It is the most counter-intuitive failure in the bathroom: you turn the head a little more to stop the drip, and the drip gets worse. Nothing is stripped. The gasket is being crushed, and every extra turn pushes it further out of its seat.
The seal is the gasket, not the threads
A shower head connects to a 1/2-inch shower arm. On most heads the joint is sealed by a flat or conical rubber gasket that sits inside the collar and compresses against the end of the arm. The threads do one job: they pull the two surfaces together. They do not seal anything.
This is why thread tape is often counter-productive here. Tape is for tapered metal-to-metal joints, where the threads themselves are the sealing surface. Adding tape to a gasket joint changes the distance the collar can travel, so the gasket is compressed less or unevenly — and the leak continues.
What over-tightening does
A rubber gasket is roughly incompressible. It seals by deforming elastically into the microscopic gaps between two surfaces. Give it the right amount of compression and it fills the gap perfectly. Give it too much and it has nowhere to go: it extrudes sideways, folds over its own edge, or gets pushed out of the recess entirely.
Once it folds, the seal is broken along the fold line, and the leak is worse than before. Turning harder compresses the fold tighter and pushes more rubber out. That is the whole mechanism behind "the more I tighten it, the more it leaks".
"Put them on hand tight and that's it. I'm certain you are over-tightening it."
Find the actual leak point
Dry the joint completely with a towel, run the shower for twenty seconds, and watch where the first bead forms. The location tells you what failed:
| Where it appears | Likely cause | Fix |
|---|---|---|
| Between collar and head body | Cracked collar or failed internal seal | Replace the head |
| Between collar and arm | Gasket deformed, missing or dirty | New gasket, hand-tight |
| Running down the arm from the wall | Arm-to-wall joint, not the head | Plumber or arm re-seal |
| Under the faceplate only | Faceplate seal or cracked body | Replace faceplate or head |
If the water appears at the wall end of the arm, stop. That joint is inside the wall plate, and a leak there can travel along the pipe. Shut the water off and get it looked at.
The correct install
- Clean both faces. Old gasket residue, grit and dried sealant all prevent the new gasket seating. A fingernail and a cloth are enough.
- Check the gasket orientation. Flat gaskets go flat side to the arm; conical ones go narrow end first. Fitting one backwards is a common cause of a persistent drip.
- Thread on by hand until the gasket touches the arm. It should turn freely. If it binds immediately, the threads are crossed — back it off and start again.
- Hand-tight, then a quarter turn. Half a turn at most with a wrench. If it still drips at that point, the gasket is the problem, not the torque.
- Test, then stop. Run the shower, dry the joint, and check after a minute. Do not "just give it a bit more" if it is dry.
If you needed a wrench to get it that tight, it is too tight. A shower head should come off by hand next time you need to clean the screen.
When tape helps, and when it hurts
PTFE tape belongs on tapered pipe threads: the shower arm into the wall fitting, for example. Two to three wraps clockwise, applied to the male thread, is right. It does not belong between a gasket and its seat, and using both is a reliable way to create a leak you did not have.
If the arm has a damaged thread and a gasket will not seal, tape can be a temporary measure — but the proper fix is to dress or replace the arm, not to keep adding wraps.
Cracked collar and crossed threads
Plastic collars crack when they are over-tightened once too often, usually along the moulding seam. A hairline crack opens under pressure and drips only when the shower is running, which makes it easy to misdiagnose as a gasket problem. Look closely with a torch before you buy another gasket.
Crossed threads feel different: the head goes on at an angle and will not seat flush. Forcing it damages both the collar and the arm. Back it off completely, inspect the first thread on each, and restart. If the arm thread is flattened, replace the arm.
Prevention
Keep two spare gaskets in the bathroom drawer. They cost less than a coffee, they harden with heat and age, and replacing one takes two minutes. When you clean the screen — which should be monthly — look at the gasket at the same time. A gasket that has gone flat and hard will not seal no matter how carefully you tighten it.
Written and reviewed by the Flow Restore editorial team. Community quotations are summarised and attributed to the thread they came from; they are not endorsements. Nothing here is a substitute for a licensed plumber's assessment.