Maintenance procedure · Written to ASD-STE100 Issue 9 · Formatted to ANSI Z535

Stopping a Dripping Tap

Compression, ball, cartridge and ceramic disc taps — find the type, then find the part
ApplicabilityHousehold basin, sink and bath taps with a stop valve below the fixture
Task timeat least 44 min to 58 min (47 of 48 steps estimated) editorial estimate, not a measurement
PersonnelOne
Revisionv1 · 2026-07-29
BEFORE YOU BEGIN

Before you begin. This procedure is general reference information, not professional advice. Equipment varies by manufacturer, model, and year. Always follow the documentation supplied with your equipment — where it differs from this page, follow the manufacturer. Verify that you have the tools, the working conditions, and the ability to do this task safely. If anything is unclear, if the equipment is damaged, or if the task exceeds your experience, stop and use a qualified professional. You are responsible for your own safety and for the outcome. This site accepts no liability for any loss, damage, or injury arising from the use of this information.

Specifications marked unverified could not be traced to a manufacturer source. Do not rely on them — obtain the value from your equipment documentation.

Summary

A tap drips because one soft part inside it has stopped sealing — a washer, an O-ring, or the whole cartridge. It is not an expensive fault and it is not an urgent one, but it is a steady one: EPA reckons a faucet dripping once a second throws away more than 3,000 gallons in a year. The mechanical work is easy. The part that defeats people is buying the right part, and that is what most of this page is about.

There are four internal designs in ordinary household taps and they fail differently, so the first job is to work out which one you are holding. After that the difficulty is that a cartridge is keyed to a brand and very often to a single production range within that brand, and no page can look at your sink and tell you which. So we will not print a part number, and we will not print a tightening figure for the bonnet nut either. What we will do is show you where the leak points, how to get the old part out intact, and how to reach the maker's own parts diagram — including the trap where the number stamped on your spout turns out to be a plumbing standard rather than a model number.

Safety

NOTICE

MAKE A PHOTOGRAPH AT EACH STAGE OF THE DISASSEMBLY.
The parts of a tap go together in one order only.

Necessary equipment

ItemNote
Adjustable wrenchThe wrench must open wide enough for the bonnet nut.
Screwdriver setA tap handle uses a slot screw, a cross screw or a hex screw.
Hex key setA single-handle tap frequently has a hex screw below the lever.
Masking tapePut the tape on the jaws of the wrench.
Old towelsPut the towels in the base of the cabinet.
FlashlightThe space below a basin is dark.
Mobile phone with a cameraMake a photograph at each stage of the work.
Needle-nose pliers optionalUse the pliers to hold a small spring or a small seal.
Repair part from the parts list for your tap materialThe part must be the part for your make and your model.
Grease that your tap manufacturer approves materialAn incorrect grease makes a rubber seal soft.

Find the source of the leak

Estimated 4 min

NOTEThe place of the leak tells you which part has wear. A drip at the spout and a drip at the handle have different causes.
  1. Close the handle of the tap fully.
    <1m
  2. Dry the tap and the basin with a towel.
    <1m
  3. Look at the tap for one minute.
    1m
  4. If water comes from the end of the spout, the seal at the seat has wear.
    • A compression tap has a washer at this position.
    • A cartridge tap or a ceramic disc tap has the seal inside the cartridge.
    <1m
  5. If water comes from the base of the handle, the packing or the O-ring has wear.
    <1m
  6. If water comes from the base of the spout, the O-ring at the spout has wear.
    <1m
  7. Make a record of the position of the leak.
    <1m

Find the type of tap

Estimated 3 min

NOTEHousehold taps have four internal designs. TM 3-34.70 divides them into the compression tap and three washerless types. The washerless types are the ball tap, the cartridge tap and the ceramic disc tap.
  1. Count the handles on the tap.
    <1m
  2. Turn each handle from the closed position to the fully open position.
    <1m
  3. If a handle turns more than one half turn, the tap is a compression tap.
    • A compression tap has two handles and a washer on each stem.
    <1m
  4. If a handle stops after one quarter turn, the tap is a ceramic disc tap.
    <1m
  5. If one handle moves up and to each side, the tap is a ball tap or a cartridge tap.
    • A ball tap has a small dome below the lever and a set screw in the side.
    • The two types look almost the same from the outside.
    <1m
  6. Make a record of the type of tap.
    <1m

