What Is the Shower Curtain Effect and How To Stop It

I was a boy when Alfred Hitchcock’s 1960 horror classic Psycho hit the theaters. Had I been a precocious lad and keener on physics watching the scene where Janet Leigh’s character is attacked while taking a shower, I would have stood up in the theatre and shouted, “The scene is fake! Look, there’s no shower curtain effect!”

Indeed, the shower curtain did not move inward as it should have. It didn’t creepily cling to Ms. Leigh when water fell from the showerhead. The curtain stayed put until Anthony Perkins’s character swiped it aside so he could wield his knife.

No one needs drama in the shower, so here’s an explanation of the dreaded shower curtain effect and how to stop it.

What Is the Shower Curtain Effect?

This phenomenon happens after you turn on the shower. As you stand there, the shower curtain drifts toward you, sometimes sticking to you.

If you like trivia, you’ll be tickled to know the shower curtain effect can also be called Bernoulli’s Principle. In his 1738 book Hydrodynamica, Swiss mathematician Daniel Bernoulli wrote pressure decreases when airflow increases. The shower’s spray increases airflow, reducing pressure in the showering area and causing the curtain to blow in.

What Causes the Shower Curtain Effect?

There are three explanations for the shower curtain effect, all based on the difference in air pressure in the showering area versus the non-showering area.

Air density difference

Warm water from the showerhead causes warm air, which rises to the top of the shower and spills over the shower curtain rod. This reduces air pressure inside the lower part of the showering area. Outside air, at a higher pressure, moves toward the low-pressure region at the bottom of the curtain, pushing the curtain with it. This makes sense when water is warm, but the shower curtain effect also occurs with cold water.

Bernoulli’s Principle

Since increasing velocity results in decreasing pressure, that showerhead spray pushes air across the inside surface of the curtain. This increases air velocity and decreases air pressure inside the curtain. The pressure differential between inside and outside causes the curtain to move inward.

Interestingly, Bernoulli’s Principle also helps explain why an aircraft achieves lift. Its wings are curved so air flows faster over the top, lowering air pressure, and flows slower underneath, which raises air pressure!

Horizontal vortex

Shower spray makes a horizontal vortex, a mass of fluid that revolves around a center axis line. A tornado is an example of a vortex. The eye of the vortex is a low-pressure region, which explains why objects and people can get sucked into a tornado.

In the shower, the axis of the vortex created by the spraying water runs perpendicular to the curtain. The low pressure of the vortex eye draws the shower curtain in.

8 Ways to Overcome the Shower Curtain Effect

Don’t shower

You can enjoy a relaxing bath to clean up and calm down. No shower = no shower curtain effect.

Switch to a heavier curtain

The suction pressure of the shower vortex is often too weak to move heavier curtains. Or, instead of closing the curtain altogether, leave a little gap on one side.

Use a curtain with suction cups or magnets

Some shower curtains have suction cups on the bottom edge, which you push onto the sides of the shower. Other curtains come with magnets at the bottom, although these are not effective on acrylic or fiberglass tubs.

Replace the showerhead

Install a showerhead that doesn’t atomize water as much. Gentler water spray decreases air speed inside the shower.

Install a shower door

The shower curtain effect really bothers you, install a glass shower door. Or create a wet room bathroom with no shower curtains or doors.

Install a low curtain rod

Use a telescopic shower curtain rod to block the curtain on its lower part, preventing it from sucking inside.

Use a weight and a string

Attach a weight to a long string and tie it to the curtain rod in the middle and on the inside of the curtain. The weight low against the curtain and above the rim of the shower pan or tub stops billowing without letting the weight hit the pan or tub and damage it.

Use a curved shower curtain rod

A curved shower curtain rod increases showering space and deceases the pressure difference between the inside and outside. Also, a curved rod holds the curtain against the inside wall of a tub, especially if you use suction cups or magnets at the bottom.

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