A leaking pipe, a backed-up sewer line, a water heater that gives you nothing but cold showers — plumbing problems are stressful because they disrupt your daily life and they can cause serious property damage fast. The average NJ homeowner will hire a plumber at least a few times over the life of their home, and the difference between a good plumber and a bad one is measured in thousands of dollars, property damage, and headaches.
New Jersey regulates plumbing more strictly than most states. Plumbers must be licensed at the state level through the Board of Examiners of Master Plumbers, and your municipality may have additional requirements. But most homeowners don't know how to verify any of this — they just Google “plumber near me,” call the first result, and hope for the best.
This guide gives you a concrete checklist for choosing a plumber in NJ. Eight things to verify before you hire, the red flags that should make you hang up the phone, what plumbing work actually costs in this state, and how to tell the difference between a fair price and a ripoff.
8 Things to Check Before Hiring a Plumber in NJ
1. Verify Their NJ Master Plumber License
This is the single most important check, and it's the one most people skip. In New Jersey, all plumbing work must be performed by or under the direct supervision of a licensed master plumber. This is state law, not a suggestion. The NJ Board of Examiners of Master Plumbers oversees licensing, and the requirements are serious.
New Jersey has two levels of plumbing licenses:
- Master Plumber: This is the full license. A master plumber has completed a minimum of five years of apprenticeship and journeyman work, passed a rigorous state exam, and is authorized to pull permits, run a plumbing business, and supervise other plumbers. This is the person whose license the business operates under.
- Journeyman Plumber: A journeyman has completed their apprenticeship and can perform plumbing work, but only under the supervision of a licensed master plumber. They cannot pull permits or operate independently.
Why this matters to you: If an unlicensed person performs plumbing work on your home, your homeowner's insurance may deny any claim related to that work. If the work was done without a permit (which only a master plumber can pull), your municipality can require you to rip it all out and redo it. And if you ever sell your home, unpermitted plumbing work can kill a deal or reduce your sale price.
How to verify: Ask the plumber for their NJ master plumber license number. Then verify it on the NJ Division of Consumer Affairs License Verification portal. Search under “Board of Examiners of Master Plumbers.” The status should say “Active.” If it says expired, revoked, or you can't find them — do not hire them.
Also check the NJ Home Improvement Contractor (HIC) registration. Plumbing companies that do home improvement work also need a valid HIC registration under the Contractors' Registration Act. A legitimate company will have both.
2. Confirm Insurance Coverage
Plumbing work involves cutting into walls, working under foundations, soldering near framing, and connecting to your home's main water and sewer lines. Things can go wrong even with skilled plumbers — a torch can scorch a joist, a sewer camera can reveal a bigger problem mid-job, or a supply line can fail during repair. Without proper insurance, you are financially responsible for any damage or injuries that happen on your property.
Every plumber you consider hiring must carry:
- General liability insurance: Covers property damage caused by the plumber's work. If they accidentally flood your basement or damage a wall, this pays for it. Look for at least $500,000 in coverage, though $1 million is standard for reputable companies.
- Workers' compensation insurance: Covers injuries to the plumber or their employees while working on your property. If a plumber's apprentice gets hurt in your home and the company doesn't have workers' comp, you could be sued.
How to verify: Ask the plumber for a Certificate of Insurance (COI). Any legitimate plumbing company will produce one within minutes — their insurance company can email or fax it directly to you. If they hesitate, say they'll “get it to you later,” or claim they don't need insurance, end the conversation.
Pro tip: Call the insurance company on the certificate and confirm the policy is current. Certificates can be outdated or fabricated. A 60-second phone call protects you from a potentially catastrophic liability.
3. Read Reviews (But Read Them the Right Way)
Everyone checks Google reviews, but most people do it wrong. They glance at the star rating and move on. A 4.8 with 200 reviews sounds great, but what matters more is the content and pattern of the reviews.
What to look for in reviews:
- Specificity. Good reviews mention the actual work done: “replaced our water heater in 3 hours, cleaned up everything, explained the warranty.” Vague five-star reviews like “Great service!” with nothing else may be fake.
- Recency. A plumber with 200 reviews but nothing in the last 6 months may have changed ownership, lost their best technicians, or declined in quality. Focus on the last 3–6 months.
