Iowa plumbing license and contractor registration: what each lets you do, and your first 30 days

Published November 3, 2026 · Rules checked November 3, 2026

• Free. The full 30-day checklist is on this page, and the printable version (Google Docs, Word or PDF) comes by email.
• Deepsel is our product: free estimate, invoice and scheduling software for contractors (scheduling, quotes, invoicing, card payments). The section before the FAQ says where it fits and where it doesn't.
• Not legal advice. Every rule here links to the statute, rule, board page or city document it comes from. Ask the Plumbing and Mechanical Systems Board or an Iowa attorney before you bet a job on my reading.

The contractor registration you got from DIAL is not an Iowa plumbing license. It's the registration every Iowa contractor needs once they earn $2,000 a year from construction, and on its own it doesn't let you install or repair plumbing for pay. Plumbing is licensed by the Plumbing and Mechanical Systems Board, which licenses the people (apprentice, journeyperson, master) and the business (the contractor license). The contractor license needs a master plumber who is "actively in charge" of the work, $500,000 of public liability insurance, a $5,000 surety bond and a permanent place of business.^1,5,8 Plumbing contractors are meant to get the license and the registration on one joint application, so if that's how you got your C number, you hold both and the rest of this page is your first 30 days. If you registered through DIAL's own $50 registration, you probably don't have the license yet.⁹

The full checklist is further down. It's also a printable sheet with tick boxes and blanks for your license, bond, policy and permit numbers: make your own copy in Google Docs (lands in your Drive), download the Word version (.docx), or download the PDF. Pick a format, enter your email and I'll send the links.

I found almost nothing from Iowa plumbing owners online: in a two-year pull of Reddit's plumbing forums, not one Iowa owner stated a price. A plumber in another state put the rule most states share this way: "In my state you are required to hold a master's license to open a legit business" (Reddit). Iowa is one of those states. So this page is written from Iowa Code chapter 105, the board's rules (481 IAC chapters 425 to 434), DIAL's pages, two 2026 bills and four city codes, all read on November 3, 2026. The general side of the registration (who registers, the fee, lead paint, city contractor licenses) is in Iowa contractor registration, the paper you sign is in the Iowa contract template, and the electrician's side of a water heater or sump pump job is in Iowa electrical license.

Iowa contractor registration vs. plumbing contractor license: which one you have

Two credentials, both handled by DIAL. The contractor registration comes from chapter 91C: a number that's a "C" and six digits, an Iowa unemployment insurance account number (even with no employees), proof of workers' comp or a statement that you don't need it, and no exam.⁹ On its own it costs $50 and renews every year. But DIAL's registration page tells plumbing businesses not to use it: "If your business provides any type of plumbing, mechanical, HVAC, refrigeration, sheet metal or hydronic systems services, you are required to obtain a license with the Plumbing & Mechanical Systems Board. Complete a joint application for a 3-year registration and contractor license."⁹ The joint application is $250 for the license and $150 for three years of registration, and renewing the license renews the registration.^4,8

The license side is chapter 105: "a person shall not operate as a contractor or install or repair plumbing, mechanical, HVAC, refrigeration, sheet metal, or hydronic systems without obtaining a license issued by the board."¹ DIAL defines the contractor as "a person or entity that provides plumbing, mechanical, HVAC, refrigeration, sheet metal or hydronic systems services on a contractual basis and who is paid a predetermined amount under that contract."⁸ If you quote a price and do the work, that's you.

So which one might you be missing? It depends on who you are:

• You're a master plumber starting your own shop. You need the contractor license on top of your master license. As a sole proprietor you have to be the master yourself, and the insurance and bond have to be in your own name ("Mary Smith DBA Mary Smith Plumbing" is DIAL's example). As an LLC or corporation, they're in the company's name and cover all its plumbing work.^1,8 Apply on DIAL's license portal: $400 between July 1 and December 31, 2026.⁸
• You're a journeyperson plumber. You can't contract on your own. A journeyperson "will work under the supervision of a master."⁵ Your routes are the master license (two years as a licensed journeyperson, then the master exam, 75% to pass) or a company that employs a master as its master of record.⁴
• You do heating and air, not plumbing. Iowa's registration file puts "Plumbing/Heating & A/C" in one class, so a new registration under that name may be an HVAC shop. Same board, same contractor license, but your master has to hold a mechanical, HVAC-refrigeration or hydronic master license.⁵ And under Iowa law a water heater is plumbing, not HVAC.¹
• You do both. One contractor license, with a master in each discipline. That can be one person holding both master licenses, and two or more licenses bought for the same person on the same day get 30% off the license fees.^4,5
• You're a handyman, a GC or a drain cleaner without a plumbing license. Plumbing for pay needs the license. Chapter 105's "routine maintenance" exemption covers only rental property owners and their own employees, so a handyman swapping a water heater or a faucet for a customer isn't covered.¹ Sub the plumbing out to a licensed contractor. Drain cleaning is a gray area, covered below.

