Dripping Faucets: Shut Off First, Then Fix the Washer, Cartridge, or O-Ring

A dripping faucet is almost always a worn seal — a compression washer, cartridge, seats and springs, or an O-ring — not a mystery you solve by cranking the handle harder. Shut the water off at the under-sink stops (or the house main) before you open anything. Then match the repair to your faucet type. EPA WaterSense notes that old and worn faucet washers and gaskets frequently cause leaks, and that a faucet dripping once per second can waste more than 3,000 gallons a year.

I am not a licensed plumber. This guide is researched against EPA Fix a Leak guidance and manufacturer shutoff and repair instructions from Moen, Delta, and Kohler — not a “guaranteed fix in 10 minutes” checklist. This guide was substantially rewritten and re-fact-checked in August 2026.

Key takeaways

• Shut the water off first. Moen’s shutoff guide is blunt: any Moen faucet repair requires the supply off. Close the stops, then open the faucet to confirm flow is dead before you pull a handle.
• Diagnose by seal type, not by brand slogan. Spout drips with the handle off usually mean a worn cartridge, rubber seats and springs, or a compression washer. Leaks at the handle base or spout hub more often point to O-rings or packing.
• EPA waste framing is real money. EPA WaterSense puts one drip per second at more than 3,000 gallons per year — and notes household leaks can waste more than 9,300 gallons a year on average.
• Bring the old part (or clear photos) to the store. “Universal” cartridges and wrong-size washers are a common reason drips return the next week.
• Call a plumber for stuck shutoffs, cracked valve bodies, sealed-wall valves with no access, or drips that continue after correct OEM parts are installed.

Why a drip is worth fixing now

Noise is the least of it. Water that escapes past a closed valve still shows up on your bill, can stain fixtures, and can leave a damp cabinet base if the leak is at the spout hub or supply connections rather than the spout tip.

From EPA WaterSense Fix a Leak Week (content current as of the March 2026 campaign page):

• The average household’s leaks can waste more than 9,300 gallons of water a year.
• A faucet dripping at one drip per second can waste more than 3,000 gallons per year — EPA’s comparison is more than 180 showers’ worth of water.
• Old and worn faucet washers and gaskets frequently cause faucet leaks.
• EPA’s practical tip for faucet work: turn off the water line before you start.
• If step-by-step fixture repairs are not enough, EPA says it may be time to replace the fixture (look for the WaterSense label on a new faucet) and consult a professional for installation help.

Fixing an easy household leak can save about 10 percent on water bills in EPA’s framing — enough that a $10 seats-and-springs kit or washer pack often pays for itself quickly if the drip has been going for months.

Step 0: Shut off the water before any teardown

Every serious OEM repair path starts here. Skipping shutoff turns a calm Saturday job into a flooded cabinet.

Moen’s How to Turn Off the Water Supply to the Faucet says shutoffs are usually under the sink, in a closet or access panel for a tub/shower, or — if those do not exist — at the home’s main shutoff near the meter. Rotate stops clockwise until they are firmly closed, then open the faucet to confirm the water is completely off and to relieve pressure.

Delta’s seats-and-springs instructions and Kohler’s two-handle valve replacement guides repeat the same order: shut off the supply (or the whole house), cover the drain so clips and screws do not disappear, then remove the handle.

• Do not force a frozen under-sink stop with a big wrench. Snapping an old valve is a fast way to turn a drip into an emergency. Use the main shutoff and plan a plumber for the seized stop.
• Have towels and a small bucket ready. Residual water will still spill from the spout and lines after a good shutoff.
• If you cannot find a working shutoff quickly and water is streaming (not just dripping), close the house main first and troubleshoot later.

Identify your faucet type before you buy parts

The old version of this page listed four faucet types and then jumped into generic “replace worn parts” advice. That is how people buy a flat washer for a sealed cartridge faucet. Use this map first:

Type	How it usually looks	What usually fails on a spout drip
Compression (older two-handle)	Handles turn several rotations; stem screws down onto a seat	Flat rubber washer on the stem tip; sometimes a scored metal seat
Cartridge (very common single-handle kitchen/bath; many showers)	One lever or knob; stem pulls out as a cylinder	Worn cartridge (and its O-rings)
Ball (classic single-handle Delta-style)	Rounded ball under the handle cam	Rubber seats and springs under the ball; sometimes the ball
Two-handle stem with seats/springs (many Delta lavs)	Separate hot and cold; stem lifts after the bonnet	Seats and springs in the valve body; then stems if drip remains
Ceramic disc	Quarter-turn handles; disc cartridge inside	Usually the disc cartridge assembly, not a lone washer

Best confirmation: find the brand and model (tag on a supply line, underside of the deck, or old paperwork) and pull the parts diagram from Moen Solutions, Delta’s parts finder, or Kohler Assist. Your diagram wins over any generic blog sequence, including this one.

