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Hiring a Plumber in New Hampshire

Updated 2026-10-10 · 6 min read

How to hire a plumber or gas fitter in NH: license levels, gas fitter types, checking a license with OPLC, homeowner exemptions, permits and the code.

Plumbers and gas fitters are licensed in NH

New Hampshire licenses plumbers and fuel gas fitters through the Mechanical Licensing Board, part of the Office of Professional Licensure and Certification (OPLC). The rules are in the mechanical licensing section of RSA 153, starting at RSA 153:27. Plumbing and gas work are separate licenses, and many jobs, like a new gas water heater, can involve both. For an overview of every licensed trade, see which NH contractors need a license.

Plumber license levels

The board licenses plumbers at three levels. Here is how RSA 153:27 describes them:

Master plumber: a person or company that hires others to do plumbing as a business, or does plumbing for its own account.
Journeyman plumber: installs, maintains and repairs plumbing and drainage under the direction of a master plumber.
Apprentice plumber: is learning the trade in an apprenticeship program that meets board rules. A plumbing licensee can employ no more than 2 apprentices.
Companies: a business can hold a plumbing license if an officer or member (or a designee) holds an active master plumber license. Before a business license is issued or renewed, the company must show proof of good standing with the Secretary of State and proof of liability insurance (RSA 153:29-a).

Gas work needs a gas fitter license

Gas fitter licenses are split by the kind of work, and RSA 153:29 says no licensee may do work outside their specialty license. The types defined in RSA 153:27 are:

Fuel gas installation technician: installs inside and outside gas piping from the meter or first-stage regulator, and gas appliances and equipment, including heating and water heating systems.
Fuel gas service technician: services and repairs that same piping and equipment.
Fuel gas piping installer: installs propane or natural gas piping.
Domestic appliance technician: limited to home gas dryers, stovetops, ranges, outdoor cooking equipment and pool heaters, and their venting.
Hearth system installation and service technician: gas fireplaces and other hearth appliances and their venting.
Fuel gas trainee: working toward a license, under the direct supervision of a licensed gas fitter.

How to check a license

Use the free OPLC license lookup and choose "Mechanical" as the profession. Confirm the license is active (OPLC's status definitions explain the others), that the type fits your job, and that the name matches your estimate. State law also says a license must be available for inspection on request (RSA 153:29), so it's fair to ask to see it.

Don't be thrown if a gas fitter's license just says "Gas Fitter." OPLC is converting the old, broad gas fitter license into the specific types above, starting with licenses that expire in 2026, according to its notice to licensees. The license number stays the same. OPLC's oil heating technician license is voluntary, so an oil heat tech may not hold one.

Homeowner exemptions and other exceptions

RSA 153:36 sets out when a license isn't required. The ones homeowners ask about most:

Plumbing in your own home: a property owner can install, repair or replace plumbing in their own single-family detached home or townhouse, including new construction, and can make minor repairs on their own property. The plumbing must still meet the state plumbing code. This exemption does not cover gas work.
Gas work in your own home: the gas exemption is narrower. It covers only an existing single-family, stand-alone home that you own, live in and use as your primary residence. You still have to follow the technical standards and any code, permit and inspection requirements.
Heating and water heater installers: the plumbing license doesn't apply to plumbing done as part of installing heating, cooling, air conditioning or water heating systems, or water treatment systems and pools. That work still has to meet code. If the equipment runs on gas, the gas work still needs a licensed gas fitter unless the homeowner gas exemption applies.
Well pumps: NHDES says licensed plumbers and electricians can repair and service well pumps but need a Water Well Board pump installer license to install or replace one. See our well water guide.

Plumbing code, permits and inspections

The State Building Code includes the International Plumbing Code (IPC) with New Hampshire amendments. According to the NH Division of Fire Safety, the code moved to the 2024 IPC on July 1, 2026. Through December 31, 2026, permit applications can follow either the 2021 or 2024 codes. Starting January 1, 2027, they must follow the 2024 codes. Gas piping falls under NFPA 54, the National Fuel Gas Code, as adopted in the state fire code (RSA 153:27).

Under state law, plumbing stops at the first fitting outside the foundation wall or 5 feet of pipe from the building (RSA 153:27). Sewer lines and septic systems beyond that point follow other rules. See our septic guide.

Permits and inspections are handled by your city or town, and the board's rules can be enforced by the local building department (RSA 153:35). Ask your building department what it requires, and read our building permit guide. State inspectors appointed by the Department of Safety can also inspect plumbing and gas work and order violations corrected (RSA 153:34). OPLC's Mechanical Licensing Board page says to call the Department of Safety at (603) 271-2791 for help with an inspection or to report a safety concern.

Safety points worth knowing

If you smell gas: Liberty Utilities tells customers to leave right away, not to use electrical switches or appliances, not to smoke or light matches, and to call the utility's emergency number or 911 from a mobile phone or a neighbor's phone. If you use another gas or propane supplier, follow its instructions.
Carbon monoxide detectors: under RSA 153:10-a, a single-family home built or substantially rehabilitated after January 1, 2010 needs a CO detector if it has an attached garage or any appliance that burns solid, liquid or gas fuel. For those homes, adding an attached garage or a fuel-burning appliance later also triggers the requirement.
Backflow: if your home is on a public water system, NHDES rules require that system to guard against cross connections, and systems serving 1,000 or more people need a written program (NHDES). Your water department may require a backflow prevention device on some connections. Ask your plumber or water department.

Questions to ask before you hire

What are your license numbers, and do you hold the right plumbing or gas fitter license for this job?
Who will do the work, and will a master plumber be responsible for it?
Will you pull the plumbing and gas permits and schedule the inspections?
Can you send a certificate of insurance from your insurer? The NH Insurance Department notes that a licensed contractor isn't automatically insured.
What does the written estimate include, and what could change the price?

Red flags

No license number, or the lookup shows an expired or inactive license.
A plumber without a gas fitter license offering to run a gas line or hook up a gas appliance.
Asking you to pull the permit in your own name, which the NH Insurance Department lists as a warning sign.
Claiming the homeowner exemption covers them. It covers the owner's own home and has strict limits for gas.

Before you sign

Put the scope, price and who handles permits in writing. Our contractor hiring checklist covers contracts, deposits and red flags. OPLC takes complaints about licensees. Find licensed pros in our plumbers and HVAC listings.

This guide is general information, not legal advice. Laws, codes and local rules change, so confirm current requirements with OPLC and your town's building department.