Iowa Plumbing and Mechanical Systems Board license types and what each covers

The board's licenses run on one statewide three-year term. All of them expire June 30 every three years, starting June 30, 2026, so a license you get now runs to June 30, 2029, and its fee is cut by one sixth for each six months of the term already gone.^1,4

Sources for the table: chapter 105,¹ the board's fee and licensure rules,⁴ the practice rules,⁵ DIAL's contractor and fee pages.⁸

What does "plumbing" cover? The statute's list is long: water supply and distribution piping, fixtures and traps, drain and vent piping, building drains and building sewers, storm drains "within the property lines of the premises," the connections to the sewer and water mains, and "potable water treating or using equipment, medical gas piping systems, fuel gas piping, water heaters and vents."¹ So water heaters, softeners and gas piping are all plumbing in Iowa. There's no residential or commercial class and no dollar limit in chapter 105 or the board's rules: a $200 faucet and a hospital are the same license.^1,5 And it works in every Iowa city. State licensing "shall supersede and preempt" local plumbing licensing, so a city can charge permit and inspection fees but can't make you take its own plumbing exam.¹

Who must hold what: the master of record

Iowa ties the business to a person. A plumbing business needs "at all times a licensed master ... employed by the person and ... actively in charge" of its plumbing work, and a sole proprietor "shall be a licensed master in the applicable discipline."¹ The board calls that person the master of record.⁵ Four rules follow from it:

• No ownership share is required. The contractor can hold the master license or "employ at least one person holding a master license." An LLC owned by a journeyperson can be a licensed contractor if it employs a master who's really in charge.¹
• One company per discipline. "A master may only be a master of record for one contractor in any particular discipline at any one time," unless the board approves it in advance. A master plumber who also holds a mechanical master license can be master of record for a plumbing company and a different HVAC company.⁵
• Six months if the master leaves. If your master quits, is fired or lets the license lapse, you can keep working for up to six months without a new one, but only if you tell the board within 30 days. DIAL takes the notice through its online contact form (company name, license number, date the relationship ended), and a new master goes in on the Master of Record Certification Form.^5,8
• The master has duties too. A master of record who leaves has to tell the board and the company within 30 days, and must not do licensed work for an unlicensed contractor.⁵

If someone has asked you to be their master of record, read the definition first: you're the one "responsible for the proper designing, installing, and repairing" of the company's plumbing and "actively in charge" of it.⁵ The board can discipline a licensee for "permitting another person to use the licensee's ... license number for any purpose" and for aiding unlicensed work, with civil penalties up to $5,000.⁷ A Colorado owner described the version that goes wrong: "Most hire a master plumber in name only to pull permits" (Reddit). In Iowa you can carry only one plumbing company at a time, so price it as a real job, not a signature.

Who supervises whom: the new 3-to-1 apprentice ratio

This changed in 2026. Senate File 2168, signed June 2, 2026 and in force since July 1, added a ratio to chapter 105: "A licensed journeyperson or master may employ or supervise licensed apprentices at a ratio not to exceed three apprentices to one licensee." Classroom training doesn't count against it.²

• Apprentices need an apprentice license ($50) and a spot in a registered apprenticeship, and they work only under a master or journeyperson who is "also employed by the contractor" and licensed in that discipline.^1,5 An apprentice never runs a job alone.
• Journeypersons work under a master's supervision, and the master has to "be available to supervise journeypersons or apprentices as needed."⁵ The rules don't say the master must stand on the job site, so in my reading a journeyperson can run a service call alone if a master is supervising and reachable.
• Helpers need no license for "general manual labor" while assisting a licensee, but their hours don't count toward a journeyperson license and the licensee answers for their work.^1,5 A helper who solders, glues or sets fixtures is doing licensed work.
• Cities add their own on-site rules. Iowa City wants a licensed person "present at all locations and at all times" when licensed work is going on, one for every three laborers, employed by the permit holder. Davenport wants plumbing done "by or under the direct supervision of an individual licensed as a journeyman who is employed by the licensed contractor."^17,18

