St. Canard is experiencing a major heat wave and Drake tries to install a sprinkler system with funny results. It seems that Drake is missing a part and he goes inside to ask Launchpad about it. Launchpad is watching television and the program is about bad tasting water. It seems that a lot of water companies in town have terrible tasting water except Bud Flud's water. The reporter says that it seems that someone has been tampering with the water and Drake decides to investigate as Darkwing Duck.
Darkwing and Launchpad stop to get something to drink and find that there are only two companies that have not been affected. They stake out one and find Bud Flud tampering with the water. Darkwing confronts Bud and Bud falls into the vat of water he just polluted. Darkwing rushes to save him, but it's too late and Darkwing thinks that Bud is no more.
A magazine reporter approaches Herb Muddlefoot and asks if he can photograph his sprinkler system. Drake is jealous and tries to turn on his system and winds up flooding the house. He is told that he needs a 3/4 Pinckney flange and he goes off in search of one as Darkwing Duck.
As he and Launchpad are driving around searching for the part, Darkwing is grabbed off the motorcycle by a giant hand made of water and dragged down into the sewer. Darkwing is approached by a strange character in a long raincoat and hat disguising who he is. Darkwing learns that this mysterious figure was once Bud Flud and is now The Liquidator and he is made completely of liquids. Darkwing tries to punch him but his hand only goes through him. Liquidator changes form and throws Darkwing against the wall. Liquidator then surrounds Darkwing with walls of boiling water. Just then Launchpad comes in and hits Liquidator with the door. This causes Liquidator to lose his form and Darkwing is freed from the boiling walls of water. They chase Liquidator to the St. Canard Water Works where Darkwing uses his newfound plumbing skills to block every attempt by Liquidator to escape the pipes. He, however, misses one pipe and Liquidator escapes and pounds Darkwing in the head. Darkwing mentions how hard it is to stop water from leaking and gives Liquidator an idea. He turns all the water hard. He forms a giant hard water ball and uses it against Darkwing and Launchpad. They crash through the building wall and into the bay where the water is normal. Liquidator quickly changes it into hard water too and traps Darkwing and Launchpad. Liquidator tells them that he is going to sell his water for $5,000 a bottle since it's the only drinkable water in town.
Darkwing and Launchpad are cut free, for a fee, and they go to a tall building and jump off to break the hard water block around their feet. They break free, though painfully, and go to Liquidators bottling factory.
Darkwing has a plan and he bursts in on Liquidator with a giant sponge making Liquidator retreat down the drain. He is forced into a water heater and Launchpad turns up the heat. The liquidator escapes once again in the form of steam. Launchpad points out that the heater is building pressure and it explodes. Liquidator retreats into a room and accidentally walks into a freezer. Darkwing and Launchpad think they finally have him when all of a sudden the water bottles in the room start to pop open and small water creatures come out and set Liquidator free. Darkwing smashes the partially frozen Liquidator and threatens to turn him into snow cones unless he turns the hard water back into normal water. Liquidator does it and water starts to flood the room and Liquidator is once again free. Darkwing and Launchpad dive into the sewer to escape the flood of water. They find a part that Darkwing had lost for his sprinkler system and know where they are.
Darkwing and Launchpad pop up from the sewer and try to stop the liquidator from getting to the surface to no avail. Gosalyn is glad to see the water until Liquidator appears with his little minions. He tells his minions to capture her. Darkwing sees some cement bags and gets an idea. He pours out the bag on Liquidator and turns him into a concrete statue. All the water now turns back to normal.
Drake is approached by a reporter to take pictures of his water system witch now features the Liquidator statue as the centerpiece.