cleo and Lewis join the young couple on their first date to the water park and while it takes Elliot a bit longer to learn his lesson, the chaperones also come away a little wiser...and wetter. Cleo and Lewis realize that their friendship is strong and no relationship can stop that. Cleo gets splashed by water so she jumps into a show pool. Lewis has to help her protect her secret, which causes him to realize he still cares for Cleo. Emma gets the wrong idea about Rikki's secret meetings with Ash. Lewis is troubled by a reoccurring dream about Cleo being discovered as a mermaid.
43	"Moonstruck"	18 January 2008	217
The full moon comes around again. When Ash has trouble asking Emma out, he comes to surprise her. Meanwhile Cleo sees the moon and gets Rikki to see it as well. They lead Emma into the bathroom, where she sees the full moon too. Will Lewis arrive in time to save the mermaid secret?
44	"The Heat is On"	25 January 2008	218
Cleo throws a party for the girls' first anniversary as mermaids. But not all goes as planned when Ash and Zane have a fight, resulting in Emma and Rikki falling out. Cleo wonders whether she will have to celebrate by herself. But at the last minute, Emma and Rikki come after they have resolved their differences.
45	"The Gracie Code (Part One)"	1 February 2008	219
While looking research trying to uncover the secrets of the moon pool, Lewis uncovers the work of Max Hamilton, who fifty years earlier found himself in much the same role that Lewis is in now. To earn the old man's trust, Lewis risks betraying the girls' secret but the story Max has to tell will shed more light on the history of the moon pool and the girls' lockets.
46	"The Gracie Code (Part Two)"	8 February 2008	220
Charlotte wants answers as to why Lewis is spending so much of his time with Cleo and the girls. Charlotte appears to be satisfied with Cleo's vague excuse that Lewis is helping them with a project, but her curiosity is piqued when, amongst Max's research papers, she spots an old photo of Gracie... her grandmother. Lewis is tasked with finding out exactly what Charlotte knows about her grandmother, but while looking for her own answers, Charlotte makes a startling discovery. Ash makes a well-intentioned attempt to help Emma overcome her apparent fear of water.
47	"Then There Were Four"	15 February 2008	221
Charlotte's persistence in searching out her grandmother's murky past leads her to Max who confirms all of her suspicions. Further research leads her straight to the moon pool on Mako Island where secrets are revealed and another is born: Charlotte becomes the fourth mermaid. Lewis' relationship with Charlotte is put to the test by his inability to confide in her but Charlotte has no such reservations.
48	"Bubble Bubble Toil and Trouble"	22 February 2008	222
Against Rikki's better judgement, the girls agree to make Charlotte feel welcome as the newest member of the 'mermaid club'. Faced with the prospect of failing physical education in school due to avoiding water, the girls are quickly forced into working together with Charlotte when they find themselves together on the school's beach volleyball team. Charlotte learns there is more to being a mermaid than she thought. She discovers she has all three powers: She learns of her power to control water at the JuiceNet Cafe when she accidentally smashes a glass when trying to reach for it; She discovers she has Rikki's power as well when she puts her hands on her tail and realizes she can make it evaporate; While in the JuiceNet cafe again, Rikki asks how she got dry so fast and Charlotte shows her that she has the heating power as well before experimenting and realizing she can also freeze water.
49	"Reckless"	29 February 2008	223
Concerned about Charlotte's ability to use her new-found powers wisely, the girls offer to help her learn about her powers, but Charlotte refuses their help and becomes determined to prove herself as the only "true mermaid". She also reveals that she has a fear of dolphins. Lewis tries to help her, but he leaves to find Cleo, Ronnie the dolphin accidentally splashes Charlotte leaving her to dive into the water, with her fear she screams for help even when she is in mermaid form and almost boils Ronnie. Cleo and Lewis soon return causing Cleo to stand up to Charlotte and Charlotte realizing that Cleo is stronger than she thought. When Lewis runs afoul of Nate, his pacifist nature causes Charlotte to come to his defence. Can she be stopped before she goes too far and exposes the group's secret? Or even hurt Nate?
