A trope of science fiction, if aliens (or humans in the future) bathe at all, you can bet that they will use something completely different from soap and water. This is usually not because of any Bizarre Alien Biology, but rather just something to show more advanced technology and/or how different the aliens or future humans are. It can also, depending on how sensitive the Moral Guardians are being, have the secondary advantage of letting characters have a shower without showing skin.
Note that this can be Fridge Logic when you realize that since water is recycled on spaceships and stations, there is no reason they can't spend the additional energy and equipment to have as much pure water as they want. If they don't clean the dirty water (and urine, etc.), they still have to store it (or throw it into space). It makes more sense to clean it and reuse it. Humans actually "make" water (oxygen plus glucose equals carbon dioxide and water). Although if you do allow water showers you probably have to provide more water storage space. Of course, depending on the level of technology (or how grimy your setting is), you can justify this by having the recycling process be time consuming compare to how quickly you would use the water by washing everything with it.
- In Transmetropolitan, it takes less than a second for a "Voice-Keyed Physical Cleaning Unit" to turn Spider Jerusalem from hairy mountainman into a full-body Bald of Awesome. Given that he Screams Like a Little Girl while it emits a blinding flash of light, it apparently does so with lasers. It also appears to have been permanent, as he is never again shown with a single strand of hair anywhere on his body. Not as crazy as it sounds — Laser hair removal was developed in The '90s.
- Robert A. Heinlein's article "Where To" mentions a futuristic shower which not only pours water on you but can also do the following: "warm air drying, a short massage, spraying with scent, and dusting with powder". He mentions "freshers" (AKA "refreshers") similar to this one in several of his other stories, including "Coventry", "Methuselah's Children", Farmer in the Sky, Friday, The Cat Who Walks Through Walls, The Number of the Beast and Time Enough for Love.
- In Priest-Kings of Gor Cabot is in the realm of the Priest-Kings (the gods of the planet) and like all humans is required to shower several times a day because the Priest-Kings are Terrified of (Human) Germs. One time he fills his water bowl from the shower and discovers that that ain't water!
I had naturally supposed the fluid to be simply water which it closely resembled in appearance, and once had tried to fill my bowl for the morning meal there, rather than ladling the water out of the water pan. Choking, my mouth burning, I spat it out in the booth."It is fortunate," said Misk, "that you did not swallow it for the washing fluid contains a cleansing additive that is highly toxic to human physiology."
- In the Star Wars Expanded Universe novel Shatterpoint, Mace Windu gets a water shower upon arrival at the local space port, but also goes through a pro-biotic spray. On that specific planet, ships take off and land in a weak energy field that kills microscopic life-forms to counter-act a ubiquitous airborne metal-eating fungus. The spray (as well as a couple of orally-taken tablets) replace the beneficial bacteria most living creatures have on their skins and in their digestive systems.
- In Wicked, Elphaba sidesteps her water allergy by cleaning herself with mineral oil, poured over herself from a jug and then carefully scraped off.
- In the Vorkosigan Saga sonic showers, toothbrushes, and other cleaning devices are frequently mentioned. Though they're not as good as "real" showers — in Memory, Ekaterin comments that you can't clean a baby's bottom in one!
- In Gunner Cade by Cyril M. Kornbluth and Judith Merril, the entire barracks is a shower, and one soldier who is Not a Morning Person barely gets his bedding shoved in his locker before the water vents open up.
- Star Trek: The Next Generation and the series that follow it chronologically usually the Federation using sonic showers.
- While generally playing this trope straight, bathtubs do crop up from time to time aboard the Enterprise-D+, usually Deanna Troi is involved.
- Star Trek: Voyager averted this in the pilot episode, with Neelix taking a soap and water bath (though there was a plot reason — to shown the abundance of water Voyager had). Janeway also has a bath in her quarters as a Captain's privilege. Later it was subverted with an alien race whose strict rules call for purified water to be used. Fridge Logic ensues once you realize just how bad water is at cleaning if the contaminants don't happen to be water-soluble or are dangerous microorganisms. The rest of the time it was played straight with sonic showers. One is eventually shown on-screen being used by B'Elanna Torres (though for some reason it has a Video Phone inside. Maybe Starfleet was hoping more hot robot babes would turn up in them?)
- Star Trek: Enterprise shows that 22nd century Earth ships still have conventional showers. This is actually serving the Rule of Cool in one scene, in which the artificial gravity fails just while Captain Archer is taking a shower, and all the water drops start hovering in the air.
- Babylon 5
- Water conservation is important on the station so only the executive suites and command quarters get showers with running water; everybody else has to make do with "vibe showers".note
- Earth's space ships don't have water showers even in the command quarters; when Captain Sheridan was transferred to Babylon 5, he was seriously happy when he learned his quarters included "a real live honest-to-god shower with running water".
- The Minbari use a chemical that removes the outermost layer of skin; it symbolizes rebirth, at least to the Religious Caste. As you'd imagine, it does absolutely horrific things to hair, as Delenn discovers when she becomes a Half-Human Hybrid (as an ordinary Minbari, of course, she had no problem with this, since the Minbari have little or no hair). She ends up calling on Ivanova to teach her about hair curlers — and later, "odd cramps."
- Stargate Universe had a sort of mist shower onboard the Destiny.
- The Girl from Tomorrow has a "shower" in the year 3000 that consists of a band of light running up the body. It even removes 20th-century permanent hair dye because it is recognised as dirt.
- Most showers aboard the seaQuest DSV are of the ionic kind (whatever that means). When a woman from the past appears and tries to take a shower aboard the sub, she turns it on. When no water comes out, she cranks up the dial, only for the woman in the next stall to come in and crank it back down, telling her to leave some ions for the rest of them. Apparently, officers can use water showers, but they're rationed. The woman lets the newcomer use one of her shower rations. The strange thing is, they're underwater, which means they should be able to get fresh water through desalination. Then again, with hundreds of crewmembers, it would probably be too much for any system, hence the rations.
- Big Head Press regularly has "Clean-branes" appear in its sci-fi comics such as Timepeeper and Quantum Vibe — membranes of memory plastic that one simply steps through to strip all detritus from one's body, leaving the user not only clean as a whistle but bone-dry. In some cases it's implied to even work through and on clothes.
- Current spaceships and stations either offer no bathing (for ships) or limited bathing (stations).
- The International Space Station (ISS) does not feature a shower, although it was planned as part of the now cancelled Habitation Module. Instead, crewmembers wash using a water jet and wet wipes, with soap dispensed from a toothpaste tube-like container. Water is recycled on the ISS, the system collects, processes, and stores waste and water produced and used by the crew — a process that recycles fluid from the sink, toilet, and condensation from the air.
- However, ISS's predecessor Skylab did feature a shower. It consisted of tube-shaped container where water sprayed from the top and was pulled towards the bottom for collection by exhaust fans. Showers were strictly limited due to limited storage and processing capacity.
- By Islamic tradition, clean sand or dust may be used as a cleanser for ritual ablutions (tayammum) if pure water is unavailable, or if there's a valid medical reason why the person cannot wash with water.
- Dust bathing is a typical self-grooming behavior for many birds and some mammals.