Fixture Installation & Repair

75 min read Training Guide

Install and repair the residential plumbing fixtures customers actually call about - faucets, sinks, toilets, garbage disposals, and shower trim - cleanly and leak-free the first time.

Table of contents

Fixture Installation & Repair

A fixture call is the most customer-facing work in plumbing. The homeowner watches you walk in. They watch the drop cloth go down. They watch where you set tools. They use the toilet you installed an hour after you leave. If the seal weeps, if the faucet drips, if you scratch their granite with a wrench, you do not get the call back next time. The work itself is not hard. Doing it cleanly, the first time, with no leaks and no callbacks, is the whole job.

This guide walks the install and repair routines for the fixtures a first-year apprentice or maintenance tech sees every week: faucets (kitchen and bath), toilets, sinks (drop-in, undermount, vessel), garbage disposals, shower and tub trim, plus the common repair calls that keep a service truck busy.

The Mindset

Fixtures are visible work. Nobody sees the copper soldered behind the wall. Everybody sees the toilet you set and the chrome you handled with bare greasy fingers. The mindset that separates a fixture installer from a pipe runner:

Clean as you go. Wipe primer and silicone off chrome and porcelain immediately. Cured silicone on a faucet body does not come off without scraping it and scratching it.
Drop cloth always. Tile, hardwood, vinyl, carpet, all of it gets a drop cloth. A mechanical room does not. A kitchen does. If you scratch a finished floor with a tool that fell off your bag, you pay for the floor.
Hand tight first, then snug. Brass and plastic threads strip quickly. Almost every fixture connection is hand tight plus a quarter to half turn with a wrench. Channel locks set to maximum gorilla pressure cracks porcelain and snaps brass.
Leak-free first time. A leak found during your test is a fix you make in five minutes with a tool already in your hand. A leak found by the homeowner at 9 pm is a callback, an apology, and possibly a damaged ceiling below.
Test before you sign off. Every supply, every drain, every joint, under pressure, before tools go back in the truck.

Tools and Supplies on a Fixture Call

You do not need every tool in the truck. You need the right ones in a small bag you can carry through a finished house without scuffing a wall.


| Item                              | What it is for                                       |
|-----------------------------------|------------------------------------------------------|
| Basin wrench                      | The only tool that reaches faucet nuts under a sink  |
| 10 in and 12 in channel locks     | Slip-joint nuts on traps and supply lines            |
| Small adjustable wrench (6 or 8)  | Compression nuts in tight spots                      |
| Tubing cutter (mini)              | Cutting copper or chrome supply stubs                |
| Plastic tubing cutter             | PEX, PVC trap arms, plastic supply lines             |
| Phillips and flat screwdrivers    | Faucet handles, escutcheons, mounting brackets       |
| Allen key set (SAE and metric)    | Set screws on faucet handles and shower trim         |
| Plumber's putty                   | Sink strainers and some drains (NOT on stone)        |
| 100% silicone (clear and white)   | Stone tops, vessel sinks, perimeter caulk            |
| PTFE tape (white, water-rated)    | Threaded supply connections                          |
| Pipe dope                         | Threaded steel and brass joints                      |
| Wax ring (regular and extra-thick)| Toilet flange seal                                   |
| Waxless seal (Fluidmaster, Korky) | Toilet seal for repeat resets or odd flange heights  |
| Closet bolts and brass washers    | Toilet to flange                                     |
| Braided supply lines (12, 16, 20) | Faucet and toilet supplies                           |
| 1/4 turn angle stops              | Shutoff valve replacements                           |
| Flapper, fill valve, flush valve  | Toilet repair stock parts                            |
| Towels and rags                   | A lot of them                                        |
| 5 gal bucket                      | Catches water under traps and supplies               |
| Drop cloth or red rosin paper     | Floor protection                                     |
| Headlamp                          | Inside cabinets, you cannot hold a flashlight        |
| Knee pads                         | Under sinks and at toilets, all day every day        |

Stock the truck with chrome, brushed nickel, and matte black handle screws and escutcheon caps. The job that needs that one $2 part you do not have becomes a second trip.