50	"Three's Company"	7 March 2008	224
Charlotte and the girls clash over the planning for Lewis' birthday. Tired of Charlotte's intrusion into what was once their close friendship group, Rikki excludes herself, promising Zane she'll spend more time with him instead. At Lewis' suprise party, Charlotte becomes jealous of Cleo and locks her and Emma in a pool closet telling Lewis that they left. Zane convinces Rikki to go to Lewis' party to show Charlotte that she hasn't won, she rescues Emma and Cleo and Lewis' and the girls hang out with all their friends from school, Emma, Cleo and Rikki also tell Charlotte they tried to make her feel welcome and don't wont to have anything to do with her.
51	"Sea Change"	14 March 2008	225
Her short-lived friendship with the other girls is over and Charlotte demands that out of loyalty to her, Lewis is to have no more contact with Rikki, Emma and, most of all, Cleo. Charlotte then steals Cleo's locket, telling Cleo that she is pathetic. Charllote tells Lewis that Cleo gave her the locket but Lewis becomes suspicious. Cleo leaves a message for Lewis but Charlotte steals his phone. Isolated and intimidated, Cleo runs away from home only to find herself in the company of sharks. Lewis then discovers his phone in Charlotte's bag and leaves with Emma and Rikki to find Cleo. Charlotte then catches up with Lewis demanding that he stops seeing the girls at all. Angry, Lewis tells Charlotte that he knows about what she did to Cleo and breaks up with her. But by choosing sides, a powerful enemy is created. Lewis rescues Cleo, his and Cleo's relationship is back and he takes Cleo back home. The episode ends with Charlotte upset and the in the mood for revenge.
52	"Finale"	21 March 2008	226
The girls try to warn Charlotte about the full moon but she doesn't listen. The full moon rises again, and Charlotte deliberately looks at it and it makes her obsessed with revenge and determined to be the only mermaid so as to make Lewis care about her more. Meanwhile, the girls are at Emma's, trying to stay away from the moon, but then Charlotte comes near the house and starts "playing" with the water in Emma's house, just as Ash comes to visit Emma. Lewis convinces Charlotte to stop, and they go to Mako Island together. Cleo is worried about Lewis and follows them. Charlotte was waiting for her, because she realizes what Lewis hasn't told her: that if there was any mermaid in the moon pool at the time the moon was passing over it, that mermaid would lose her powers forever! Emma and Rikki arrive in time to save Cleo. They fight with Charlotte and, after falling into the moon pool, she loses her powers permanently. Charlotte goes to visit Lewis fishing, but he is still upset with her. She tries to convince him to return her but he isn't interested, he asks for Cleo's locket back and gives it back to Cleo. Emma finally reveals to Ash that she is a mermaid. Ash reacts well to the news, and the season ends with Lewis, Zane, and Ash watching the girls run into the ocean and turning into mermaids.

Series three: 2009

Lewis moves away and Rikki, Cleo, and Emma are left alone. Miriam is still at her ways, but she is left on Mako Island by herself after a pair of boys leave her there as a joke. She falls in the same hole that Rikki, Cleo, and Emma fell through and discovers the Moon Pool. She becomes a mermaid and almost exposes the secret while swimming in the ocean. She gets caught in a fishing boat's net and Rikki, Cleo, and Emma have to save her.

Television films

Title	Original airdate
"H2O: Just Add Water: The Movie"	June 8, 2007
This TV movie summarised the events of the beginning of series one, using clips from the episodes "Metamorphosis", "Pool Party", "Catch of the Day", "Party Girls", "Lovesick", "The Denman Affair" and "The Siren Effect".

External links

• Episode guide at the Internet Movie Database
• Episode guide at TV.com