Where your Iowa plumbing license stops

• Furnaces, boilers and air conditioning. That's mechanical work: HVAC, refrigeration and hydronic, and a boiler is hydronic. Gas piping is in your license ("fuel gas piping"), so you can run the gas line; setting, venting and starting up the furnace or boiler needs a mechanical, HVAC-refrigeration or hydronic license and a master of record in that discipline.^1,5 Going the other way, an HVAC shop can't swap a water heater: it's plumbing.¹
• The water heater circuit and the sump pump. Wiring for someone else needs an electrical license. Chapter 103 exempts "routine maintenance," the replacement of existing electrical equipment "of the same size and type for which no changes in wiring are made," and plugging an appliance into an existing supply.¹² My reading: reconnecting a like-for-like electric water heater to the same circuit, or plugging a new sump pump into the existing receptacle, is fine. A new circuit, a bigger breaker, an electric tankless or a heat pump water heater that needs its own circuit goes to an electrician. More in Iowa electrical license.
• Backflow testing and repair. A separate DIAL registration. "A person shall not test or repair backflow prevention assemblies without first having registered," and that covers repairs, not only the annual test.¹⁰ It takes a 32-hour course (or ABPA or ASSE certification), costs $72 for two years, and renews with a five-hour course. Breaking the rule is a simple misdemeanor.¹⁰
• Fire sprinklers. Chapter 100D requires a fire protection system license to install or maintain sprinkler systems. It exempts a plumber "working within the scope of the person's license," but Iowa's plumbing code deletes the UPC's residential fire sprinkler section, so in my reading sprinklers aren't plumbing scope. Sub them out.^3,11
• Medical gas. Needs NITC certification and the board's medical gas certificate ($75), plumbing license or not.^1,4
• Wells and propane. Certified well contractors working on a well, well pump and its water system, and people qualified under the state's LP gas rules working on propane equipment and piping, don't need a plumbing license for that work.¹ They're legal competition on those jobs, and good subs.
• Septic. Your license covers the building sewer within the property lines. I didn't research septic installer rules for this page; call the county environmental health office before you quote one.
• Drain cleaning. Chapter 105 doesn't mention it, and I found no board guidance. Running a cable through an existing cleanout isn't obviously "installing or repairing plumbing," but pulling a toilet, cutting in a cleanout or replacing pipe is. If you're a drain-only company without a license, ask the board in writing before you advertise. Des Moines needs no permit for "the removal of stoppage in sewer or waste pipes."^1,14
• Lead paint in pre-1978 homes. Iowa runs its own lead-safe renovation program through DIAL. The small-job exemption names plumbing, but only while you disturb less than 6 square feet of painted drywall or plaster per room (1 square foot of painted wood), and work in the same room within 30 days counts as one job. A small access hole behind a vanity is usually under it; opening walls for a repipe usually isn't. Above the line you need a certified renovator and a certified firm: $60 a year per person, firm certification free, up to $5,000 per violation.¹³

Iowa plumbing permits and inspections

Here's the part that surprises people coming from other states: the state of Iowa doesn't issue plumbing permits. The board's code rule says permit, inspection and enforcement provisions "are not administered by the Plumbing and Mechanical Systems Board or the state," and chapter 105 says cities don't have to inspect.^1,3 Cities that want a permit program run their own. The code still applies "in each local jurisdiction," and the board's rules make every licensee "apply for and obtain all applicable permits prior to performing any work."^1,5 Skipping a required permit is a ground for discipline.⁷ So: where a city issues permits, pull one first. Where nobody does, there's no permit to pull, but the job still has to meet the code, and your photos and invoice are the only record.

The big four: Des Moines, Cedar Rapids, Davenport, Iowa City

• Des Moines. Permits for "any installation, alteration, repair, replacement, or remodel," except maintenance "such as the repairing of leaks, the removal of stoppage in sewer or waste pipes, or the repairing of faucets and closet tanks." Only holders of a board contractor license get plumbing permits, and the contractor and every plumber on the job keep a copy of their license at the site.¹⁴ A plumbing permit for work on an existing house is $77.25 (2026 fees); a new house is $206.¹⁴ Digging in the street needs the city's excavation permit, which it issues only after the plumbing permit.¹⁴
• Cedar Rapids. "In order for contractors to perform work and be issued a permit in the City of Cedar Rapids, licensing with the State of Iowa is required." The permit holder books its own inspections by email, by 4:00 PM the business day before, for a morning or afternoon window, and plumbing inspections have to happen before the framing and final building inspections. The plumbing inspectors' line is 319-286-5832.¹⁶
• Davenport. A city license for plumbing contractors on top of the state one: no fee and no city exam, but a copy of your state license and a $5,000 surety bond on the city's own form, mailed in as an original.¹⁷ State law preempts local plumbing licensing, so I'd treat it as a registration, but the city expects it before you work there.¹
• Iowa City. "Only Master electricians, Master plumbers, and Master HVAC contractors may pull permits," and nobody may "plan for, lay out, supervise or perform plumbing work within the City" without a state master plumber license, outside the homeowner permit. Sewer and water service lines need the city's installer license or a state journeyperson or master plumbing license.¹⁸

I didn't check every town. Call the building department before the first job in a new city and ask two things: do you issue plumbing permits, and what does a water heater swap need?

The water heater swap in Des Moines

Des Moines publishes its list, and it's a good model for what an inspector looks at anywhere the UPC applies. The permit comes first; a homeowner can pull one for their own house, "otherwise a STATE licensed plumbing/ mechanical contractor is required." Book the final inspection at least 24 hours ahead (515-283-4200). The sheet asks for a cold water shutoff serving only the water heater, rigid pipe for the relief valve discharge ("NO PVC or plastic pipe"), a black iron gas drop ("No CSST ... or flex gas line piping shall be used as a gas drop to the water heater"), bonding of any existing unbonded CSST "at this time," and 50 cubic feet of combustion air per 1,000 Btu. For a tankless unit it warns that the gas pipe may need upsizing.¹⁴ Price those items into the quote before you're standing in the basement.