For the narrower symptom “handle fully off but water still runs,” see our companion guide: Faucet turned off but water still running.

Diagnose the drip: spout, handle, or base?

Where the water appears tells you which seal to chase. This is the cartridge / washer / O-ring decision most weekend repairs skip.

Where you see water	Likely seal	First repair path
Steady drip from the spout with handle(s) closed	Primary shutoff seal: washer, cartridge face, or seats/springs	Shut off; identify type; replace that sealing part
Slow stream that never fully stops	Same primary seal, sometimes plus grit on the seat	Shut off; clean ports; replace seats/cartridge/washer; flush
Water around the handle base when the faucet is off or on	Often packing or stem O-rings	Still shut off; inspect packing/O-rings after handle removal
Water under the spout hub / around the deck when the spout swings	Spout O-rings	Shut off; pull spout; replace O-rings with silicone grease
Drip only on hot or only on cold (two-handle)	That side’s washer, stem, or seats/springs	Feel which side of the spout runs warm; service that side first

On a two-handle sink, a practical homeowner check — used alongside Delta’s RP4993 seats-and-springs guidance — is to feel whether the drip runs warm or cold and start on that side. Reassemble and test before tearing into the other valve.

Honest O-ring note: O-rings get blamed first because they are cheap. They matter for hub and handle leaks. A spout that drips with the valve closed is more often the primary shutoff seal (washer, cartridge, or seats/springs). When you already have the faucet open, replace cut or flattened O-rings at the same time — but do not treat an O-ring swap as the whole diagnosis if water is clearly escaping past the closed valve into the spout.

Fix path A: Compression washer (and the metal seat)

Older multi-turn compression faucets still show up in baths and utility sinks. The stem screws a flat rubber washer down onto a metal seat. When the washer hardens, cracks, or sits crooked, the faucet drips with the handle “off.” That matches EPA’s language about worn washers and gaskets as a frequent faucet-leak cause.

High-level repair after shutoff:

1. Remove the decorative index cap (if present), handle screw, and handle.
2. Unscrew the packing nut / bonnet and back the stem out of the body.
3. Remove the screw holding the washer on the stem tip; replace the washer with the same size and shape (take the old one with you).
4. Inspect the metal seat in the faucet body. If it is rough or pitted, a seat-dressing tool or a replaceable seat (where the design allows) may be needed. Vinegar soaking alone will not reliably restore a scored seat.
5. Lightly grease threads where appropriate, reassemble, restore water, and test.

If the washer is new and the drip continues, the seat or stem is usually next — not “more force” on the handle. Over-tightening a compression faucet to stop a drip is how people strip stems and crack handles.

Fix path B: Cartridge replacement (Moen, Kohler, many single-handle valves)

Cartridge faucets seal inside a replaceable cylinder. When that cylinder wears, water bypasses even with the handle in the off position. Brand-specific details matter (retainer clips, bonnets, hot/cold orientation), but the safety frame is shared: supply off, pressure relieved, then pull the cartridge.

Moen example (1225 shower/standard valve cartridge). Moen’s 1225 cartridge article requires shutoff valves off before you remove the stop tube, D-washer, and copper retaining clip. After the old cartridge is out, Moen recommends cleaning and flushing the valve body before the new cartridge goes in. Reinstall with tabs aligned to the 12 and 6 o’clock slots; if the copper clip will not seat, do not turn the water back on until the clip is correctly installed. Stem notch orientation sets hot/cold — rotate 180° if they are reversed after reassembly.

Kohler example (deck faucet valve). Kohler’s valve-kit sheet (113780-9) opens with: shut off the water supply, lift the handle to relieve pressure, then remove set screw, handle, cap, sphere, and bonnet before pulling the valve. New valve posts must line up with holes in the body before you reassemble and restore supply. For common two-handle lav valves (GP77005-RP / GP77006-RP), Kohler Assist walks the same shutoff-first path: remove handle, remove adapter if present, unthread the valve counterclockwise, install the new valve about 1/8–1/4 turn past hand tight, restore water and check for leaks before putting the handle back on.