Faucet Swap (Kitchen and Bath)

The most common service call after toilet repair. Routine looks the same on both kitchen and bath:

Shutoffs off. Reach under, turn both angle stops clockwise until they stop. Open the faucet at the handle. Water should slow to a stop in a few seconds. If it keeps running, the angle stops are not holding. Turn off the main and replace them as part of the job.
Bucket and towels under. Even with the stops off, the lines have water in them. The supply lines drip. The faucet body has standing water. Catch all of it.
Disconnect supply lines. Use the small adjustable on the compression nuts at the angle stop and at the faucet shanks (or the basin wrench if the faucet shank nuts are deep). Loosen, swing the line out, drain into the bucket.
Disconnect the lift rod (bath only). The pop-up linkage runs from the back of the faucet down behind the drain. Unscrew the strap nut and drop the linkage.
Mounting nuts off. Reach up under the sink to the back of the faucet body. Plastic or brass nuts hold the faucet down. Basin wrench. Counterclockwise.
Lift the old faucet out. Wipe the deck clean. Scrape any old putty or silicone off with a plastic scraper, never metal on a finished surface.
Set the new faucet. Read the manufacturer's instructions for any deck gasket or putty. Most modern faucets ship with a rubber gasket and need no putty.
Mounting nuts on. Hand tight from below, then a quarter turn with the basin wrench. Center the faucet on the deck before snugging.
Reconnect supply lines. New braided stainless lines every time. Hand tight plus a quarter to half turn. Do not crank them.
Reconnect the pop-up linkage. Check that the stopper opens and closes fully through the lift rod range.
Open the angle stops slowly. Watch every connection while pressure builds.
Run the faucet. Hot, cold, both. Check spray pattern. Pop the aerator off and flush any debris from the supply lines for 30 seconds before reinstalling. New angle stops and new lines often have shavings inside.
Wipe everything down. Look under the sink with a headlamp at every joint after the faucet has run for a couple of minutes. No drips, no weeping, no swelling at the connection.

A faucet swap is 30 to 45 minutes once you have done a hundred of them. Your first ones will take 90.

Toilet Install

Heavy, awkward, and unforgiving. Drop the bowl on tile and you crack the bowl, the tile, or both.

Pre-Install

Inspect the flange. The flange should sit on top of the finished floor, not below it. Flange below floor needs a flange extender. Flange above floor by more than 1/4 inch needs to be cut down or shimmed at the bowl.
Closet bolts. New brass closet bolts every install. Clip them into the flange slots, oriented so the bolt heads stand straight up.
Wax ring vs waxless. Wax is the proven seal for a one-time install. Waxless (Fluidmaster Better Than Wax, Korky, Sani Seal) is reusable, holds shape if you have to lift the bowl to recheck the bolts, and works better on flanges that sit a hair high or low. Both work. Shop preference dictates.

Set the Bowl

Place the wax ring on the flange (or stick the waxless seal to the bottom of the bowl, depending on type).
Lift the bowl, line up over both closet bolts, and lower straight down. Do not rock side to side; you will roll the wax.
Press down firmly to compress the wax, sit on the bowl if needed.
Slide the brass washers and nuts onto the closet bolts. Hand tight, then alternate sides a quarter turn at a time until the bowl is firm against the floor.
Stop tightening when the bowl no longer rocks. Overtightening cracks porcelain at the base. If the bowl still rocks, do not crank harder. Shim it.
Cut the closet bolts off above the nut with a hacksaw or oscillating tool. Snap the caps on.

Shim a Rocking Toilet

Plastic toilet shims slide under the bowl at the rocking point. Snap or trim flush. A bowl that rocks even slightly will eventually break the wax seal and leak at the floor.

Tank to Bowl

Set the rubber tank-to-bowl gasket on the flush valve nut on the bottom of the tank.
Insert the tank bolts through the tank and through the bowl.
Brass washers and nuts go on the underside of the bowl.
Hand tight, then alternate sides until the tank sits firm against the bowl. Stop when firm. Cracking the tank on a tank-to-bowl bolt is a $200 mistake on a high-end toilet.

Supply Line and Final

New braided supply line from the angle stop to the tank inlet.
Hand tight at both ends, plus a quarter turn.
Open the angle stop. Tank fills.
Flush three times. Watch the base for any seep at the wax line. Watch the tank-to-bowl bolts inside and out.
Run the bowl through one full fill cycle. Check the fill valve shutoff height (water should stop about an inch below the top of the overflow tube).

Caulk Debate

Some shops caulk the perimeter of the base. Some leave the back open so a leak shows. Many local codes require caulking. The compromise everybody can live with: caulk three sides, leave a small gap at the back so a hidden leak is visible. Use 100% silicone, not latex, and tool with a wet finger.

Sink Install

Three styles, three different routines.

