Does every sink need a P-trap?

“Just moved into a house. Previous owner DIYed the all over the place, but rarely did a good job or even finished the job. This drain is very smelly and lots of pink bio film, so I need to at least clean out the trap, but probably easier to replace.”source ↗

“I've lurked here for a while but never braved any sort of plumbing job before, but I'm ready to give this one a try if necessary. This bathroom sink has drained slower and slower over the last year or two.”source ↗

“this is waste pipe..on previous dishwasher it was air tight controlled.. this just looks and probably smells like an open waste pipe....is this okay or should I be complaining?”source ↗

“I’m finishing my basement and am wondering how to plumb a vanity drain. The house was built with shower and toilet rough ins already in place, but nothing for the vanity drain.”source ↗

“I'm wanting to replace it with a utility sink, so how would I do that the right way?”source ↗

“Hello! I am trying, for the first time, to learn how to connect a sink.”source ↗

“I attached the accordion adapter but it leaks at the p-trap connection (or lack there-of....). I have a rubber gasket in there that does not seem well fitted.”source ↗

“I replaced a kitchen drain. The old drain was connected to a pipe with no lip and just a silicone gasket. It had been that way since I bought the house, so at least ten years. But now I can't reconnect the drain without the pipe slipping off. Is there a way to connect this without replacing the pipe?”source ↗

“About to install a new vanity but I just noticed that the drain to the sink doesn't have a P or S trap. Does every sink need one?”source ↗

“Had a sink that had to be reinstalled recently, and I figured with the plumbing already help might as well redo it correctly. What parts do I need and or need to change?”source ↗

“On the exposed end of the elbow, the threading is galled and bent out of shape.”source ↗

“I'm not the one who put this in. Looking for advice on how to replace it.”source ↗

“Our original plumbers did a bunch of things slightly wrong, and our sink was slightly off center. We replaced the stone top and sink and now it's properly centered and the arm going into the wall and vertical stack is now around a quarter to half inch too short to reach the trap. Length wise not height.”source ↗

“Unfortunately the part between the 90 and the 60 going into the wall is so short that if I cut it, there's not enough pipe to fit a new 90 over.”source ↗

“What can I do? I don't see where I can cut this or what kind of adapter I can use to rebuild this trap. Anyone have any ideas? Is there some kind of adapter I could use because I'm not seeing a spot I can cut this to fit a coupler and new 90 to.”source ↗

“We are replacing a vanity at home, and the new sink does not have an overflow on it.”source ↗

“Only problem is there is no return portion on the sink for that. So basically water is able to pool between the top gasket and bottom gasket on the skink, and leak out of them.”source ↗

“this came in the kit and i'd like to avoid dropping another hundred bucks and tossing a brand new drain into the "Maybe one day this will come in handy" plumbing box in the back of my basement.”source ↗

“A friend came over today and said that was a vent, and that the floor would probably have to be opened up for the vanity drain.”source ↗

“I don’t know how to hook up this sink? The black ac line(i believe) seems to be in the way for me to install a standard flex hose.”source ↗

“For some reason, it won't tighten up (keeps spinning) with the gasket between the tub and the waste pipe.”source ↗

“With the gasket in place, it tightens and then become loose when I try to make it tight enough.”source ↗

“I can't get underneath the tub, and if I leave the gasket in place without the drain shoe being tight enough, water leaks onto the floor below.”source ↗

“It catches the pipe fine but just won't stay tight with the gasket in place.”source ↗