Licensed Plumber in Maryland: How to Verify Before You Hire

Maryland licenses plumbers through the Maryland State Board of Plumbing, a state agency that issues Master Plumber and Journeyman Plumber credentials and enforces licensing standards statewide. For residential home improvement plumbing work, the contracting business must also hold an MHIC license through the Department of Labor, Licensing and Regulation. Together these two layers of licensing provide meaningful consumer protections — but only if you verify them before you hire.

This guide covers Maryland plumber license types, how to search the DLLR database, what bond requirements apply, and the real cost of hiring an unlicensed plumber in Maryland.

Does Maryland require plumbers to be licensed?

Yes. Maryland requires plumbers to hold a license from the Maryland State Board of Plumbing, which operates under the Department of Labor, Licensing and Regulation at dllr.state.md.us. Maryland issues two individual plumbing credentials: Master Plumber and Journeyman Plumber. For residential plumbing work on home improvement projects, the contracting business must also hold an MHIC license from the Maryland Home Improvement Commission.

A Master Plumber is licensed to supervise plumbing work, pull permits, and operate a plumbing contracting business. A Journeyman Plumber is licensed to perform plumbing installations under the supervision of a Master Plumber. Unlicensed individuals may assist but cannot independently perform plumbing work that requires a license.

These requirements apply across Maryland with no county-level exemptions at the state credential level. Local permit requirements may layer on top of state licensing, and some jurisdictions — including Montgomery County — have historically maintained active local inspection programs in addition to state requirements.

Where do I verify a plumber's license in Maryland?

Search the Maryland DLLR plumber license lookup at dllr.state.md.us/license/plumber. Enter the plumber's name or license number. Results show the license type (Master or Journeyman), current status, and expiration date. For plumbing businesses performing residential home improvement work, also verify their MHIC license at dllr.state.md.us/license/mhic.

When verifying, search the individual plumber's name and the company name separately. The Master Plumber overseeing the work should have a searchable individual license, separate from any business registration. If a plumber cannot provide their license number when asked, treat that as a significant warning sign.

The Board of Plumbing database also reflects disciplinary history. License suspensions, revocations, and formal complaints are recorded. Reviewing this history takes less than a minute and reveals whether the plumber has had enforcement action taken against them in the past.

What are the plumber license types in Maryland?

Maryland issues two primary plumbing credentials. A Master Plumber has passed a comprehensive exam covering the Maryland Plumbing Code, the Uniform Plumbing Code, and business law, and is authorized to supervise all plumbing work, pull permits, and operate a plumbing contracting business. A Journeyman Plumber has passed a trade-level exam and may perform plumbing work under the direct supervision of a Master Plumber.

When hiring a plumbing company, the Master Plumber is the license holder responsible for the installation. They must pull the permit. If a plumbing company tells you they do not need a permit for a significant plumbing job — water heater replacement, drain line work, fixture installation involving new supply or drain lines — that is a red flag.

Plumbing apprentices may assist on job sites but may not perform licensed work independently. A crew working without a licensed Master Plumber on the project is not a compliant installation regardless of experience or years in the trade.

What bond and insurance should a Maryland plumber carry?

Maryland MHIC-licensed plumbing contractors are required to carry a $20,000 surety bond as part of MHIC licensing. The bond provides homeowner protection if the contractor fails to complete work, abandons the project, or causes harm they refuse to cover. Plumbing contractors must also carry general liability insurance and workers' compensation for employees. Verify both by requesting certificates of insurance and calling the issuing carrier to confirm the policies are active.

The MHIC's Home Improvement Guaranty Fund provides an additional layer of protection — up to $20,000 per project for claims against licensed contractors who default or disappear. If the plumber you hire is not MHIC-licensed, neither the bond nor the Guaranty Fund applies. This is precisely why verifying licensure before signing a contract matters.

What are the penalties for unlicensed plumbing in Maryland?

Maryland imposes fines of up to $5,000 for a first offense of performing home improvement plumbing work without an MHIC license, and up to $10,000 for each subsequent offense. The Board of Plumbing may separately penalize individuals who perform or supervise plumbing work without the required Master or Journeyman credential. Contracts with unlicensed plumbers may be unenforceable in Maryland courts, potentially allowing homeowners to void agreements and recover payments.

Unpermitted plumbing creates serious downstream risk. Insurance carriers frequently deny water damage claims when the damage resulted from unpermitted or unlicensed plumbing work. At sale, unpermitted plumbing must be disclosed and may require remediation. The Maryland Department of the Environment also has jurisdiction over backflow, septic, and water quality issues that arise from improperly installed plumbing systems.

What should I verify before hiring a plumber in Maryland?

Before any plumbing contractor begins work, verify the supervising Master Plumber's Maryland license number, confirm the company holds an MHIC license for residential home improvement work, ask for proof of general liability and workers' compensation insurance, and confirm permits will be pulled for any work beyond minor repairs. Any legitimate Maryland plumber will provide this information without hesitation.

Plumbing failures are among the most expensive home repair scenarios. According to the Insurance Information Institute, water damage and freezing claims are the second most common homeowner insurance claim type in the United States. Work performed by unlicensed plumbers is a leading contributor to preventable plumbing failures.

CheckLicensed.com can verify any Maryland plumber's license status instantly before work begins. Confirm the Master Plumber credential and the MHIC business license — both searches are quick and could save you from a costly and uninsured repair down the line.