Drop-In (Self-Rimming)

The rim of the sink sits on top of the counter and supports the weight. Caulk seals the rim to the counter.

Set the sink dry in the cutout to confirm fit and clip locations.
Bead 100% silicone around the underside of the rim.
Lower the sink into the cutout, press down evenly.
From below, set the clips into the lugs and tighten until snug. Do not overtighten and crack the cast iron or the rim.
Tool the silicone bead at the rim with a wet finger immediately. Wipe excess with a rag and a touch of mineral spirits before it skins.
Install strainer (next section), supply lines, and trap.

Undermount

The sink hangs below the counter, supported by clips into anchors epoxied to the underside of the stone. Most undermount installs are done by the stone fabricator at the shop. Field installation is for replacement only and you need to confirm the support clips are in place and rated for the new sink's weight.

Apply 100% silicone around the lip of the sink (the part that contacts the underside of the counter).
Lift the sink into position from below, press up against the counter, and hold with a brace or sink harness while the clips are tightened.
Tighten clips evenly to compress the silicone bead.
Wipe the excess that squeezes into the bowl with mineral spirits before it cures.
Install drains, supplies, and trap.

Vessel

A bowl sitting on top of the counter, no rim recessed in. The drain comes up through a hole in the counter into the bottom of the bowl.

Mounting ring or rubber gasket between the bowl bottom and the counter.
Set the bowl, center it on the drain hole.
From below, snug the drain assembly up to the bowl and to the counter underside.
Connect the trap and check level.

Strainer Install

Standard kitchen strainer or bath drain.

Plumber's putty rolled into a 3/8 inch rope around the underside flange of the strainer. Skip the putty and use 100% silicone if the counter is granite, marble, quartzite, or any porous stone, or if the sink is plastic. Putty stains stone and breaks down some plastics.
Press the strainer into the drain hole from above. Putty squeezes out.
From below, slip on the rubber washer, then the friction washer, then the lock nut.
Hold the strainer body from above with a strainer wrench (or a pair of channel locks crossed over the crossbars) while you tighten the lock nut from below.
Wipe the squeezed-out putty from the inside of the sink with a rag.

P-Trap Recap

The trap arm (horizontal piece between the trap and the wall stub-out) slopes down toward the wall at 1/4 inch per foot. Maximum length is set by code based on trap arm size. The trap holds a water seal against sewer gas; the slope returns water to the trap on every drain.

Garbage Disposal Install

Half plumbing, half electrical. Read the manual that comes with the unit; mounting collars vary by brand (InSinkErator has its own twist-lock; Waste King uses an EZ Mount).

Knock out the dishwasher inlet plug if a dishwasher is being connected. This is the single most common rookie mistake. The disposal ships with a plug in the dishwasher inlet. If a dishwasher is feeding into the disposal and you forget to knock that plug out, the dishwasher backs up into the unit and floods the cabinet on the first wash. Use a screwdriver and a hammer to drive the plug out from outside, then reach in and remove the broken plug from inside the disposal so it does not jam the impeller.
Mount the sink flange. Plumber's putty or 100% silicone (stone counters: silicone) around the underside. Press through the sink hole. From below, snap the mounting assembly on per the manufacturer's instructions and tighten the support ring evenly.
Wire the disposal. If hardwired, connect to the conduit at the bottom of the unit (black to black, white to white, ground to green screw). Wire nuts and a strain relief at the cord port. If plug-in, attach a cord whip to the bottom of the disposal first, then plug in.
Hang the unit on the mount ring. Twist into place per the brand. The unit should lock with a positive click.
Connect the drain. Discharge tube from the disposal to the trap or to a continuous waste tee. Slip washers and nuts.
Connect the dishwasher hose (if applicable) to the dishwasher inlet on the side of the disposal. Hose clamp tight.
Run water and test. Confirm no leaks at the sink flange, dishwasher inlet, and drain. Run the disposal briefly with water flowing. Listen for grinding, scraping, or odd vibration.

Shower and Tub Trim

Trim swaps are common service work, especially cartridge replacement.