Which code: the Iowa plumbing code is the 2024 UPC

Iowa adopted the 2024 Uniform Plumbing Code with its own amendments, effective March 26, 2025. "Local jurisdictions may not adopt other plumbing codes," though they can adopt stricter amendments and send them to the board.³ A few of the amendments you'll meet on house jobs: building supply piping at least 60 inches deep, only CSST with an arc-resistant jacket, a dishwasher air gap or a high loop on the discharge, and fuel gas piping under UPC chapter 12 unless the state's LP gas rules say otherwise.³ The "Iowa plumbing code" hours in your continuing education are on this one.⁶

Backflow and the water utility

Every city of 15,000 or more has to run a backflow program with containment. Before anyone installs or rebuilds a water service, the city or water utility rates the hazard; it can then require an assembly right after the meter (an air gap or reduced pressure assembly for high hazard, a double check for low hazard) and can shut off water to a customer who refuses.³ In Des Moines that's Des Moines Water Works, which runs the cross-connection program with its own tester list and test form (515-283-8775).^14,15 If you'll test or repair assemblies, get the DIAL tester registration first and ask each utility how it wants the reports.¹⁰

The homeowner exemption

An owner can do plumbing on their own principal residence if it's an existing single-family home (not new construction) that qualifies for the homestead tax credit, and unpaid volunteers helping them need no license either.¹ DIAL reminds owners that "local jurisdictions may still have permit or inspection requirements."⁸ Rentals, new houses and anything you're paid for are outside it.

Can I take this job? An Iowa table

The verdicts assume your company holds the contractor license with a master plumber of record, the house is an existing single-family home, and it was built after 1978 unless the row says otherwise. "With a permit" means where the city issues one, because the state doesn't. If you hold only the registration, every row is "sub it out."

Sources for the table: chapter 105,¹ the plumbing code rule,³ the practice rules,⁵ backflow,¹⁰ chapter 100D,¹¹ chapter 103,¹² lead,¹³ the city codes and pages.^14,16,17,18

Your first 30 days: the Iowa plumbing contractor checklist

This is the whole list. The printable version is the same items with tick boxes and blanks for the numbers permit counters, water utilities and general contractors ask for.

Week 1: the credentials

1. Pick the business entity. Sole proprietor, or an LLC formed by filing a certificate of organization with the Iowa Secretary of State through Fast Track Filing.¹⁹ A sole proprietor has to be the master and carries the insurance and bond personally; an LLC carries them in its own name.¹
2. Find out which registration you have. Note your C number. If it came from the joint application, it renews with the contractor license. If it came from DIAL's stand-alone $50 registration, it renews every year and you still need the license.⁹ Look your company up on the board's public license search.⁸
3. Get the unemployment insurance number from Iowa Workforce Development, even with no employees. The application asks for it.⁸
4. Buy the $5,000 surety bond. It's a performance bond: the obligee is your customers ("licensee's Iowa customers" is wording DIAL has accepted), never the state or the board, and the surety has to give the board 10 days' notice before cancelling it.^5,8 Out-of-state contractors also file a $25,000 bond with the registration.⁸
5. Put $500,000 of public liability insurance in force. The certificate goes to the board with the certificate holder listed as "Bureau of Environmental Health & Contractor, Iowa Dept of Inspections, Appeals & Licensing, 6200 Park Ave Ste 100, Des Moines, IA 50321," and 10 days' cancellation notice to the board.⁸
6. Workers' comp before your first employee starts. The application needs a certificate listing DIAL as certificate holder once you have one or more employees.⁸
7. Apply for the contractor license on DIAL's license portal (the joint application), naming your master of record. $400 between July 1 and December 31, 2026, plus $25 if you file on paper.⁸ Don't book plumbing jobs until the license is issued.
8. License your crew. Apprentice licenses ($50) for anyone in a registered apprenticeship, no more than three per journeyperson or master; journeyperson licenses ($180). Helpers stick to manual labor.^1,2,4

Week 2: permits, cities and the water utility

9. Make a list of the towns you'll work in and call each building department: do they issue plumbing permits, how do you book inspections, and what does a water heater swap need?
10. Des Moines: ask the Permit and Development Center (515-283-4200) how it wants you to apply, save the water heater requirements sheet, and keep a copy of every plumber's license in the truck.¹⁴
11. Cedar Rapids: save the inspection request address (InspectionRequests@cedar-rapids.org) and the 4:00 PM cutoff the business day before.¹⁶
12. Davenport: send the city license application, a copy of your state license and the original $5,000 bond on the city's form.¹⁷
13. Iowa City: make sure a master plumber pulls the permits and a licensed person is on every job.¹⁸
14. Water utilities: find out who runs the backflow program for each city of 15,000 or more you'll work in (Des Moines Water Works in Des Moines) and save their tester list and test form. If you'll test or repair assemblies, take the 32-hour course and register with DIAL ($72 for two years).^3,10,15

