Avoiding the Shower Curtain


It’s been 3½ years since I had a shower curtain; I’ve always had an apartment with a bathtub door. Our new place has no doors, so we’re back to curtains. We have a lightweight fabric shower liner that we use instead of the normal vinyl curtains; it means we can just throw it in the washer every so often and not worry about mildew buildup. The problem is that the light weight means it is particularly susceptible to the annoying “shower curtain effect” (the phenomenon where the shower curtain billows inwards when the shower spray is running).

There are two widely accepted causes of this “shower curtain effect”:

  • Hot shower water heats the air, which then rises. Cold air rushes in via path of least resistance to take its place. This path of least resistance is typically under the bottom of the curtain, leading to inward billowing. This is not the only factor, because it has been shown that cold-water shower spray still exhibits the shower-curtain effect (albeit a reduced effect).
  • The shower spray has some kind of thermodynamic effect that generates a force normal to the direction of spray, which happens to be inwards of the shower curtain.

Armed with this knowledge, there are a few tried-and-true solutions:

  • Replace the curtain with a glass door. I’m a renter; this option is not available to me.
  • Install magnets or weights at the bottom of the curtain. Most curtains come with magnets sewn into the bottom corners, or with sand sewn into the bottom hems of the curtain. Magnets only work if the tub is metal (ours isn’t). Weights don’t seem to work that well, or at least the weights in our liner aren’t sufficiently heavy to prevent the shower curtain effect.
  • Don’t draw the curtain all the way closed; leave more room at the side for the cold air to enter. This actually works, is reversible (no security-deposit-affecting modifications to the bathroom are required), and is cheap (no purchase required). The downside is that cold air is entering via the side, nullifying most of the motivation for a hot-water shower.
  • Add an outer curtain. Froofy shower curtain/liner sets are available at upscale housewares establishments like Target. The outer curtain typically hangs low to the ground (maybe slightly lower than the inner liner), and serves to block air, as well as to provide some aesthetics to the bathroom decor. The inner liner serves to keep the water from getting out. This has the reversibility and cheapness properties of the preceding solution, without the disadvantage of cold-air entry.

We had an extra vinyl curtain (new) that the landlord had left for us; I just installed that on the outside as an outside curtain, while using our nice lightweight fabric liner on the inside as a liner. Voilà: no more shower-curtain effect.

  1. #1 by David S on Thu Nov 22, 2007 - 7:35 pm

    Most of the problem is due to Bernoulli’s Principle which says that “for an ideal fluid (low speed air is a good approximation), an increase in velocity occurs simultaneously with a decrease in pressure”. This is the same principle which gives lift to airplane wings. In a shower, the water spray drags the air along with it. The increase in the air’s velocity causes a reduction in the pressure inside your shower. The outside air which is not moving is at a slightly higher pressure and pushes the curtain inward. Bernoulli’s equation which quantifies the effect states that the pressure change is related to the velocity squared. In other words if you double the velocity the problem gets 4 times worse. Happily if you halve the velocity the problem will be only 1/4 as bad.

    The original spray head on my shower had only a few very small holes, so in order to get enough water the velocity had to be very high and as a result the curtained billowed in so far that it could not stop water from splashing all over the floor. I switched to a shower head with more and larger holes. That made a big difference. I can still get as much water as before but it is flowing slower so the problem is reduced to an acceptable level. You have to throttle back on the faucet a bit to avoid billowing but that’s not bad.

  2. #2 by Shower trays UK on Tue Feb 19, 2008 - 4:30 am

    I’m more of a fan of a door myself, but still think your shower curtain tips are very useful for anyone having one..

  3. #3 by kitchen on Tue Feb 19, 2008 - 4:29 pm

    To create less turbulance in the air you can fit an old fashioned showerhead where the volume of water is greater without having to increase the velocity of the water coming out.

  4. #4 by Julie Anderson on Mon Mar 3, 2008 - 4:45 am

    I am currently searching for weights to sew into the shower curtains we are making does anyone have any suggestions? Preferably purchased in the UK.

  5. #5 by David S on Mon Mar 3, 2008 - 9:57 am

    If you attach weights they will have to be heavy. I tried attaching half a dozen 5/16″ dia x 2″ long bolts. But they had no effect. You might try using large diameter steel washers. They aren’t too expensive and you could buy them at any hardware store. They need to be plated to avoid rusting.

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