Water Heater Replacement — Maryland license requirements

Verified 2026-10-058 official sources3 classification relations7 scope assertionsIndexation gate: passed

01 The project

The starting point is the work itself — Water Heater Replacement in Maryland. The job determines which trades are involved, and the trades determine which license classifications may be required.

No project components are seeded for this project — we do not invent component lists without evidence.

02 Jurisdiction

This project is evaluated for Maryland — the home-improvement licence state. There is no project-value general-contractor licence: the MHIC home improvement contractor licence (Business Regulation Art. Title 8) covers residential alteration/remodel/repair on 1–3 unit buildings, the trades are licensed individually (electrician BOP Title 6, plumber/gas fitter Title 12, HVACR BR Title 9A), and new-home construction is a Home Builder Registration. Maryland jurisdiction page.

Limitation — local permit fees are unread; no unconditional statewide bond

Local building and permit fees, and the electrician/plumbing/HVACR/Home-Builder licence fees, were not read — LOCAL_AUTHORITY_REQUIRED / NOT_VERIFIED. Maryland imposes no unconditional statewide surety bond on these credentials (an MHIC applicant who fails the solvency guidelines may buy a bond or obtain an indemnitor). State requirements are not the complete story for any locality.

03 Trade → license

Relations below are recorded per state — only this jurisdiction's classifications are shown.

Trades involved: no seeded components — trade resolution follows from the classification relations below.

May require MASTER-PLUMBER — Master Plumber (Gas Fitter) confirmed S-MD-BOP-12-101 rule MD-PLUMBING-LICENSE
Replacing a water heater is plumbing work (a plumbing appliance within a water-supply/drainage system) requiring a Maryland Board of Plumbing licence; gas-fired units invoke the natural-gas-fit side of the master plumber licence.
May require MASTER-ELECTRICIAN — Master Electrician confirmed S-MD-ELEC-MAIN rule MD-ELECTRICAL-LICENSE
CONDITIONAL — the electrical connection to a replacement water heater is electrical work requiring a licensed electrician (all electrical work must be performed by a licensed master, journeyperson or apprentice).
Alternative path HOME-IMPROVEMENT-CONTRACTOR — Home Improvement Contractor (MHIC) confirmed S-MD-BR-8-301 rule MD-MHIC-TRADE-EXEMPTION
Where the work is done by a licensed plumber/electrician acting within scope, the MHIC licence is not required (§8-301(c)(4)); if the replacement is sold as a broader home-improvement job, the MHIC licence applies.

04 Scope

What the official sources say about the work involved — typed assertions, never a boolean "covers". Interpretations are marked as such.

Officially excluded HOME-IMPROVEMENT-CONTRACTOR Construction Of A New Home (may_not_perform) Business Regulation §8-101(g)(3)(i) S-MD-BR-8-101
Officially excluded HOME-IMPROVEMENT-CONTRACTOR No Mhic License For A Licensed Electrician Plumber Hvacr Contractor Or Architect Acting Within Scope (requires) Business Regulation §8-301(c)(4) S-MD-BR-8-301
Officially excluded HOME-IMPROVEMENT-CONTRACTOR Subcontracting Home Improvement Work For An Mhic Licensed Contractor Without A License (may_perform) MHIC home page (subcontractor category eliminated) S-MD-MHIC-MAIN
Officially included MASTER-ELECTRICIAN Provide Electrical Services In All Aspects Of The Electrical Trade (may_perform) Business Occupations and Professions §6-101(g),(j); §6-605(b) S-MD-BOP-6-101
Officially included MASTER-PLUMBER Provide Plumbing Services And Natural Gas Services (may_perform) Business Occupations and Professions §12-101(l) S-MD-BOP-12-101
Officially excluded HOME-IMPROVEMENT-CONTRACTOR Work On Apartment Buildings With Four Or More Single Family Units Or Common Area Condominiums (may_not_perform) Business Regulation §8-101(g)(3)(v)-(vi) S-MD-BR-8-101
Officially included HOME-IMPROVEMENT-CONTRACTOR Act As A Contractor Performing Or Agreeing To Perform A Home Improvement For An Owner (may_perform) Business Regulation §8-301(a); §8-101(c),(g) S-MD-BR-8-301
The MHIC licence is a scope licence, not a project-value GC licence: it is the credential a homeowner's remodeler must hold.