Weeks 3 and 4: paperwork and habits

15. Put your contractor license number on every written ad. That one is the law: "All written advertisements distributed in this state" by a plumbing business "shall include the listing of the contractor license number."¹ I'd treat the website, flyers, door hangers and truck as ads. Put the license number, master's name and C number on every quote, invoice and contract too.
16. Hang the contractor license certificate where you do business, and carry a copy of each plumber's license at the job site.^1,5
17. Make permits a habit. A permit line on every quote that needs one, the permit pulled before you start, and inspections booked by whoever pulled the permit.^5,16
18. Line up subs for what your license doesn't cover: an electrician for new circuits, an HVAC contractor for furnaces and boilers (unless you hold that license too), a fire protection contractor for sprinklers, a registered backflow tester if you aren't one.
19. Lead-safe certification if you'll open walls in pre-1978 homes: an Iowa lead-safe renovator ($60 a year) and a certified firm (free).¹³
20. Put the dates on the calendar. Licenses expire June 30, 2029; renewal opens May 1, 2029. Continuing education by then: 8 hours for a plumbing license (2 safety, 2 plumbing code, 4 plumbing), up to half online. Late fees: $60 from August 1, $100 from September 1, when you also have to stop working.^4,6,8 Insurance and bond renewals. Backflow registration every two years.
21. Know what to report. A new business address within 30 days; losing your master of record within 30 days (that starts the six-month clock); and any judgment or settlement of a claim related to your plumbing work within 30 days.^5,7

What happens if you cross the line

Plumbing without the license

• A civil penalty of up to $5,000 per offense, and "each day of a continued violation constitutes a separate offense," though offenses from "the same or common facts or circumstances" count as one.¹ The board's list of unlicensed practices includes "providing plumbing ... services on a contractual basis" and running a plumbing business "without employing a licensed master."⁷
• An injunction, and the board can refer the case for criminal prosecution.^1,7
• Claiming to be licensed when you aren't, or listing someone else's license number in an ad, is a simple misdemeanor: a fine of $105 to $855 and up to 30 days in jail.^1,20
• Without the registration: DIAL citations of up to $500 for a first violation and up to $5,000 after that.⁹

If you hold a license

• The board can revoke, suspend, put you on probation or fine you up to $5,000. Grounds include contracting "without a board-issued contractor license," working as a contractor "without valid bonding or insurance," skipping a required permit, letting someone use your license, and letting an unlicensed employee do licensed work.⁷
• Your master and journeypersons are exposed too: none of them may knowingly work for an unlicensed contractor.⁵

Backflow without registration

A simple misdemeanor, and DIAL can order you to stop testing or repairing assemblies.¹⁰

Getting paid and insurance

Chapter 105 doesn't say a contract for unlicensed plumbing is void, and I didn't research Iowa case law on whether a court would enforce one. Iowa's lien law says a 91C registration "shall not be required in order to post a notice or a lien," but it says nothing about the plumbing license.²⁰ Don't be the test case. On insurance, the rule is that the $500,000 policy and the bond must be in force for the whole license period, and the insurer has to warn the board before cancelling.⁵ I found no Iowa rule on what unlicensed or out-of-scope work does to a claim. That's in your policy, so ask your agent in writing: "Does my policy cover work outside the license I hold?" Keep the reply.

More for new plumbing contractors

• How much to charge per hour: service call minimum, first hour and flat prices, with a free rate sheet.
• Water heater replacement checklist: the code items, the permit and what to charge, with a free printable.
• You got your master plumber license. Now what? Stay for a raise or start your own plumbing business, with the numbers for each.
• Asked to be the master of record: what being a company's plumbing qualifier pays, and what it can cost you.

Where Deepsel fits

Deepsel is the field service software I build, and it doesn't know Iowa law. It won't pull a permit, book an inspection, track your continuing education or warn you before the bond or the insurance lapses. What it does help with: the shop-wide terms text you set once is copied onto every quote and shows on the customer's quote page, and the invoice footer is copied onto every invoice, so your contractor license number, master's name and C number go on every document without retyping. You can attach a checklist to a quote (a water heater swap list with the permit number and the inspection date, say); it stays internal and editable after the customer approves. Files attached to a quote, like the permit, carry over to the job, and techs add photos to each visit. Each customer's equipment records hold the brand, model, serial number, year, fuel, gallons, venting, location and photos, so the water heater you installed is on file when the customer calls in eight years. Quotes can carry options, the customer approves and signs on screen, and an optional card deposit is credited on the final invoice. Free covers 30 estimates and 30 invoices a month for your whole team, with scheduling and dispatch, quotes, invoicing, card payments, and customer and equipment records; Pro is $29 a month with unlimited estimates and invoices (pricing).