Cartridge Swap (Single-Handle Mixing Valve)

Water off. Main, or the dedicated shower valve isolators if the rough-in has them.
Open the handle to drain residual.
Pull the handle. Pop the cap, remove the screw, lift the handle off.
Remove the escutcheon. Most are threaded; some are screw-mounted. Wrap with a rag if you need to grip with channel locks to avoid scratching.
Remove the retaining clip or nut holding the cartridge in place.
Pull the cartridge. A cartridge puller is the right tool when it is stuck. Channel locks rocking it out works on freer ones.
Install the new cartridge. Note the orientation arrows or hot/cold markers. Lubricate O-rings with silicone plumber's grease, never petroleum jelly.
Reassemble in reverse.
Set the scald-guard. Most modern cartridges have a rotational stop ring that limits maximum hot water output. Adjust per manufacturer instructions to limit shower output to a safe maximum (105 to 110 deg F is typical). This is required by most plumbing codes (ASSE 1016 / IPC) for new installs and recommended on swaps.
Test through the full handle range before reinstalling the trim. Hot, cold, and mid.
Caulk the escutcheon to the wall with 100% silicone. Tool with a wet finger.

Tub Spout

Slip-on spouts have a set screw on the underside; loosen with an Allen key, slide off.
Threaded spouts unscrew counterclockwise, often needing a long Allen key or a piece of pipe through the spout for leverage.
Apply PTFE tape or pipe dope to the new threads (threaded), or set the new slip-on and tighten the set screw.
Caulk the spout to the wall at the base.

Common Repair Calls

Running Toilet

The number-one service call. Diagnose in this order:

Look in the tank. Is water running into the overflow tube? The fill valve is set too high or has failed. Adjust the fill valve down, or replace it.
Listen between flushes. Phantom flushing or tank refilling without anyone using it means water is leaking from the tank into the bowl. The flapper has failed or is dirty.
Drop dye in the tank (food coloring or a dye tablet). Wait 15 minutes without flushing. If color appears in the bowl, the flapper is leaking. Replace it.
Check the chain length. Too short and the flapper will not seat fully. Too long and the chain gets caught under the flapper. There should be a tiny amount of slack with the flapper closed.
Inspect the flush valve seat. A pitted or corroded seat will not seal even with a new flapper. The fix is a flush valve replacement, which means draining the tank, removing the tank from the bowl, and swapping the entire flush valve assembly.

A 90% of running-toilet calls resolve at flapper or fill valve. Both are $10 parts and a 15 minute fix.

Faucet Drip

Diagnose by faucet style:

Cartridge faucet (single handle): replace the cartridge. Match by faucet brand and model.
Compression faucet (two handles, requires multiple turns to shut off): replace the rubber washers and seats. Old style; common on commercial and older residential.
Ball faucet: replace the springs, seats, and ball assembly.
Ceramic disc faucet: replace the disc cartridge.

For modern residential, 95% of drip calls are cartridge faucets, and the cartridge is the fix.

Pop-Up Assembly

A bathroom sink stopper that will not seat or will not stay open. Issues:

Lift rod too short or too long. Adjust the strap on the back of the faucet.
Spring clip slipped off the horizontal pivot. Reattach.
Pivot ball worn or pivot nut leaking. Replace the pivot rod assembly (cheap, $5).
Hair clogged on the stopper tail. Pull the stopper out, clean it, reseat.

Pressure and Leak Testing

Every fixture, every job, before you walk out:

Open all the angle stops. Slowly. Watch every connection as pressure builds.
Run the fixture through full operation. Faucet hot, cold, full handle range. Toilet flush twice. Disposal with water. Shower handle through full hot to cold.
Headlamp under the cabinet. Look at every joint, every supply, every trap connection. Touch with a clean dry rag and check for wetness on the rag.
Wait five minutes. Recheck. A slow weep does not show in 30 seconds.
Check the floor around the toilet base. Front, sides, back.
Check the ceiling below if there is a finished space below the bath or kitchen. A leak can show as a wet spot on the ceiling drywall before it shows visibly at the fixture.

If anything is wet, fix it. Now. With the tools still in your hand. Not later.

Signing Off

Last 10 minutes of the call:

Wipe the fixture down. Chrome, porcelain, deck, handles. The customer remembers a clean fixture, not a clean install routine.
Bag your trash. Old cartridges, old supply lines, old wax ring, packaging from new parts. Take it. Do not leave it in their bin.
Pull the drop cloth. Fold dirty side in.
Walk the customer through what was done. Show them the new parts. Show them the new shutoffs and how they work. "Here is your shutoff valve. If anything ever leaks, turn this clockwise to off." That two-minute walk-through is the difference between a one-call customer and a return customer.
Leave the work area cleaner than you found it.

That is fixture work. Done right, the only person who notices the install is the homeowner who turns the faucet on and gets clean cold water with no drips. That is the job.