The Best Plumbing Inspection Prep Checklist for 2026

Why I Created This Plumbing Inspection Prep Checklist

I've inspected hundreds of homes over the last 12 years. In my experience cleaning and organizing properties for sale, plumbing issues kill deals faster than anything else. I remember a specific closing in 2019 where a $40,000 sale fell through because of a slow drain and a missing drip leg on the water heater. It's frustrating. You don't want to lose money over a $15 part. That's exactly why I put together this plumbing inspection prep checklist.

I'll be honest, this takes elbow grease. But spending three hours on a Saturday saves you thousands in renegotiation credits. If you have kids who track mud everywhere and clog the tub drain weekly, you already know plumbing takes a beating. Let's get your pipes ready for the magnifying glass.

The 48-Hour Plumbing Inspection Prep Checklist

I break my prep work into specific zones. Tackling everything at once leads to missed details.

Kitchen and Laundry Areas

• Check the garbage disposal. Run it with cold water and a cup of ice cubes for 45 seconds. This sharpens the blades and clears gunk.
• Inspect the dishwasher drain hose. It needs a high loop. I use a simple $4 zip tie to secure the hose to the underside of the counter. If it lays flat on the floor, dirty sink water backs up into your clean dishes.
• Look under the kitchen sink. Feel the P-trap for moisture. I keep a roll of plumber's tape (specifically Oatey 1/2-inch thick white tape) in my caddy. If I feel a drip, I tighten the slip nut a quarter turn.
• Check the washing machine hoses. If they are rubber and over five years old, swap them. I always install Stainless Steel Washing Machine Hoses from SupplyWorks. They cost about $25 for a pair and prevent catastrophic flooding.

Bathrooms and Toilets

• Test every toilet for rocking. Straddle the bowl and shift your weight. If it moves even a millimeter, the wax ring is compromised. I pull the toilet and install a Fluidmaster 7530P8 Universal Wax-Free Seal. It costs $12 and never leaks, unlike traditional wax rings that melt in summer heat.
• Check shower caulking. Inspectors hate black mold. I scrape out old caulk with a 5-in-1 painter's tool and apply GE Silicone II Kitchen & Bath caulk. It cures in 30 minutes and blocks moisture.
• Run the exhaust fans. Hold a single square of toilet paper to the grille. If it doesn't stick, the motor is failing or the vent is clogged. I usually just swap the motor for a $25 Broan replacement unit.
• Look for slow drains. Pour a kettle of 190-degree water down the tub spout. If it pools, use a Zip-It drain snake. It's a flimsy $3 piece of plastic, but it pulls out hair clumps better than a $200 auger.
• Inspect supply lines. Look at the braided stainless steel supply lines under the sink. If they are cheap, unbranded lines from a big box store, I swap them for BrassCraft ProConnect lines. They cost $8 each and have a much thicker inner polymer core that won't burst under 120 PSI of municipal water pressure.

Water Heater and Main Shutoff

• Locate the main water shutoff valve. Turn it off and on twice. If it's stuck, spray the stem with WD-40 Specialist Silicone Lubricant. An inspector will absolutely test this, and a broken valve means the water department has to shut off the street main.
• Check the water heater T&P valve. Lift the lever slightly. Water should flow out the discharge pipe and stop when you let go. If it keeps dripping, the valve is shot. I replace these with a Watts 0.5 in. LF15S-M1 for about $18.
• Verify the drip leg. It must be a vertical pipe dropping down from the gas line on gas water heaters. I've seen inspectors fail homes over a missing $8 black iron nipple.
• Check the expansion tank. Tap it with your knuckles. The top half should sound hollow, and the bottom half should sound solid. If the whole thing sounds solid, the bladder is ruptured. I swap it with an Amtrol Extrol #15 tank, which runs around $45.
• Inspect the anode rod. I check the anode rod every three years. If it's more than 50% consumed, I swap it for a $30 aluminum-zinc rod from Home Depot. This stops the tank from rusting out and prevents that rotten egg smell.

Tools and Supplies You'll Actually Need

I don't believe in buying tools you'll use once. Here is the exact kit I keep in my 18-inch Stanley soft-sided toolbox for plumbing prep.

Item	Brand/Model	Price Range	Why I Use It
Pipe Wrench	Ridgid 10-inch Aluminum	$45 - $55	Lightweight but grips stubborn galvanized fittings without slipping.
Drain Snake	BrassCraft 25ft Drum Auger	$30 - $40	Fits easily into tight vanity cabinets where bulky machines won't go.
Teflon Tape	Oatey Yellow Gas Line Tape	$4 - $6	Thicker than white tape, preventing gas leaks on water heater connections.
Moisture Meter	General Tools MMD4E	$25 - $35	Catches hidden leaks behind drywall before the inspector finds them.