Frequently asked questions

Do you need a plumbing license to run a plumbing business in Iowa?

Yes. Iowa Code chapter 105 says nobody may 'operate as a contractor or install or repair plumbing' without a license from the Plumbing and Mechanical Systems Board. The business needs a contractor license, and it needs a licensed master plumber who is employed by it and 'actively in charge' of the plumbing work at all times. If you run it as a sole proprietor, you have to be that master yourself. The DIAL contractor registration (your C number) is a separate thing and doesn't license any plumbing work on its own.

How do I get a plumbing contractor license in Iowa?

Apply to the Plumbing and Mechanical Systems Board on DIAL's license portal, using the joint application that also issues your contractor registration. You need a master plumber of record (you, or an employee who isn't master of record for another plumbing contractor), $500,000 of public liability insurance, a $5,000 surety bond, a permanent place of business, an Iowa unemployment insurance number (even with no employees) and proof of workers' comp if you have employees. The insurance certificate and the bond both have to promise 10 days' notice to the board before they're cancelled. Applied for between July 1 and December 31, 2026, it costs $400: $250 for the license and $150 for three years of registration.

How much does an Iowa plumbing license cost?

For a full three-year term: $50 for an apprentice, $180 for a journeyperson, $240 for a master and $250 for the contractor license, plus $150 for the contractor registration that comes with it. The exam application is $35, and the testing company charges its own fee. A paper application adds $25. New licenses are prorated by one sixth for each six months already gone from the current term, and two or more journeyperson, master or contractor licenses bought together for the same person get 30% off the license fees.

How do I look up an Iowa plumbing license?

DIAL's contractor license page links to a public portal where you can search or verify plumbing and mechanical licenses online. Check the status of anyone you hire, and of any company before you sign on as its master of record. The contractor registration (the C number) is a separate search on DIAL's contractor registration portal, and a C number without a plumbing contractor license doesn't make a business a licensed plumbing contractor.

When does my Iowa plumbing license expire, and how do I renew it?

Every Plumbing and Mechanical Systems Board license expires on the same date, June 30, once every three years. The last one was June 30, 2026, so a license issued now runs to June 30, 2029. Renewal opens May 1 of the third year. Masters and journeypersons need at least 8 hours of board-approved continuing education per term: for a single plumbing license that's 2 hours of Iowa OSHA safety, 2 hours on the Iowa plumbing code and 4 hours of plumbing, and up to half can be online. Renew by July 31 with no late fee; in August it's $60 and you can still work; from September 1 it's $100 and you can't work until it's renewed.

What is the Iowa plumbing code?

The 2024 Uniform Plumbing Code with Iowa's amendments, in effect since March 26, 2025 (481 IAC chapter 425). It applies everywhere in Iowa. A city can't adopt a different plumbing code, but it can adopt stricter amendments and has to send them to the board. Iowa's amendments include a 60-inch minimum cover on building supply piping, arc-resistant jacketed CSST only, and deleting the UPC's residential fire sprinkler section. The state itself doesn't issue plumbing permits or inspect: cities that want a permit program run their own.

How do I get an HVAC or mechanical license in Iowa?

From the same board. Start as a licensed apprentice in a registered apprenticeship, finish four years, pass the journeyperson exam, then after two years as a journeyperson you can sit for the master exam (75% passes). A mechanical license covers HVAC, refrigeration, sheet metal and hydronic work; the HVAC-refrigeration and hydronic licenses each cover part of that. To contract, the business also needs the contractor license with a master in each discipline it works in. A water heater is plumbing under Iowa law, so an HVAC-only shop needs a plumber for water heater swaps.

What does the Iowa Plumbing and Mechanical Systems Board do?

It licenses plumbers, mechanical professionals and plumbing and mechanical contractors, adopts the state plumbing and mechanical codes, approves continuing education, and disciplines licensees. It can fine an unlicensed person up to $5,000 per offense, with each day a separate offense, and suspend or revoke a license. It sits within DIAL at 6200 Park Avenue, Suite 100, Des Moines; the board office line is 866-280-1521.

Can a homeowner do their own plumbing in Iowa?

Yes, on their own principal residence, if it's an existing single-family home (not new construction) that qualifies for the homestead tax credit, and volunteers helping them for free don't need a license either. Local permits still apply where the city has a program: Des Moines lets homeowners take out their own water heater permit, and Iowa City issues a homeowner plumbing permit to someone who shows the building official they can do the work.

