What do you mean, "that needs an adapter" it is 1/2" and I am connecting to 1/2"? I am amazed when I looked at how many different threads and pipe types there are, I grew up knowing/learning this stuff. Plumbing is more confusing than Funeral , Wedding, Graduation and other ceremonial things, (all of which confuse me). First let me defend my vocation, many excuses exist for this confusing esoteric stuff.
I will begin by saying things develop, names need to as a result, then ways are needed to prevent some pipes from getting connected to other pipes. Let me jump to the point, Threaded pipe is screwed together and uses a tapered thread to cause a tight seal. Thermal Plastic pipe such as PVC,ABS,CPVC are all joined using a solvent that heats the pipe as it cures. PVC Glue is a misnomer. I am working on a video that will expose all this esoteric nomenclature including all these weird threads and 5/16 and 7/8 threads as well as CTS, IPS, NPT, Tube VS Pipe, hose VS tube, pressure VS non pressure, metallic VS nonmetallic, Gas VS Water, waste VS Potable, Exterior VS interior only, old VS new, good VS bad, So stay tuned for the rest of the story