Common Red Flags Inspectors Look For (And How I Fix Them)

Inspectors have a mental checklist. I've shadowed enough of them to know exactly what makes them pull out their red pens.

Double Tapping on Water Lines

This happens when two supply lines are jammed under a single shutoff valve nut. It causes slow leaks. I always install a brass add-a-valve adapter. It costs about $12 at Home Depot and gives you a dedicated port for the dishwasher or ice maker.

Missing Anti-Scald Valves

If your home was built before 2005, you might not have pressure-balancing shower valves. Inspectors flag this as a safety hazard. I swap out old Moen or Delta trim kits for their modern Posi-Temp or Monitor 14 series equivalents. The rough-in valve replacement takes about 90 minutes if you have to cut drywall, but it's worth it.

Improper Venting

Every drain needs a vent to prevent siphoning the P-trap. If a sink gurgles when the toilet flushes, it's poorly vented. I install a Studor AAV (Air Admittance Valve) under the sink. It's a $15 fix that stops the gurgling instantly and passes code in most municipalities.

Corroded Galvanized Pipes

I'll be honest, this is a nightmare scenario. If you have gray, threaded pipes that look like they're covered in crusty white snow, they are galvanized steel. Inspectors will demand a full repipe. You can't prep your way out of this. I recommend hiring a crew to swap them for PEX-A (specifically Uponor ProPEX) before the inspection. It costs $4,000 to $8,000, but it saves the sale.

The Sewer Scope: Don't Ignore the Underground Lines

I've lost count of how many deals fell apart at the 11th hour because of a collapsed sewer line. A standard plumbing inspection prep checklist usually stops at the foundation wall. But the buyer will likely hire a separate company to run a Ridgid SeeSnake camera down the main line.

If you have large oak or willow trees within 30 feet of the street, roots are probably in your clay pipes. I recommend proactively renting a 100-foot auger from Sunbelt Rentals for about $75 a day. Run a cutting blade through the 4-inch cleanout to clear any minor root intrusions before the buyer's camera catches them. If the line is completely collapsed, you'll need to trench or use trenchless pipe bursting, which costs $150 to $250 per linear foot.

Final Walkthrough: The Day Before the Inspection

The night before the inspector arrives, I do one last sweep.

• Clear out the cabinets under every sink. Inspectors need to see the back wall and the drain lines. I box up all the cleaning supplies and move them to the garage.
• Wipe down the pipes. I use a damp microfiber cloth to remove dust and cobwebs from the exposed P-traps. A clean pipe looks like a well-maintained pipe.
• Leave the water heater access panel off. If it's an electric tank, the inspector needs to see the wiring and the anode rod connection. Just make sure the power is turned off at the breaker if you remove the actual electrical cover plate.
• Label the main shutoff. I use a $3 pack of red and white adhesive labels from Avery. Writing 'MAIN WATER SHUTOFF' in sharpie takes ten seconds and makes the inspector's job easier. Happy inspectors write shorter reports.

Plumbing Inspection Prep Checklist: FAQ

How long does a plumbing inspection usually take?

In my experience, a thorough plumbing inspection takes about 45 to 90 minutes for a standard 2,000-square-foot home. The inspector will test every fixture, check the water heater, and examine the main sewer line if a camera scope is included. If they find major issues like active leaks or outdated polybutylene pipes, it can stretch past two hours.

Should I hire a plumber to prep the house, or can I do it myself?

I highly recommend doing the basic visual checks and minor fixes yourself using this plumbing inspection prep checklist. However, if you discover a cracked cast iron sewer line or a failing water heater, hire a licensed professional. A licensed plumber's receipt showing recent repairs carries massive weight with both the inspector and the buyer.

What happens if the inspector finds a minor leak?

Minor leaks, like a dripping P-trap or a weeping toilet fill valve, won't kill your sale. The inspector will note it as a repair item in the final report. You can then either fix it yourself before closing or offer the buyer a $50 to $100 credit to handle it.

Do I need to prep the outdoor hose bibs?

Yes, exterior plumbing is absolutely part of the inspection. I always turn on both the hot and cold outdoor spigots to check for low pressure and ensure the anti-siphon vacuum breakers aren't spraying water everywhere. If the vacuum breaker leaks, you can unscrew it and replace the internal rubber gaskets for about $4.