Close the stop valve

Estimated 4 min

  1. Put the old towels in the base of the cabinet below the basin.
    <1m
  2. Find the two stop valves below the basin with the flashlight.
    • One stop valve is for the hot supply and one is for the cold supply.
    • If the basin has no stop valve, stop this procedure.
    1m
WARNING

CLOSE THE TWO STOP VALVES BEFORE YOU DISASSEMBLE THE TAP.
Water stays in the tap after you close the valves. Hot water can burn your skin.

NOTICE

DO NOT USE FORCE ON A STOP VALVE.
A stop valve that does not move is a job for a plumber.

  1. Turn each stop valve clockwise until the valve stops.
    1m
  2. Open the handle of the tap fully.
    <1m
  3. Let the water in the tap go into the basin.
    <1m
  4. Make sure that no water comes from the spout.
    <1m
  5. Close the handle of the tap.
    <1m

Disassemble the tap

Estimated 10 min to 18 min

NOTICE

CLOSE THE DRAIN STOPPER BEFORE YOU REMOVE A SCREW.
A small screw that falls into the drain is difficult to get.

  1. Close the drain stopper of the basin.
    <1m
  2. Remove the cap from the top of the handle.
    • The cap is a small disc with a red mark or a blue mark on it.
    • A ball tap has a set screw in the side of the lever and no cap.
    1m
  3. Remove the screw below the cap.
    1m
  4. Remove the handle from the tap.
    1m
NOTICE

PUT TAPE ON THE JAWS OF THE WRENCH.
A wrench with no tape makes marks on the surface of a tap.

  1. Put the tape on the jaws of the wrench.
    <1m
  2. Loosen the bonnet nut with the wrench.
    2m
  3. Remove the bonnet nut by hand.
    <1m
  4. Remove the cartridge or the stem from the body of the tap.
    • Some cartridges have a clip that you must remove first.
    • Some cartridges need a straight pull with a steady force.
    2m
  5. Make a photograph of the parts before you move them.
    <1m
NOTICE

EXAMINE THE SEAT BEFORE YOU INSTALL A NEW PART.
A rough seat destroys a new washer quickly.

  1. Look into the body of the tap with the flashlight.
    <1m
  2. Examine the seat at the bottom of the body.
    • A seat with a rough surface or a mark does not seal a new washer.
    • A seat with damage needs a seat tool or a plumber.
    1m

Get the correct part

Estimated 10 min to 17 min (partly estimated)

NOTETake the used part with you. A cartridge fits one brand, and frequently only one range of production.
Repair part for your tap
Unverified — do not rely on this value
CONSULT THE PARTS LIST FROM THE MANUFACTURER OF YOUR TAP, OR MATCH THE USED PART AT THE COUNTER

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Model number of your tap
Unverified — do not rely on this value
CONSULT THE DOCUMENTATION FOR YOUR TAP. THE NUMBER A112.18.1 ON A SPOUT IS A STANDARD DESIGNATION AND NOT A MODEL NUMBER

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

  1. Find the make of the tap on the body or on the handle.
    1m
  2. Find the model number in the documentation for the tap.
    • Moen states that the number A112.18.1 on a spout is not a model number.
    • The model number is usually on the box, on the receipt or in the installation guide.
    3m
  3. Open the parts list from the manufacturer of your tap.
    • Delta and Moen both give a step-by-step tool for a tap with no model number.
    4m
  4. Take the used part to the parts counter.
  5. Get the repair part for your make and your model.
    • A part from a different range of production does not seal.
    2m

Assemble the tap

Estimated 6 min

Torque for the bonnet nut on your tap
Unverified — do not rely on this value
CONSULT THE TAP MANUFACTURER DOCUMENTATION. TIGHTEN BY HAND, THEN A SMALL AMOUNT WITH THE WRENCH

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

Chemical compatibility of a grease with the seals in your tap
Unverified — do not rely on this value
CONSULT THE TAP MANUFACTURER DOCUMENTATION

No tier-1 source was found for this value. Take it from the documentation supplied with your equipment.