- How they handle complaints. Every company gets a bad review eventually. What matters is how they respond. A professional response that acknowledges the issue and offers a resolution is a good sign. Defensive, dismissive, or no responses to negative reviews is a red flag.
- Patterns in negative reviews. If multiple people mention the same problem — surprise charges, no-shows, unfinished work — believe them. One complaint is an anomaly. Three complaints about the same thing is a pattern.
Where to check: Google Business Profile (most important), Yelp, the Better Business Bureau (BBB) website, and Angi (formerly Angie's List). Cross-reference across platforms. A plumber with great Google reviews but an F rating on the BBB deserves deeper investigation.
4. Get a Written Estimate (Always)
This is where a lot of homeowners get burned. The plumber shows up, takes a look, quotes a number verbally, starts working, and then the final invoice is 40–60% higher. “Well, once I got in there, I found more problems.” Maybe. Or maybe the low verbal quote was bait.
A written estimate should include:
- A detailed description of the work to be performed
- An itemized list of materials and their costs
- Labor costs (hourly rate or flat fee for the job)
- Any permits required and their costs
- The total estimated cost
- A clear statement of what happens if additional work is discovered (do they stop and get your approval, or proceed and charge you?)
- An estimated timeline for completion
Under NJ consumer protection law, home improvement contractors (including plumbers) must provide a written contract for any job over $500. The contract must include the contractor's HIC registration number, a description of the work, the total price, and payment schedule. Failure to provide this is a violation of the New Jersey Consumer Fraud Act.
Pro tip: Get estimates from at least three plumbers for any non-emergency job. This gives you a price range and helps you spot outliers — the suspiciously low bid that will balloon later, and the inflated bid from the company that knows most people don't comparison shop.
5. Ask About Their Warranty
Any plumber confident in their work will warranty it. The warranty terms tell you a lot about the company's quality and integrity.
What to expect:
- Labor warranty: Most reputable plumbers offer a 1-year warranty on labor at minimum. Some offer 2–5 years on major installations like water heaters, sewer lines, or repiping jobs. If a plumber won't warranty their labor at all, they don't trust their own work — and neither should you.
- Parts/materials warranty: This usually comes from the manufacturer (e.g., a water heater with a 6-year or 12-year manufacturer warranty), but the plumber should help you understand what's covered and assist with warranty claims if something fails.
Get the warranty in writing. A verbal promise of “we stand behind our work” is worth nothing if the company denies responsibility six months later. The written estimate or contract should specify exactly what's warrantied, for how long, and what the process is if you need warranty service.
Red flag: If a plumber says “we don't do warranties” or “it's guaranteed for 30 days,” move on. Thirty days is barely enough time to confirm the repair holds. A company that won't stand behind their work for at least a year either knows their quality is poor or plans to be gone before problems surface.
6. Evaluate Their Response Time and Communication
How a plumber communicates before they get the job tells you exactly how they'll communicate after. This is one of the most reliable indicators of quality.
Good signs:
- They answer the phone or return your call within a few hours (same day for non-emergencies)
- They ask detailed questions about your problem before quoting a price
- They give you a specific arrival window, not just “sometime Tuesday”
- They explain what they'll need to do and approximately how long it will take
- They follow up after giving an estimate, even if you haven't decided yet
Bad signs:
- You can't get a human on the phone and no one calls back for days
- They quote a price without seeing the problem or asking any questions
- They give vague timelines: “we'll get there when we can”
- They seem annoyed by your questions
- They pressure you to commit immediately: “I have another job starting tomorrow, so I need an answer now”
The plumber who takes time to explain things, shows up when they said they would, and communicates clearly throughout the job is almost always the plumber who does good work. Professionalism in communication correlates directly with professionalism in the work.
7. Understand Their Pricing Model: Upfront/Flat-Rate vs. Hourly
Plumbers in NJ generally use one of two pricing models, and understanding the difference can save you from sticker shock.
Hourly pricing:
- You pay for the actual time the plumber spends on the job, plus materials.
- NJ plumber hourly rates typically range from $80 to $150 per hour, depending on the company, the plumber's experience, and your location. North Jersey (Bergen, Essex, Morris counties) tends to run higher than South Jersey.
- Advantage: If the job is straightforward and fast, you only pay for actual time worked.
- Risk: If the job takes longer than expected (or the plumber works slowly), your bill climbs with every hour. You don't know the final cost until the work is done.
