I'm new to homebrewing, and I've recently encountered a problem with an s-shaped airlock. I clean it out with water after use, but it takes forever to dry on its own. This time, it's started growing mold inside after washing it out. Is there some way to dry out the airlock to prevent this sort of mold growth? I imagine if I cleaned it out with vodka or something similar, it would prevent such growth, but I'd prefer to clean with water, because it's essentially free.
Couple of things if you plan to keep using these air locks it's fine to rinse everything with water but run sanitizer through it. I keep sanitizer on hand in a spray bottle for all sorts of things. Try spraying a generous amount in the air lock after rincing gunk out of them. It might not be "free" but throwing out a bad batch because of an infestation is way more expensive.
If however you can see any gunk in there you need to get it out of the airlock before storing and you'll need to use a cleaner. I like oxyclean because it's cheap and works well. Fill a small container and emerge the lock in there.
A second suggestion would be to switch to a blow off tube or 3 piece airlock as IMO they are easier to clean as their are no s traps for crud to be trapped in. I prefer the s shaped locks for secondaries only.
It's ill-advised to take any shortcuts with cleaning or sanitation, even with an airlock. Clean it with PBW (powdered brewery wash) or OxiClean solutions prepared according to the directions on either package; alternatively, use un-scented chlorine bleach. Whatever is used, soak for a couple hours, and rinse thoroughly with clean water.