Sources

1. Iowa Code chapter 105, Plumbers, Mechanical Professionals, and Contractors: 105.2 (definitions: HVAC and hydronic include their gas lines; "plumbing" includes "potable water treating or using equipment, medical gas piping systems, fuel gas piping, water heaters and vents"; routine maintenance), 105.4 (state plumbing code applies "in each local jurisdiction"; local jurisdictions not required to inspect), 105.9 (fees, 30% combined-license reduction, three-year terms, prorating), 105.10 (license required to "operate as a contractor or install or repair plumbing"; a master "employed by the person and ... actively in charge"; sole proprietor must be a master), 105.11 (exemptions: homeowner, LP gas, well contractors, helpers, right-of-way pipe, rental owners' routine maintenance, volunteers), 105.14 (display of contractor license), 105.17 (state licensing preempts local plumbing licensing; permit and inspection fees allowed), 105.18 (license types; contractor license: workers' comp, unemployment insurance, permanent place of business, "hold a master license or employ at least one person holding a master license"), 105.19 (insurance and bond by board rule; 10 days' notice), 105.20 (three-year terms; at least 8 hours of continuing education), 105.22 (discipline), 105.25 (written ads must list the contractor license number; false claims a simple misdemeanor), 105.26 (injunction), 105.27 (civil penalty up to $5,000 per offense, each day separate). legis.iowa.gov, Iowa Code 2026, read November 3, 2026.
2. Senate File 2168 (2026), Division II, new Iowa Code 105.18(5): "A licensed journeyperson or master may employ or supervise licensed apprentices at a ratio not to exceed three apprentices to one licensee"; signed June 2, 2026 (Acts chapter 1155), effective July 1, 2026. enrolled bill, bill history. Also checked: House File 2800 (2026) makes no change to chapter 105, legis.iowa.gov. Read November 3, 2026.
3. Iowa Administrative Code 481, chapter 425, State Plumbing Code (IAC 9/30/26): 425.1 (2024 Uniform Plumbing Code adopted with amendments, effective March 26, 2025), 425.2 ("Local jurisdictions may not adopt other plumbing codes"), 425.3 (fuel gas piping), 425.4 (amendments, including 101.2: permit, inspection, testing and enforcement provisions "are not administered by the Plumbing and Mechanical Systems Board or the state"; 609.1 supply piping 60 inches deep; 612 residential fire sprinklers deleted; 807.3 dishwasher discharge; 1208.5.3.5 arc-resistant CSST), 425.5 (backflow prevention with containment in cities of 15,000 or more). legis.iowa.gov, read November 3, 2026.
4. Iowa Administrative Code 481, chapter 428, Licensure Fees (apprentice $50, journeyperson $180, master $240, medical gas $75, contractor $250, specialty $50; exam application $35; late fees $60 and $100; paper application $25; combined-license 30% reduction), and chapter 429, Application, Licensure, and Examination (disconnect/reconnect plumbing technician specialty; masters need two years as a journeyperson; medical gas certification through NITC; 75% passes; licenses "expire on June 30 every three years, beginning with June 30, 2026"; contractor renewal "constitutes registration as a contractor"; one-month grace, valid two months past expiration). 428, 429, read November 3, 2026.
5. Iowa Administrative Code 481, chapter 431, Licensee Practice: 431.1 ("master of record"), 431.2 (license copy at the work site; "apply for and obtain all applicable permits prior to performing any work"; responsibility for helpers), 431.3 (contractor: a master for each discipline, not one "simultaneously associated with another contractor in that discipline"; six-month grace period with notice within 30 days; surety bond "in a minimum amount of $5,000"; public liability insurance "in a minimum amount of $500,000"; permanent place of business; apprentices supervised by a master or journeyperson "also employed by the contractor"), 431.4 (one contractor per discipline per master; master "available to supervise"; 30-day notice on leaving), 431.5 (journeyperson "will work under the supervision of a master"), 431.6 (apprentices), 431.7 (specialty licenses). legis.iowa.gov, read November 3, 2026.
6. Iowa Administrative Code 481, chapter 432, Continuing Education (the "Iowa plumbing code" is the UPC as adopted by the board; 2 hours safety, 2 hours code and 4 hours discipline per term for a single license; up to half online). legis.iowa.gov, read November 3, 2026.
7. Iowa Administrative Code 481, chapter 434, Licensee Discipline: 434.2 (grounds, including letting another use your license number, failing to report a judgment or settlement within 30 days, permitting unlicensed employees, failing to obtain a required permit, "contracting for plumbing or mechanical work in the state of Iowa without a board-issued contractor license," "practicing as a contractor without valid bonding or insurance"), 434.3 (sanctions, civil penalties up to $5,000), 434.5 (civil penalties against unlicensed persons; referral for criminal prosecution). legis.iowa.gov, read November 3, 2026.
