Shower head leaking or dripping — San Francisco, California

A shower head that drips constantly even when the faucet is turned off is more than an annoyance — it wastes a surprising amount of water (a drip per second adds up to over 3,000 gallons per year) and creates persistent moisture that encourages mold growth, mineral staining, and grout deterioration in the shower enclosure. The most common cause is a worn-out rubber washer or O-ring inside the shower valve that no longer creates a watertight seal when the handle is in the off position. In single-handle cartridge valves, the cartridge itself may be scored or calcified. Mineral buildup (calcium and lime deposits) inside the shower head body or at the threaded connection to the shower arm can also cause water to seep past the seal. A plumber can usually fix the problem in 30–60 minutes by replacing the valve washer, O-ring, or cartridge ($150–$250 for a service call including parts). Homeowners comfortable with basic tools can often replace a washer themselves for under $5 in parts, but cartridge replacement in a wall-mounted valve is best left to a professional to avoid damaging the valve body or in-wall plumbing.