NOTICE

TIGHTEN THE BONNET NUT BY HAND FIRST.
Too much force on the nut distorts a cartridge and makes a new leak.

  1. Put the new part into the body of the tap.
    • A cartridge has a position mark. Put the mark to the front.
    2m
  2. Install the bonnet nut by hand.
    1m
  3. Tighten the bonnet nut with the wrench a small amount.
    <1m
  4. Install the handle on the tap.
    1m
  5. Install the screw and then the cap.
    1m

Do the final checks

Estimated 7 min

  1. Close the handle of the tap.
    <1m
  2. Turn each stop valve counter-clockwise slowly.
    1m
  3. Look at the two stop valves for one minute.
    1m
  4. Open the handle of the tap. Let the water flow for one minute.
    1m
  5. Close the handle of the tap again.
    <1m
  6. Dry the tap and the basin. Look at the tap for two minutes.
    2m
  7. Open the drain stopper of the basin.
    <1m

Terminology

This page uses one term for each item and holds it throughout, as ASD-STE100 requires. Equipment sellers and other guides use the names below for the same parts.

dripping tap
Also called: leaky faucet, leaking faucet, dripping faucet, leaky tap, running tap, faucet drips, tap won't stop dripping
cartridge
Also called: faucet cartridge, valve cartridge, tap cartridge, faucet insert, stem cartridge, the bit inside the faucet
compression tap
Also called: washer tap, washer faucet, compression faucet, two-handle faucet, old style tap, rubber washer tap
washer
Also called: tap washer, faucet washer, rubber washer, seal washer, the little rubber disc
seat
Also called: valve seat, faucet seat, seat washer surface, the metal ring the washer presses on
O-ring
Also called: o ring, oring, rubber ring, seal ring, spout seal
bonnet nut
Also called: retaining nut, packing nut, gland nut, cartridge nut, the big nut under the handle
stop valve
Also called: shutoff valve, shut off valve, angle stop, supply valve, isolation valve, the little tap under the sink

When to use a professional

Stop if the basin has no stop valve. The work then needs an isolation point that is not at the fixture, and that is not on this page.

Stop if a stop valve does not close. Stop if a stop valve leaks when you turn it. Stop if a stop valve turns with no effect. Speak to a plumber.

Stop if the body of the tap has a crack. Stop if the seat has damage that you cannot remove. Stop if water comes from a supply pipe. Speak to a plumber.

Do not do work on the supply pipes above the stop valve. Do not remove the tap from the basin. Do not use a chemical to loosen a part.

This page does not give a part number for your tap. This page does not give a torque figure. This page does not name a grease. Ask the manufacturer of your tap for these three answers.

Common questions

How much water does a dripping faucet actually waste?

More than people expect. EPA's WaterSense programme puts a faucet dripping at one drip per second at more than 3,000 gallons a year, and household leaks generally at more than 9,300 gallons. That is the reason to fix a drip that is otherwise only annoying. It is also why a slow weep around the handle, which never makes a sound, is worth the same attention as an audible drip from the spout.

How do I know what kind of faucet I have?

Turn the handle and count. The US Army's plumbing manual splits household taps into compression taps, which use a rubber washer squeezed onto a seat, and three washerless designs: ball, cartridge and ceramic disc. If a handle turns round and round for half a turn or more before the water stops, it is a compression tap and the part you want is a washer. If it stops firmly after about a quarter turn, it is a ceramic disc. A single lever that lifts and swings is either a ball or a cartridge, and those two look almost identical from outside — the ball type usually has a small set screw in the side of the lever.