05 Requirements

Requirement	Kind	Statement	Source
Plumbing and gas services require a Maryland Board of Plumbing licence (statewide, with carve-outs) Board overview + BOP §12-101 verbatim (read 2026-10-05)	license	Maryland State Board of Plumbing, verbatim: the Board 'licenses and regulates individuals who provide or assist in providing plumbing and gas services in Maryland.' The statutory licence classes (Business Occupations and Professions §12-101) are master plumber (providing plumbing AND natural gas services, including a master plumber gas fitter), journey plumber, apprentice plumber, limited master/journey plumber, master/journeyman/apprentice natural gas fitter, and a propane gas fitter certificate. State licences are required throughout Maryland EXCEPT Baltimore County and the WSSC area.	S-MD-PL-MAIN Source S-MD-PL-MAIN — Maryland State Board of Plumbing — Division of Occupational and Professional Licensing Maryland Board of Plumbing — overview and the Baltimore County / WSSC carve-out — Board overview + BOP §12-101 verbatim (read 2026-10-05) https://labor.maryland.gov/license/pl/ Retrieved 2026-10-05 · last verified 2026-10-05 State plumbing/gas-fitter licences are required statewide EXCEPT Baltimore County and the WSSC area (Prince George's & Montgomery Counties), which issue their own licences and have their own plumbing code; the Board also issues natural-gas fitter licences to non-plumbers and a propane gas fitter certificate that applies statewide.
Plumber experience — master ≥ 2 years as a journey + 3,750 hours; journey ≥ 4 years as an apprentice + 7,500 hours Board License Requirements verbatim (read 2026-10-05)	experience	Board requirements: a Master Plumber/Gas Fitter must have held a journey licence for at least two years, completed 3,750 hours of training under a licensed master plumber, and passed a comprehensive written examination. A Journey Plumber/Gas Fitter must have held an apprentice licence for at least four years, completed 7,500 hours of training under a licensed master plumber, completed 32 hours of training in backflow-prevention device testing, and passed a written examination. An apprentice must be at least 16 years old.	S-MD-PL-REQ Source S-MD-PL-REQ — Maryland State Board of Plumbing — Division of Occupational and Professional Licensing Maryland Board of Plumbing — License Requirements — Board License Requirements verbatim (read 2026-10-05) https://www.labor.maryland.gov/license/pl/plreq.shtml Retrieved 2026-10-05 · last verified 2026-10-05 Master Plumber/Gas Fitter: ≥ 2 years as a journey, ≥ 3,750 hours under a master, exam. Journey: ≥ 4 years as an apprentice, ≥ 7,500 hours, 32 hours backflow testing, exam. Apprentice: ≥ 16 years old. Natural-gas fitter and propane-certificate paths verbatim. Plumbing Inspector certification requires a master/journey licence + ≥ 4 years inspector/craftsman experience + exam.
Baltimore County and the WSSC area (Prince George's & Montgomery) issue their own plumbing licences Board overview verbatim (read 2026-10-05)	license	Maryland State Board of Plumbing, verbatim: state plumbing and gas-fit licenses 'are required for work throughout the state except for Baltimore County and the areas served by the Washington Suburban Sanitary Committee - "WSSC" (Prince George's and Montgomery Counties). These two jurisdictions issue their own licenses and have their own plumbing code.' The Board separately issues the statewide propane gas fitter certificate.	S-MD-PL-MAIN Source S-MD-PL-MAIN — Maryland State Board of Plumbing — Division of Occupational and Professional Licensing Maryland Board of Plumbing — overview and the Baltimore County / WSSC carve-out — Board overview verbatim (read 2026-10-05) https://labor.maryland.gov/license/pl/ Retrieved 2026-10-05 · last verified 2026-10-05 State plumbing/gas-fitter licences are required statewide EXCEPT Baltimore County and the WSSC area (Prince George's & Montgomery Counties), which issue their own licences and have their own plumbing code; the Board also issues natural-gas fitter licences to non-plumbers and a propane gas fitter certificate that applies statewide.
All electrical work in Maryland must be performed by a licensed master, journeyperson or apprentice electrician Board notice + BOP §6-605 verbatim (read 2026-10-05)	license	Maryland State Board of Electricians, verbatim: 'All electrical work in Maryland must be performed by a licensed Master, Journeyperson, or Apprentice Electrician. Apprentices must be supervised at all times by a licensed Master or Journeyperson and may not perform work independently. Unlicensed electrical work is illegal. Violations may result in fines of up to $5,000, imprisonment, or both.' §6-605 restates the employment restriction and the job-site presence rule.	S-MD-ELEC-MAIN Source S-MD-ELEC-MAIN — Maryland State Board of Electricians — Division of Occupational and Professional Licensing Maryland State Board of Electricians — overview, insurance requirements, unlicensed-work penalty — Board notice + BOP §6-605 verbatim (read 2026-10-05) https://labor.maryland.gov/license/elec/ Retrieved 2026-10-05 · last verified 2026-10-05 All electrical work must be done by a licensed master, journeyperson or apprentice (apprentices supervised at all times); unlicensed work is illegal and may bring fines up to $5,000, imprisonment, or both. Insurance to hold a licence: GL ≥ $300,000 and property damage ≥ $100,000; insurer must notify the Board 10 days before cancellation.
Licensed electricians, plumbers and HVACR contractors are EXEMPT from the MHIC licence within their scope Business Regulation §8-301(c)(4) verbatim (read 2026-10-05)	exemption	Business Regulation §8-301(c)(4) verbatim: the MHIC licence does not apply to 'an architect, electrician, plumber, heating, ventilation, air-conditioning, or refrigeration contractor, or other person who: (i) is required by State or local law to meet standards of competency or experience before engaging in an occupation or profession; (ii) currently is licensed in that occupation or profession under State or local law; and (iii) is: 1. acting only within the scope of that occupation or profession; or 2. installing a central heating or air-conditioning system.'	S-MD-BR-8-301 Source S-MD-BR-8-301 — Maryland General Assembly — Annotated Code of Maryland (mgaleg.maryland.gov) Business Regulation §8-301 — License required; exclusions (incl. the (c)(4) trade exemption) — Business Regulation §8-301(c)(4) verbatim (read 2026-10-05) https://mgaleg.maryland.gov/mgawebsite/Laws/StatuteText?article=gbr&section=8-301&enactments=false Retrieved 2026-10-05 · last verified 2026-10-05 §8-301(a): a contractor licence is required to act as a contractor in the State; (b): a salesperson or contractor licence to sell a home improvement. §8-301(c)(4) exempts a licensed electrician / plumber / HVACR contractor (or other licensed occupation) acting within scope, or installing a central heating/air-conditioning system.