Flat-rate / upfront pricing:
- The plumber diagnoses the problem, then quotes a single price for the entire job — labor and materials included.
- Advantage: You know the cost before any work begins. No surprises. If the job takes longer than the plumber estimated, that's their problem, not yours.
- Risk: Flat-rate prices build in a margin for unexpected complications, so you may pay slightly more than if the job went perfectly on hourly billing.
Our recommendation: For most homeowners, flat-rate/upfront pricing is safer. You trade a potentially small savings for certainty. The plumber absorbs the risk of complications, not you. Just make sure the flat-rate quote is in writing and includes everything — no “additional charges may apply” fine print.
8. Confirm Emergency Availability
This may not matter for a scheduled repair, but it matters enormously the next time your sewer backs up at 11 PM on a Saturday or a pipe bursts during a January cold snap. When you find a good plumber, you want to know they'll be there when it's an emergency — not just during convenient business hours.
Ask:
- Do you offer 24/7 emergency service?
- What's your after-hours response time?
- Is there an additional charge for emergency/after-hours calls? (Most companies charge a premium — typically $100–$200 on top of the normal rate. This is standard and expected.)
- Will I get a licensed plumber, or do you subcontract emergency calls to a third party?
A plumber who offers true 24/7 service with their own licensed staff is worth keeping in your contacts. Build that relationship now — during a non-emergency scheduled repair — so you have a trusted number to call when a real emergency hits.
Red Flags: When to Walk Away
Not every plumber who shows up at your door deserves your trust or your money. Here are the warning signs that should make you stop, reconsider, and call someone else.
No License (or Won't Show It)
If a plumber can't or won't provide their NJ master plumber license number, end the conversation immediately. There is no legitimate reason for a licensed plumber to withhold this information. It's public record and they should be proud to share it. Unlicensed plumbing work puts your home, your insurance coverage, and your family's safety at risk.
Won't Provide a Written Estimate
Any plumber who insists on working without a written estimate or contract is setting you up for a billing dispute. The verbal “around $300” becomes $750 on the invoice, and you have zero documentation to dispute it. NJ law requires a written contract for jobs over $500 — a plumber who ignores this legal requirement will ignore other standards too.
Demands Full Payment Upfront
A reasonable deposit for large jobs (10–30% for major installations) is normal. Demanding full payment before any work begins is not. A plumber who wants all the money upfront has zero incentive to finish the job properly or come back if something goes wrong. Never pay more than a third of the total cost before work begins. The balance should be due upon satisfactory completion.
No Warranty on Work
As covered in the checklist above, refusing to warranty labor is a disqualifying red flag. It means they either don't trust their own quality or they plan to be unreachable when problems arise.
Pressure Tactics
“This price is only good today.” “If you don't fix this now, it'll cost triple next week.” “I had a cancellation so I can fit you in right now, but only if you commit.” These are sales tactics, not plumbing advice. A legitimate plumber gives you the facts, gives you an estimate, and gives you time to decide. Urgency is manufactured to prevent you from getting competing quotes.
Unmarked Vehicle, No Uniform, No Business Card
Professional plumbing companies invest in branded vehicles, uniforms, and printed materials because they plan to be in business for years. A plumber who shows up in a personal truck with no company markings, no uniform, and no business card may be a moonlighter working without a license or insurance. This is especially common after major weather events when demand spikes.
NJ Plumbing Licensing: Master vs. Journeyman and How to Verify
Understanding New Jersey's plumbing license structure helps you ask the right questions and spot unqualified operators.
Master Plumber License
The master plumber license is the highest level of plumbing credential in New Jersey. Requirements include:
- Minimum 5 years of practical experience working under a licensed master plumber
- Passing the NJ Master Plumber examination (a comprehensive written and practical exam covering the NJ Plumbing Code, safety, and installation practices)
- Background check
- Maintaining continuing education credits for renewal
A master plumber can:
- Own and operate a plumbing business
- Pull plumbing permits from your municipality
- Supervise journeyman plumbers and apprentices
- Sign off on completed work for inspections
Journeyman Plumber
A journeyman plumber has completed their apprenticeship training (typically 4–5 years) and is qualified to perform plumbing work, but must do so under the supervision of a licensed master plumber. A journeyman cannot pull permits or operate a plumbing business independently.
