How to Fix a Leaky Single-Handle Faucet: A DIY Guide

Quick Answer

A leaky single-handle faucet is usually caused by a worn-out O-ring or a faulty cartridge. The fix typically involves turning off the water supply, carefully disassembling the handle and spout, replacing the old O-rings or cartridge with new ones, and then reassembling the faucet. This common household repair can be completed in under an hour with basic tools.

The Problem

That constant drip, drip, drip from your single-handle faucet isn't just annoying; it's also a waste of water and can lead to staining in your sink or tub. Most single-handle faucets use a cartridge or a ball mechanism with O-rings to control water flow and temperature. Over time, these internal components can wear out or become caked with mineral deposits, losing their ability to create a watertight seal. This results in the telltale drip from the spout or leakage around the base of the handle.

Step-by-Step Fix

Safety Note: Always turn off the water supply to the faucet before beginning any repairs to avoid flooding.

1. Turn Off the Water Supply: Locate the shut-off valves underneath your sink (hot and cold). Turn them clockwise until the water flow stops completely. If your sink doesn't have individual shut-off valves, you'll need to turn off the main water supply to your house.
2. Cover the Drain: Place a rag or stopper in the sink drain to prevent small parts from falling into the drain while you work.
3. Remove the Handle Cap and Screw: Most single-handle faucets have a decorative cap on top of the handle. Carefully pry this off with a small flathead screwdriver or a utility knife to expose the handle screw. Unscrew the handle screw and lift off the handle.
4. Remove the Decorative Collar/Dome: Depending on your faucet model, you'll likely see a decorative collar or dome under the handle. This can usually be unscrewed by hand or with a pair of pliers. You might need to gently pry it up.
5. Access the Cartridge or Ball Assembly: Once the collar is removed, you'll see either a plastic or brass cartridge held in place by a retaining nut or clip, or a ball assembly with springs and O-rings.
   • For a Cartridge Faucet: Remove the retaining nut with adjustable pliers or a wrench, then pull the cartridge straight up and out. Note its orientation for reinstallation.
   • For a Ball Faucet: Remove the cap and cam assembly. You'll then see the plastic ball. Pry out the ball, and underneath you'll find springs and rubber seats/O-rings.
6. Inspect and Replace Worn Parts:
   • Cartridge: Take your old cartridge to a hardware store to ensure you buy an exact match. Install the new cartridge in the same orientation as the old one, ensuring it seats properly.
   • Ball Assembly: Remove the old springs, seats, and O-rings. Clean the area thoroughly. Install new springs (narrow side down), new rubber seats on top of the springs, and new O-rings around the ball if your kit includes them. Reinsert the ball.
7. Reassemble the Faucet: Reverse the disassembly steps. Replace the retaining nut (if applicable), decorative collar/dome, handle, and handle cap. Make sure all connections are hand-tight, then gently tighten with a wrench or pliers if necessary, being careful not to overtighten.
8. Restore Water Supply and Test: Slowly turn the water supply valves back on. Check for leaks around the handle and spout. If the leak persists, you may need to recheck your work or consider replacing the entire faucet.

Common Causes

The primary culprits behind a leaky single-handle faucet are:

• Worn-Out Cartridge: In cartridge-style faucets, the cartridge itself can wear down or crack over time, leading to internal leaks.
• Degraded O-rings: Rubber O-rings, found in both cartridge and ball-style faucets, become brittle, crack, or lose their elasticity, compromising the watertight seal.
• Mineral Buildup: Hard water can leave mineral deposits on internal components, preventing them from seating properly and causing drips.
• Loose Parts: Sometimes, a simple tightening of a retaining nut can solve a minor leak.

Tips & Prevention

• Keep Spare Parts: If you know your faucet's brand and model, keeping a spare cartridge or O-ring kit on hand can make future repairs quicker.
• Gentle Use: Avoid forcing the handle. Gentle use can prolong the life of internal components.
• Regular Cleaning: Periodically clean the aerator (the screen at the end of the spout) to remove mineral buildup, which can sometimes impact water flow and pressure.
• Water Softener: If you have exceptionally hard water, installing a water softener can reduce mineral buildup in your plumbing fixtures.

When to Call a Professional

If you've followed these steps and the leak persists, or if you encounter significant difficulty disassembling your faucet, it's time to call a licensed plumber. They have specialized tools and expertise to diagnose more complex issues, such as a damaged faucet body or internal pipe problems that are beyond a DIY fix.