The time after which "adult" content can be shown. This is usually defined as programs with [[BloodierAndGorier intense violence]], [[ClusterFBomb coarse language]], [[NudityTropes naughty bits]], [[SexTropes sexuality]], [[StuffBlowingUp lots of explosions]], [[ArsonMurderAndJaywalking and]] [[DiesWideOpen characters who die with their eyes open]].

The watershed varies from country to country. It's typically around 9:00 pm (as in the U.S., U.K., Canada, and Australia), but it can be as late as 10 pm (as in Germany). Japan has laxer standards in general, but its concept of OtakuOClock starts as late as 11 pm or midnight. In many regions, though, the watershed is in the middle of UsefulNotes/PrimeTime viewing; everything before the watershed is "family programming", whereas the shows afterwards are the more "adult" hit shows. This means that the fact that a show airs after the watershed doesn't mean that a lot of people won't be watching it.

The concept was largely popularized by the U.K., which uses the specific term to regulate TV content. (Interestingly, British radio doesn't have a watershed, just a list of prohibited bad words.) In the U.S., the related concept of UsefulNotes/SafeHarbor refers to a policy of the Federal Communications Commission; it's the time period in which the FCC won't go after you for airing "adult" programming (as long as it's not legally obscene).

As an aside, the term "watershed" comes from agriculture; it refers to an earthen barrier that prevents irrigation water from crossing into a neighboring field, allowing the two fields to run on different watering schedules (and thus house different crops). It's also applied on the larger scale of rivers with a watershed being an imaginary line separating the water that flows into one direction from that which flows into another as in the Continental Divide which separates rivers draining into the Atlantic from those draining into the Pacific.
(The above definitions also gave rise to the phrase "watershed moment," which refers to any event that separates two historical periods. This has nothing to do with broadcasting.)
!!General Examples:
* Japan brings us OtakuOClock, a time period starting at around 11 pm and extending into the early morning in which the ''really'' risqué shows can be aired. These include anime series based on [[HGame H-Games]] (albeit cleaned up for TV) and live-action dramas with more extreme content. Examples include a live action adaptation of the adult manga/anime ''Hen'' (known as ''Strange Love'' in the US), which had a scene of the two {{Schoolgirl Lesbians}} skinny dipping and making out in the school pool; and ''Invisible Girl Ea'', revolving around a young woman who spends the entire series as an InvisibleStreaker.
* North America has a few quirks with its watershed programming:
** The watershed time in the U.S. and Canada can get tricky because they span many time zones. If you get the East Coast feed in Hawaii, the watershed can start as early as 3:00 pm, and the really adult stuff can start at 6 or 7 pm. The West Coast feed is better by a few hours.
** The U.S. watershed doesn't seem to make much of a difference in content on network TV; writers are hesitant to use bad language on either side of the watershed. And the MoralGuardians are in full force, too; when ''Series/NYPDBlue'' showed a glimpse of male backside, it caused quite an uproar despite this being post-watershed. The real distinction lies between the networks and cable; channels like Creator/{{HBO}} in particular are known to be much more relaxed in terms of content regulation.
** Canada's state-run broadcaster, the Creator/{{CBC}}, does not participate in the private networks' self-regulating MediaWatchdog group. As such, they've been known to air some pretty bad language on the six o'clock news (you know, as long as it's relevant). That said, they're not out of the reach of the national MoralGuardians.
** Sometimes programming is long enough to span both the pre- and post-watershed periods, and only the bit before the watershed will be censored. For instance, Creator/{{CTV}} showed ''Film/ErinBrockovich'' this way, and it got to air a triumphant "[[PrecisionFStrike Fuck you!]]" right after the first post-watershed commercial break.
* The British watershed is not meant to be an absolute dividing line; in theory the watershed is at 9 pm, but in practice it's as late as 9:30 to give the more sensitive viewers time to clear out. Similarly, films [[UsefulNotes/MediaClassifications rated 15]] will start airing earlier than films rated 18. Tamer shows and films might start airing at 8:30 on the reasoning that most of the film would be after the watershed. Creator/{{ITV}} in particular liked to needle the MoralGuardians by starting their dramas at 8:30 and avoiding violence, swearing, and nudity for the first half-hour -- after which all bets were off.
* In UsefulNotes/TheNetherlands, the watershed starts at 10 pm; no content with a 16 rating may be aired before that time. But after the Dutch watershed, anything goes, even hardcore pornography. The porn classic ''Deep Throat'' was even aired on a publicly-funded network after the watershed.
* The Latin American watershed is typically 10 pm; after that, the networks like to start airing [[SoapOpera telenovelas]] that are ''considerably'' HotterAndSexier (and often DarkerAndEdgier).
* The Australian watershed can vary, but the absolute limit is 10 pm. After that, networks can show movies and shows completely uncensored, even if they would otherwise get an MA or R rating. Advertising will also get HotterAndSexier as it gets closer to midnight.

!!Specific Examples:
* The British police drama ''Series/TheBill'' is an interesting case study. It started out in 1984 as a post-watershed series, meaning that it had liberal cases of sex, violence, and nudity. Then in 1988, the [[ExecutiveMeddling production team decided]] to move it before the watershed, meaning that everything was toned down and the show as a whole was LighterAndSofter. It ran in this slot for most of its life, before the executives decided to move it ''back'' to 9 pm in 2009.
* ''Series/DoctorWho'' airs before the watershed, but pushes the envelope to see what it can get away with in that timeslot. It airs on Saturday evening in a primetime slot, and it's gotten away with an infamously high body count, graphic violence, male-on-male and female-on-female kissing, bondage scenes, [[NightmareFuel/DoctorWho Davros' shirtless scene]], and [[ArsonMurderAndJaywalking characters dying with their eyes open]].
* Some ''Series/TopGear'' specials would air after the watershed, and the presenters would be aware of it. For instance, in the "''Top Gear'' Ground Force" special, an annoyed James May stopped to verify that the special would be aired post-watershed before dropping a PrecisionFStrike. (Well, he tried before [[CurseCutShort a hard cut to Richard Hammond]].)
* ''Series/TheLateLateShow'' was known to [[LampshadeHanging hang a lampshade]] on the phenomenon, especially when Craig Ferguson does a lot of swearing, even though it would be censored anyway. The censors did, however, allow RobotBuddy Geoff Peterson to get away with a hand gesture resembling masturbation because he didn't have genitalia.
* One of the most notable breaches of the watershed in Britain was the infamous [[SmarmyHost Bill Grundy]] interview with the SexPistols in 1976. Grundy provoked them into saying [[ClusterFBomb all sorts of swear words]] during prime time viewing hours.
* ''Series/EverybodyLovesRaymond'' ran into some weird watershed-related censorship on British TV. It aired on Creator/ChannelFour, which wanted to re-air the episodes the next morning for people who missed them, and as such decided to use pre-watershed censorship standards on a post-watershed show. In particular, Channel Four refused to air two Season Six episodes, "Marie's Statue" (suggestive artwork) and "No Roll!" (Ray and Debra's sex life), in spite of the fact that these episodes air with no problems in the notoriously prudish U.S.
* NickJr's "Nick Mom" lineup, geared towards the moms of their usual audience, had a problem with their West Coast feeds. People there were seeing (for example) StandUpComedy routines about sex, periods, vaginas, and all that fun about 6:30 or 7 PM ''their'' time. (See the East Coast West Coast feed problem mentioned above.) This caused controversy, and the channel responded by dialing it back a notch...which caused an even greater decline in viewership. Ultimately, the "Nick Mom" block was discontinued.