When a plumbing company sends a journeyman to your home, that's fine — as long as the company is operated by a licensed master plumber whose license covers the work. The master plumber doesn't have to be physically present for every job, but they are legally responsible for the quality of work performed under their license.
How to Verify Any Plumber's License
- Go to the NJ Division of Consumer Affairs License Verification portal.
- Under “Profession,” select “Master Plumbers.”
- Enter the plumber's name or license number.
- Check that the status is “Active” and note the expiration date.
- If you can't find them, they are either unlicensed or their license has lapsed. Either way, do not hire them for plumbing work.
This verification takes about 60 seconds and is the single best thing you can do to protect yourself.
How Much Do Plumbers Charge in NJ? (2026 Rates)
Knowing what plumbing work costs in New Jersey helps you evaluate whether a quote is fair, inflated, or suspiciously low. Here are current rate ranges based on the NJ market:
Hourly Rates
- Standard service call: $150–$500, which typically includes the first hour of labor plus a diagnostic fee. Many companies fold the diagnostic fee into the repair cost if you hire them for the job.
- Hourly rate (after initial service call): $80–$150 per hour. This varies by region: North Jersey metro areas and affluent suburbs tend toward the high end. South Jersey and more rural areas trend lower.
- Emergency/after-hours rate: $150–$250 per hour, plus an emergency dispatch fee of $100–$200. Expect to pay roughly 1.5–2x the standard rate for nights, weekends, and holidays.
Common Job Costs in NJ
- Unclog a drain: $150–$350 (simple snake) or $300–$600 (hydro-jetting for severe clogs)
- Fix a leaking faucet: $150–$300
- Toilet repair: $150–$350
- Water heater replacement (tank): $1,200–$2,500 installed
- Water heater replacement (tankless): $2,500–$5,000 installed
- Sewer line repair: $2,000–$7,000 depending on method (trenchless vs. traditional dig)
- Whole-house repipe: $4,000–$10,000+ depending on home size and pipe material
- Sump pump installation: $500–$1,500
If a quote is dramatically below these ranges, ask why. It could mean the plumber is cutting corners on materials, isn't licensed (and therefore has lower overhead because they're not paying for insurance, licensing, permits, etc.), or is giving you a low-ball bid that will inflate once work starts.
Common Plumbing Scams in NJ (And How to Avoid Them)
The plumbing industry has its share of bad actors. Here are the scams NJ homeowners encounter most often:
The “Sewer Camera” Scam
A plumber runs a camera through your sewer line and shows you footage of cracks, root intrusion, or “bellies” (sagging sections). They declare you need a full sewer line replacement for $5,000–$15,000. The problem? Some of these “defects” are normal wear that doesn't require replacement, or worse, the footage may not even be from your property.
Protection: Get a second opinion from an independent plumber before agreeing to any sewer line replacement. Ask to watch the camera feed in real time and have them explain what they're seeing. A honest plumber will walk you through the footage and explain what actually needs fixing versus what's cosmetic.
The “While I'm Here” Upsell
You call for a simple faucet repair. The plumber “notices” that your water pressure is low, your shut-off valves are old, your pipes are corroding, and your water heater is “about to go.” Your $200 faucet repair balloons into a $3,000 wish list of recommended work, delivered with urgency: “I'd hate for you to have a major leak after I leave.”
Protection: Tell them to fix what you called about and only what you called about. For any additional “recommended” work, get it in writing and get separate quotes from other plumbers. Legitimate additional findings do happen — but the honest plumber documents them and lets you decide on your timeline, without pressure.
The Bait-and-Switch Estimate
The plumber quotes a low price to get the job, then “discovers” complications once they've already started. Now your walls are open, your water is shut off, and you're told the job will cost twice the estimate. You feel trapped — which is exactly the point.
Protection: Your written estimate should include a clause requiring the plumber to stop and get your written approval before proceeding with any additional work beyond the original scope. If the estimate doesn't include this, add it. If they refuse, hire someone else.
The “Cash Discount”
A plumber offers a significant discount — 20–30% off — if you pay cash and skip the receipt. This means no paper trail, no warranty enforcement, no permit pulled, and no recourse if something goes wrong. The “discount” is actually the plumber avoiding taxes and accountability.
Protection: Always pay by check or card so you have a transaction record. Always get a receipt. The 20% you “save” in cash isn't worth losing all consumer protections.
