If you have a loose valve handle—on a shower, bathroom or kitchen faucet—tighten the screw that holds the handle in place. With some faucets, you'll have to pry off the metal button at the center of the handle. With others, you'll find a setscrew near the base of the handle. Setscrews usually require a hex (or “Allen”) wrench. If tightening doesn't work, the stem inside the handle may be worn, especially if it's plastic. Here's a trick to tighten worn stems on most types of faucets: Wrap the stem tightly with Teflon pipe thread tape and slip the handle back over the stem. In most cases, a single wrap creates a snug fit.
Fast fix for an annoying problem