06 Rule: MD-PLUMBING-LICENSE

Maryland Board of Plumbing licences individuals who provide or assist in providing plumbing and gas services; classes are master/journey/apprentice plumber-gas fitter, limited master/journey plumber, master/journeyman/apprentice natural gas fitter, and a propane gas fitter certificate.

Outcome	Conclusion	Caveats
license-required	plumbing_license_required	—

Rule confidence: confirmed. Missing inputs produce NOT_DETERMINED — never a forced answer. Sources: S-MD-PL-MAIN S-MD-BOP-12-101

07 Rule: MD-ELECTRICAL-LICENSE

All electrical work in Maryland must be performed by a licensed master, journeyperson or apprentice electrician (apprentices supervised at all times). Unlicensed electrical work is illegal; fines up to $5,000, imprisonment, or both.

Outcome	Conclusion	Caveats
license-required	electrical_license_required	A licensed master or journeyperson must be present at the job site (§6-605(b)).

Rule confidence: confirmed. Missing inputs produce NOT_DETERMINED — never a forced answer. Sources: S-MD-ELEC-MAIN S-MD-BOP-6-101

08 Rule: MD-MHIC-TRADE-EXEMPTION

Business Regulation §8-301(c)(4): a licensed electrician, plumber, HVACR contractor or architect acting only within the scope of that occupation/profession, or installing a central heating or air-conditioning system, is NOT required to hold the MHIC contractor licence.

Outcome	Conclusion	Caveats
exemption-applies	mhic_exemption_applies	The exemption is scoped: home improvement OUTSIDE the trade scope still needs the MHIC licence.
exemption-not-available	mhic_license_required	—

Rule confidence: confirmed. Missing inputs produce NOT_DETERMINED — never a forced answer. Sources: S-MD-BR-8-301

09 Rule: MD-PLUMBER-EXPERIENCE

Master Plumber/Gas Fitter: ≥ 2 years as a journey + 3,750 hours + exam. Journey Plumber/Gas Fitter: ≥ 4 years as an apprentice + 7,500 hours + 32 hours backflow testing + exam.

Outcome	Conclusion	Caveats
master	plumber_experience_requirements	—
journey	plumber_experience_requirements	—

Rule confidence: confirmed. Missing inputs produce NOT_DETERMINED — never a forced answer. Sources: S-MD-PL-REQ

10 Which credential for which part

Part of the job	Maryland credential	Source
The remodel / replacement itself	MHIC home improvement contractor licence (rule MD-MHIC-LICENSE)	S-MD-BR-8-301
Plumbing / gas	Maryland Board of Plumbing licence (master plumber covers plumbing AND natural gas) — rule MD-PLUMBING-LICENSE; state licence except Baltimore County / WSSC	S-MD-PL-MAIN
Electrical	licensed electrician, present at the job site (rules MD-ELECTRICAL-LICENSE, MD-ELECTRICAL-JOBSITE)	S-MD-ELEC-MAIN
Trade acting within scope	exempt from the MHIC licence (§8-301(c)(4)) — rule MD-MHIC-TRADE-EXEMPTION	S-MD-BR-8-301

Note: the Baltimore-County/WSSC plumbing carve-out and the §6-605(b) electrical job-site rule (licensed master or journeyperson present at each electrical job site) are stated in full on the Maryland jurisdiction page.

Evidence

S-MD-BOP-6-101statute

Maryland General Assembly — Annotated Code of Maryland (mgaleg.maryland.gov)

Business Occupations and Professions §6-101 — Electrician definitions (master/journeyperson/apprentice; local boards)

https://mgaleg.maryland.gov/mgawebsite/Laws/StatuteText?article=gbo&section=6-101&enactments=false