The Door-Knocker After a Storm
After a major storm, freeze event, or flooding, unlicensed operators go door-to-door offering “emergency” plumbing repairs at bargain rates. They do quick, shoddy work, collect cash, and disappear. When the repair fails two weeks later, their phone number is disconnected.
Protection: Never hire a plumber who solicits you door-to-door. Legitimate plumbing companies don't need to canvass neighborhoods — they have enough demand from referrals and reputation. In an emergency, call a plumber you've vetted or use a service like MainStreet that pre-screens every contractor.
8 Questions to Ask Before Hiring Any Plumber
Before you hire a plumber in NJ, ask these questions. A professional plumber will answer all of them clearly and without hesitation. If you get evasiveness, irritation, or vague answers, that tells you everything you need to know.
- “What is your NJ master plumber license number?” — Non-negotiable. Verify it on the NJ DCA portal before they start work.
- “Can you provide a certificate of insurance?” — They should have general liability and workers' compensation. Ask for the certificate before the appointment.
- “Will you provide a written estimate before starting?” — The answer must be yes. If they want to “take a look first,” that's fine — the estimate comes after the diagnostic, before the repair.
- “Is this a flat-rate quote or hourly?” — Know what you're agreeing to. If hourly, ask for a time estimate so you have a ballpark total.
- “What happens if you find additional problems during the work?” — The right answer: “We stop, explain what we found, give you a revised estimate, and wait for your approval before proceeding.”
- “What warranty do you offer on the work?” — Get the terms in writing. At minimum, one year on labor.
- “Will you pull the required permit?” — For any work that involves modifying your plumbing system (not just simple repairs like fixing a faucet), a permit is typically required. The plumber should handle this.
- “How long have you been in business, and can you provide references?” — Longevity matters. A company that's been serving NJ homeowners for 10+ years has a track record you can check. References should be recent (within the last year) and for similar work.
Emergency Plumber vs. Scheduled Service: When to Call Each
Not every plumbing problem is an emergency, and calling for emergency service when you don't need it costs you $200–$400 extra in after-hours fees. Here's how to tell the difference:
Call an Emergency Plumber (Now) If:
- A pipe has burst or is actively leaking and you cannot stop the water. Shut off the main water valve first (every homeowner should know where this is), then call. Water damage escalates by the minute.
- Your sewer line is backed up into your home. Raw sewage in your living space is a health hazard. This can't wait until Monday.
- You have no hot water in winter and someone in the home is elderly, an infant, or medically vulnerable. NJ winters are dangerous without hot water and heat.
- You smell gas near a water heater or gas line. This is a safety emergency. Leave the house, call your gas company first (PSE&G: 1-800-880-7734, New Jersey Natural Gas: 1-800-427-5325), and then call a plumber.
- A fixture is flooding and the shut-off valve doesn't work. If you can't stop the water at the fixture level and the main shut-off is inaccessible or also failing, this is an active emergency.
Schedule a Regular Appointment If:
- A faucet is dripping but not flooding. Annoying and wasteful, but it can wait a day or two.
- A toilet runs intermittently. Usually a flapper valve issue. Not urgent.
- A drain is slow but not completely blocked. Schedule a drain cleaning during normal business hours.
- You want to replace a water heater that still works. Plan the upgrade on your timeline, get multiple quotes, and schedule it during business hours to avoid emergency premiums.
- You're renovating or want to add/move plumbing fixtures. This is planned work that requires permits and should be scheduled in advance.
The cost difference is real. A scheduled drain cleaning during business hours might run $150–$300. The same job as an emergency weekend call could be $400–$600. Save emergency calls for actual emergencies.
How MainStreet Service Pros Pre-Screens Plumbers for You
We built MainStreet because most homeowners don't have time to run through an 8-point vetting checklist for every plumber they might hire. So we do it for you.
Every plumber in the MainStreet network has been verified for:
- Active NJ master plumber license — confirmed through the NJ Division of Consumer Affairs, not just self-reported
- Current general liability and workers' compensation insurance — certificates on file and re-verified periodically
- NJ Home Improvement Contractor registration — current and in good standing
- Review history and reputation — we check Google, BBB, and Yelp. Pattern complaints (billing disputes, no-shows, unfinished work) disqualify a contractor from our network
- Written estimate policy — every MainStreet plumber provides a written estimate before starting work. No exceptions
- Warranty on labor — minimum one-year warranty on all work performed
When you call MainStreet for a plumber, you skip the vetting process because we've already done it. You get connected with a licensed, insured, reviewed, and warranty-backed NJ plumber who will show up on time, give you a written estimate, and stand behind their work.