8. DIAL, Plumbing and Mechanical Systems Board pages: "Contractor License" (definition of contractor; $500,000 public liability insurance; certificate holder address; $5,000 surety bond, obligee not the state or the board; master of record rules and certification form; joint application with registration; unemployment insurance number "even if you have no employees"; workers' comp with one or more employees; out-of-state $25,000 bond; public license search), "Licensing Period & Fees" ("Jul. 1 - Dec. 31 (Year 1) ... $400.00 ($250 + $150)"; renewal opens May 1 of year three; late fees and eligibility to work), and "Plumbing & Mechanical Systems Licensure" (8 hours of continuing education; volunteer work; 866-280-1521). contractor license, fees, licensure, license portal, public license search, read November 3, 2026.
9. Iowa Code chapter 91C, Construction Contractors (91C.1 $2,000 threshold; 91C.2 workers' comp evidence and unemployment insurance account; 91C.8 penalties up to $500, then up to $5,000), legis.iowa.gov; Iowa Administrative Code 481-465 (number is "C" and six digits), legis.iowa.gov; DIAL, "Contractor Registration" ($50; renewed every year; plumbing businesses use the joint application for "a 3-year registration and contractor license"; penalties), dial.iowa.gov. Read November 3, 2026.
10. Iowa Code chapter 135K, Backflow Prevention Assembly Testers (135K.3 registration required to "test or repair backflow prevention assemblies"; 135K.5 simple misdemeanor; 135K.6 orders to stop), legis.iowa.gov; Iowa Administrative Code 481-476 (476.2; 32-hour course), legis.iowa.gov; DIAL, "Backflow Prevention Assembly Tester Registration" (course or ABPA/ASSE certification; $72; two years; five-hour renewal course), dial.iowa.gov. Read November 3, 2026.
11. Iowa Code chapter 100D, Fire Protection System Installers and Maintenance Workers: 100D.2 (license required), 100D.11(3) (exemption for a chapter 105 plumber "working within the scope of the person's license"). legis.iowa.gov, read November 3, 2026.
12. Iowa Code chapter 103, Electricians and Electrical Contractors: 103.1(18) ("routine maintenance": same size and type, "no changes in wiring"), 103.11 (license to wire for another), 103.22(6) (no license to engage "any electrical appliance where approved electrical supply is already installed"), 103.22(12) (routine maintenance). legis.iowa.gov, read November 3, 2026.
13. Iowa Code 10A.902 (lead-safe renovator certification; civil penalty "not to exceed five thousand dollars for each offense"), legis.iowa.gov; Iowa Administrative Code 481-470 ("minor repair and maintenance activities," "including ... plumbing"; under 1 sq ft of painted wood, 6 sq ft of drywall or plaster per room, 20 sq ft outside; same room within 30 days is one project; housing built before 1978), legis.iowa.gov; DIAL, "Lead Safe Renovation and Prerenovation Notification" ($60 a year per individual; firm certification free), dial.iowa.gov. Read November 3, 2026.
14. City of Des Moines: Municipal Code chapter 26 (2023 updates, markup version), 26-606 (permits "for any installation, alteration, repair, replacement, or remodel"; excavation permits after plumbing permits), 26-607 (maintenance exceptions), 26-608 (license copies at the premises), 26-628 (Des Moines Water Works and the building official run backflow containment), 26-670 (permits only to holders of a board contractor license), 26-671 (state licensees recognized), cms2.revize.com; Permit and Development Center Permit Fees, new fees 1-1-26 ($77.25 for plumbing on an existing dwelling, $206.00 for a new dwelling), fee schedule; "Water Heater Installation Requirements," requirements sheet. Read November 3, 2026.
15. Des Moines Water Works, "Backflow Prevention" (cross-connection control program; backflow tester list and test form; 515-283-8775). dmww.com, read November 3, 2026.
16. City of Cedar Rapids, "Licensing for Contractors" and "Inspection Requests" (state licensing required for a permit; permit holder schedules inspections by 4:00 PM the business day before; trade inspections before framing and final; Plumbing Code 319-286-5832). cedar-rapids.org, cedar-rapids.org, read November 3, 2026.
17. City of Davenport, "Contractor Licenses" (plumbing "by or under the direct supervision of an individual licensed as a journeyman who is employed by the licensed contractor"; electrical, HVAC and plumbing licenses: state licensing and testing, no fee, copy of state license, $5,000 bond) and "Contractor Bond and Bond Instructions" ("Electrical, Mechanical, Plumbing and Sign Contractors shall furnish a bond in the sum of $5,000"; city bond form, original mailed). davenportiowa.com, davenportiowa.com, read November 3, 2026.
18. City of Iowa City, "Licensing Requirements" (only master plumbers pull plumbing permits; master plumber license to plan, lay out, supervise or perform plumbing work; licensed person present at all times, one per three laborers; homeowner plumbing permits; sewer and water service installer license or state plumbing license). icgov.org, read November 3, 2026.
19. Iowa Secretary of State, Fast Track Filing Resource Center, "How do I form an Iowa Limited Liability Company (LLC)?" help.sos.iowa.gov, read November 3, 2026.
20. Iowa Code 572.34(11) ("Registration under chapter 91C shall not be required in order to post a notice or a lien under this chapter"), legis.iowa.gov; Iowa Code 903.1(1)(a) (simple misdemeanor: fine of $105 to $855, up to 30 days), legis.iowa.gov. Read November 3, 2026.