A dripping compression faucet is the most common plumbing complaint in homes built before 1980, and also the easiest plumbing repair a homeowner can tackle. Compression faucets use a rubber washer pressed against a brass seat to stop the flow of water, and that rubber washer is a wear part with a predictable lifespan of 3 to 8 years. After 20 years of service calls on these fixtures, I can walk you through how they work, why they fail, and how to fix or replace one without paying a plumber’s hourly rate.
How Compression Faucets Work
Turn the handle of a compression faucet and a threaded stem moves up or down inside the body of the faucet. At the bottom of the stem sits a rubber washer (typically a flat disc 1/2 inch or 3/4 inch in diameter) held in place by a brass screw. When the handle is fully closed, the washer compresses against a brass seat at the bottom of the cylinder, sealing off the water flow.
Two-handle bathroom and kitchen faucets, exterior hose bibs, and most laundry tubs use this design. You can identify a compression faucet by the handles: they turn multiple full rotations between fully open and fully closed, unlike modern cartridge or ball faucets that turn only a quarter or half turn.
Why Compression Faucets Leak
Leaks come from three places: the spout, around the handle, and at the base where the faucet meets the sink. A spout drip means the washer has hardened or chipped. A handle leak means the packing nut or O-rings inside the handle are worn. A base leak typically means the deck gasket or supply line connection is failing.
Calcium and mineral buildup on the brass seat is the second cause of spout drips. Even with a new washer, water sneaks past a corroded seat. Resurfacing the seat with a seat-grinding tool or replacing the seat (a separate removable part on most compression faucets) restores the seal.
Washer Replacement Step by Step
Shut off water at the angle stops below the sink, or at the main if the angle stops are seized. Open the faucet handle fully to drain residual water. Pop the decorative cap on top of the handle to expose a Phillips screw. Remove the screw and lift the handle off the stem.
Unscrew the packing nut (typically a hex nut at the base of the stem) with an adjustable wrench or basin wrench. Lift the stem out, exposing the washer at the bottom held by a brass screw. Replace the washer with the exact size and shape that came out. Use bibb washers from Danco, BrassCraft, or Plumb Pak; a multi-pack runs $4 to $7 at any hardware store.
While the stem is out, check the brass seat at the bottom of the cylinder with a small flashlight. If you see pitting, scoring, or a green ring of corrosion, replace the seat with a seat wrench (a square or hex tool that fits the inside of the seat) or grind the seat with a brass seat grinding tool. Both tools cost $8 to $20.
Choosing the Right Washer
Washers come in beveled and flat profiles, and in sizes from 0 (3/8 inch) up to 1/2 inch. Take the old washer to the store to match it. Beveled washers seal better on slightly worn seats and are the better choice for older faucets. Flat washers work on newer seats with sharp edges.
Use Buna-N rubber washers for cold water; they handle the constant compression cycle better than standard rubber. Avoid economy bin washers; they harden within a year. Genuine BrassCraft or Lasco washers cost about $1 more per set and last three times longer.
Packing Replacement for Handle Leaks
If water seeps out around the handle when the faucet is on, the packing inside the handle needs replacement. Modern compression faucets use a packing washer or O-ring; older fixtures use graphite-impregnated packing string wrapped around the stem.
Remove the handle and packing nut, slide the old packing off, and replace it. For O-ring style, take the old O-ring to the store and match the diameter. For string packing, wrap 2 to 3 turns around the stem in the same direction the packing nut tightens. Reassemble and test.
When to Replace Versus Repair
Replace the entire faucet when the body shows green corrosion through the chrome plating, when the supply tubing is galvanized and crumbling, or when both stems have failed seats that resist resurfacing. A new two-handle compression-style faucet from Delta, Moen, or Glacier Bay runs $35 to $120 at home centers.
For a true upgrade, swap to a quarter-turn cartridge faucet. Modern Delta Foundations or Moen Adler kitchen faucets at $80 to $180 install in under 90 minutes with basic hand tools and eliminate washer replacement for the next 10 to 15 years. Cartridge faucets use ceramic discs that wear far slower than rubber washers.
Tools You Need
Stock these in your toolbox for compression faucet repair:
- Adjustable wrench, 8-inch
- Basin wrench (for under-sink supply nuts)
- Phillips and flat-head screwdrivers
- Seat wrench (square and hex configurations)
- Seat grinding tool with multiple thread sizes
- Multi-pack of bibb washers and matching brass screws
- Plumber’s grease (food-grade silicone like Danco Waterproof Grease)
Common Mistakes
Overtightening the handle to stop a drip is the most damaging habit. The extra force does not seal a worn washer; it deforms the brass seat and accelerates failure. If you have to crank the handle hard to stop the drip, replace the washer that day. Continuing to torque the handle ruins the seat and turns a $2 repair into a $15 seat replacement or a full faucet swap.
Using Teflon tape on the wrong threads is the second common error. Tape the faucet threads where they meet supply lines, but never the seat threads or stem threads. Plumber’s grease, not tape, lubricates the stem threads and packing.
Exterior Hose Bibs and Sillcocks
Outdoor hose faucets are almost always compression-style. The same washer replacement procedure applies, but you need to shut off water at the interior shutoff valve (look for a separate stop in the basement or crawl space, usually with a small drain plug). Frost-free sillcocks have a long stem that puts the washer inside the heated wall; the washer at the spout end is just a backup. Replace the long stem if the faucet drips and the interior shutoff is closed.
Compression faucets are old technology, but they remain serviceable, cheap to repair, and durable when maintained. Knowing your way around a compression faucet saves a $150 plumber call every few years and keeps an aging fixture useful for another decade. When repairs start stacking up, upgrade to a quarter-turn cartridge faucet for long-term reliability and faster operation.