We don't charge homeowners for the connection. The plumber pays a referral fee for the introduction. You get the same quality of work at the same price you'd pay calling the plumber directly — minus the hours of research, phone calls, and license verification.
Frequently Asked Questions
Do I need a licensed plumber for every plumbing job in NJ?
By NJ law, any work that involves modifying, repairing, or installing plumbing systems must be done by or under the supervision of a licensed master plumber. Simple tasks like replacing a showerhead, swapping a toilet flapper, or tightening a compression fitting are considered routine maintenance and don't require a license. But anything involving supply lines, drain lines, gas lines, water heaters, or fixture installation should be done by a licensed plumber. When in doubt, hire a licensed pro — the cost of getting it wrong (water damage, code violations, voided insurance) far exceeds the cost of hiring properly.
How do I verify if a plumber is licensed in New Jersey?
Go to the NJ Division of Consumer Affairs License Verification portal. Select “Master Plumbers” under the profession dropdown, enter the plumber's name or license number, and confirm the status shows “Active.” This takes about 60 seconds and is free. You should also check their NJ Home Improvement Contractor (HIC) registration on the same portal.
What should I do if a plumber causes damage to my home?
Document the damage immediately with photos and video. Contact the plumber in writing (email or certified mail) describing the damage and requesting repair or compensation. If they have proper insurance (which you verified before hiring them, right?), file a claim against their general liability policy using the Certificate of Insurance you obtained. If they are unresponsive or refuse to address the damage, file a complaint with the NJ Division of Consumer Affairs. If they are a registered HIC, you have additional consumer fraud protections available.
Is it worth paying more for a plumber with better reviews?
Almost always, yes. A plumber who charges $100/hour and does the job right the first time costs you less than a plumber who charges $70/hour, does a poor repair, and forces you to pay someone else to redo it. Factor in the cost of water damage from a botched repair, and the “cheaper” plumber becomes the most expensive mistake you could make. Quality plumbing work is an investment that pays for itself in avoided problems.
Can I do my own plumbing work in NJ to save money?
Homeowners can perform certain plumbing work on their own primary residence without a license, but there are important caveats. You may still need a permit from your municipality, and the work must pass inspection. If you sell your home, unpermitted plumbing work must be disclosed, and buyers (or their inspectors) will flag it. If the work was done improperly and causes damage, your homeowner's insurance may deny the claim. For anything beyond the most basic repairs (replacing a faucet, unclogging a drain with a hand snake), hiring a licensed plumber is the safer and smarter choice.
What's the difference between a plumbing estimate and a plumbing quote?
An estimate is an approximation — the plumber's best guess at what the job will cost based on what they can see. The final price may be higher or lower. A quote (or “firm bid”) is a fixed price — the plumber commits to completing the specified work for exactly that amount, barring unforeseen complications that require your approval. Always ask which one you're getting. A firm quote in writing is always better than a verbal estimate. If a plumber gives you an estimate, ask what the maximum cost could be and whether they'll cap it.
How quickly should a plumber respond to an emergency call?
For a true plumbing emergency (burst pipe, active flooding, sewer backup, gas leak smell near water heater), a reputable emergency plumber in NJ should be able to arrive within 1–2 hours during business hours and 2–4 hours after hours. Response times vary by location — urban and suburban NJ areas have faster response because more plumbers operate there. If you're calling at 2 AM on Christmas Eve, expect the longer end of the range. Any company that can't provide even an estimated arrival time is not equipped for emergency service.
Should I get a plumbing inspection before buying a home in NJ?
Absolutely. A standard home inspection covers plumbing at a surface level, but a dedicated plumbing inspection by a licensed master plumber goes deeper — literally. They can run a sewer camera to check the main line for root intrusion, bellies, cracks, or collapsed sections. They can check water pressure, inspect the water heater age and condition, evaluate the pipe material (galvanized steel pipes in older NJ homes are a ticking time bomb for corrosion and low pressure), and identify any code violations from previous DIY or unlicensed work. A plumbing inspection costs $200–$500 and can reveal problems that would cost $5,000–$20,000 to fix after you've closed. It's one of the best investments you can make during the home-buying process.