There's a number stamped on my faucet. Is that the model number?

Probably not, and this is the single most common wrong turn. Moen's own support library says outright that the numbering "A112.18.1", which can appear on the spout, the aerator or the spray wand, is not a model number — it is the plumbing standard the fitting was built to, and every compliant faucet from every maker carries it. The real model number is usually on the box, the receipt or the installation guide, and sometimes on the back of the spout or engraved under a removable handle cap. If you have none of those, use the maker's identifier tool instead of guessing.

Where do I get the right cartridge for my faucet?

From the manufacturer's own parts diagram, and not from a size chart. A cartridge is keyed to the brand and very often to one production range within it, so two faucets that look the same on the shelf can take different parts. Delta publishes a step-by-step identifier that walks you from room and product type to your model, and then to a product page with a parts list and a diagram; Moen has an equivalent. If you cannot get there, take the old cartridge out and carry it to a plumbing counter — the physical part answers the question that no web form can.

It only drips when the tap is turned off. What does that mean?

It means the seal that is supposed to shut the water off has stopped doing it, so the fault is at the seat or inside the cartridge rather than around the outside of the tap. On a compression tap that is almost always the washer on the bottom of the stem, and the Army manual is clear that you should also look at the seat itself while you are in there — a chipped or rough seat will chew up a brand new washer in weeks. On a washerless tap it is the cartridge or, on a ball type, the rubber seats and springs under the ball.

There is no shutoff valve under my sink. Can I still do this?

Not with this page. Everything here is written around isolating the one fixture at its own stop valve, so that if something goes wrong the water is already off and the rest of the house is unaffected. Without that valve you would be shutting off the supply for the whole property and working with no local isolation, which is a different job with a different risk profile. Get a plumber to fit stop valves; they are inexpensive, and having them makes every future repair at that sink a ten-minute job.

Sources

Every specification on this page is traced to one of these sources. Tier 1 is a manufacturer document, a published standard, or a government safety authority. See Standards for the full tiering rule.

  1. Tier 1Fix a Leak WeekWaterSense, United States Environmental Protection Agency · accessed 2026-07-29 · re-verification due 2027-01-25
  2. Tier 1Bathroom FaucetsWaterSense, United States Environmental Protection Agency · accessed 2026-07-29 · re-verification due 2027-01-25
  3. Tier 1Sink FaucetsMoen Incorporated (Moen Solutions support library) · accessed 2026-07-29 · re-verification due 2027-01-25
  4. Tier 1Find Parts and Identify Your ProductDelta Faucet Company (Masco Corporation) · accessed 2026-07-29 · re-verification due 2027-01-25
  5. Tier 1Replacing a faucet aeratorNEOPERL GmbH · accessed 2026-07-29 · re-verification due 2027-01-25
  6. Tier 1TM 3-34.70 / MCRP 3-17.7E, Plumbing, Pipe Fitting, and SewerageHeadquarters, Department of the Army (Army Publishing Directorate) · accessed 2026-07-29 · re-verification due 2027-01-25

Revision history

Current version 1 · updated 2026-07-29 · next review due 2027-07-29

  1. v1 · 2026-07-29First draft. Tap type taxonomy and the seat inspection cross-read from TM 3-34.70 chapter 7, which is archaic and publishes no value here. Identification route and the A112.18.1 trap from Moen's own support library; the parts-diagram route from Delta Faucet. Leak volume from EPA WaterSense. No part number, torque figure or grease publishes as a verified value. Written independently in Simplified Technical English; no source sentence was paraphrased.

Corrections to this page are listed in the public corrections log. Reports that are credible and not yet verified are listed in the public errata register, and an open one renders above the step it concerns.

Comments and corrections

Found an error? A correction with a manufacturer source is applied and logged publicly. You can also write to corrections@fixchecklist.com.

Every step above carries its own report control, which tags the report with that step so a correction reaches the right place. For anything about the procedure as a whole — the order of the sections, a step that is missing, something that did not match your equipment — use this: report something about this whole procedure.

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