Practical cartridge tips that prevent repeats:

• Order the exact OEM part number or bring the old cartridge. “Universal” cartridges often fit poorly and leak again.
• Use silicone-based plumber’s grease on O-rings where the maker allows it. Delta explicitly says not to use petroleum-based lubricants on O-rings.
• Flush debris before the new cartridge seals against grit. Moen and Delta both build a flush step into cartridge/seat service for this reason.

Fix path C: Seats and springs (common Delta drip)

If your faucet uses Delta-style seats and springs, a spout drip with the handle off is exactly what Delta’s RP4993 kit article is written to solve. The kit covers many single-handle ball faucets, two-handle stem faucets, and some cartridge tub/shower valves — but Delta also warns that variations exist, so check your parts diagram first. Delta’s spout-drip overview likewise points two-handle owners toward seats/springs and stems.

Condensed from Delta’s published sequence (always after supply is off and the drain is covered):

1. Remove the handle (set screw with Allen wrench, or pry the index cap and remove the Phillips screw on knob styles).
2. Remove the adjusting ring if present (Delta says discard it on ball faucets), then the cap/bonnet.
3. Lift out the ball and cam (single-handle ball) or pull the stem straight up (two-handle stem).
4. Lift the old rubber seats and metal springs out of the ports. Wipe mineral deposits from the pockets with a soft damp cloth.
5. Install new springs large end first into the ports, then seats open/cup side down over the springs.
6. Reinstall ball/cam or stem with the correct orientation tabs, hand-tighten the cap/bonnet, replace the handle.
7. Remove the aerator, open the faucet to a mixed position, restore supply, flush about a minute, check for leaks, then reinstall the aerator.

If the drip continues after both sides’ seats and springs are new, Delta’s next step is replacing the stem assemblies — not endless re-greasing of dead rubber.

Fix path D: Ceramic-disc cartridges

Ceramic-disc faucets usually use quarter-turn handles over a disc cartridge. When they drip, you are typically replacing the disc cartridge assembly (and cleaning the neoprene seals underneath), not hunting for a flat compression washer. After shutoff:

1. Remove the handle and access the disc cartridge per your brand’s diagram.
2. Lift the cartridge, clean the seal pockets, and inspect seals for cuts or flat spots.
3. If cleaning does not stop the drip, replace the full disc cartridge with the OEM part.
4. Reassemble, restore water, and flush with the aerator removed.

Mineral grit under a disc seal can mimic a “bad cartridge.” Clean first; replace if the drip returns immediately.

Tools and parts checklist

• Adjustable wrench, Phillips and flat screwdrivers, Allen set
• Needle-nose pliers (retaining clips)
• Brand-correct cartridge, stem, seats-and-springs kit, or matching washers
• Silicone plumber’s grease (not petroleum jelly on rubber seals)
• White vinegar and an old toothbrush for light mineral cleanup on accessible seats/ports
• Rags, bucket, drain cover or rag in the drain
• Optional: strap wrench for finish-sensitive bonnets; manufacturer cartridge puller for stubborn Moen-style cartridges

When to stop and call a plumber

• Shutoff valves will not turn, leak when operated, or look corroded through.
• The valve is behind tile or a sealed wall with no access panel, and you would need demolition to reach stops or the valve body.
• The brass valve body is cracked, or threads strip when you remove a bonnet or stem.
• You restored OEM seats/cartridge/washer correctly and the faucet still will not shut off — at that point you may need a new faucet or a buried shower valve replacement, not another aftermarket “universal” part.
• You are dealing with a continuous stream and cannot locate a working shutoff quickly — treat it as an emergency and close the house main.

EPA’s Fix a Leak guidance also notes that if step-by-step fixture repairs are not enough, it may be time to replace the fixture (WaterSense-labeled when you buy new) and consult a professional for installation help.

How this was researched

I cross-checked shutoff-first and seal-replacement steps against EPA WaterSense Fix a Leak Week faucet guidance (washer/gasket causes, drip-per-second waste, shutoff tip), Moen Solutions (supply shutoff + 1225 cartridge), Delta support (RP4993 seats/springs and two-handle spout-drip procedure), and Kohler Assist / Kohler valve-kit documentation. Brand silence is respected where it applies: your exact model’s parts diagram wins over any generic sequence. No fabricated repair anecdotes — just the manufacturer order of operations a careful homeowner can follow.