Backflow Laws: Maryland
Maryland Backflow Prevention Laws, Regulations, and Compliance Requirements
Maryland's backflow prevention landscape is shaped by the Maryland State Board of Plumbing, which oversees cross-connection certification programs under Maryland Code of Regulations (COMAR) 09.20.04.02, and by WSSC Water — the Washington Suburban Sanitary Commission — which serves 1.8 million residents in Prince George's and Montgomery counties and serves as both water purveyor and plumbing inspection jurisdictional authority under Maryland law. WSSC's requirements are among the most detailed of any U.S. utility. This guide covers Maryland's state framework, WSSC's program, Baltimore City and County, and other major Maryland utilities.
Maryland State Regulatory Framework
Maryland’s backflow prevention certification requirements are established in the Maryland Code of Regulations (COMAR) at Section 09.20.04.02 — Approved Cross Connection/Backflow Prevention Certification Program — administered by the Maryland State Board of Plumbing under the Business Occupations and Professions Article, §12-306(c). Maryland holds EPA primacy under the federal Safe Drinking Water Act through the Maryland Department of the Environment (MDE).
Under COMAR 09.20.04.02, a cross-connection/backflow prevention certification program must be a 32-hour course approved by the Maryland State Board of Plumbing. Course instructors must hold certification from ASSE, ABPA, USC-FCCCHR, or AWWA. Recertification is required every 5 years (8-hour recertification course). An important limitation: completion of an approved certification program does NOT authorize an individual to install, test, or certify a backflow prevention device unless they are also licensed by the Maryland State Board of Plumbing as a master or journeyman plumber. Apprentice plumbers may assist but not independently certify.
This dual requirement — Maryland State Board of Plumbing license PLUS approved 32-hour backflow certification — means Maryland requires both a plumbing license and a specific backflow credential to perform testing legally, similar to Illinois’s dual requirement structure.
Maryland Plumbing License Requirements
Maryland law requires that only plumbing firms trading under the license of a registered, insured master plumber may provide plumbing services — including installation, testing, and replacement of testable backflow assemblies. Cross-connection technicians must be working under the direction of a WSSC Water-registered and licensed principal master plumber in the WSSC service area. Other parts of Maryland follow the Maryland State Board of Plumbing’s licensing requirements, which establish the same master/journeyman plumber prerequisite.
WSSC as Both Utility and Plumbing Inspector — Unique in the Nation
WSSC Water has a regulatory role that is virtually unique among U.S. water utilities: under the Maryland Public Utilities Article, WSSC is not only the water purveyor for Prince George’s and Montgomery counties but also the plumbing inspection jurisdictional authority for those counties. This means WSSC writes and enforces plumbing code requirements — including the WSSC Plumbing and Fuel Gas Code — in addition to operating its water distribution system. Property owners in WSSC territory are regulated by WSSC in both its water utility capacity and its plumbing inspection authority capacity simultaneously.
Major Water Purveyors in Maryland
WSSC Water (Washington Suburban Sanitary Commission)
WSSC Water serves approximately 1.8 million customers in Prince George’s and Montgomery counties — the largest water utility in Maryland and one of the largest in the Mid-Atlantic region. WSSC’s cross-connection control program is defined in the WSSC Plumbing and Fuel Gas Code Chapter 5 and in WSSC Code of Regulations Section 14.10.110. WSSC has a Backflow Technician license requirement that goes beyond the state baseline.
WSSC Backflow Technician requirements: applicants must be WSSC-licensed Master Plumber, Master Plumber/Gasfitter, Journeyman Plumber, or Journeyman Plumber/Gasfitter; must complete a state-approved 32-hour cross-connection/backflow prevention training program; and must maintain current WSSC Backflow Technician registration. License is valid for 3 years; renewal requires an 8-hour state-approved recertification program. As a prerequisite for taking any WSSC plumbing exam, applicants must have passed a 32-hour state-approved backflow prevention certification program within three years prior to application.
Annual testing is required for all testable backflow assemblies under the WSSC Plumbing Code. Test reports must be submitted electronically through the WSSC Water Cross-Connection Test Report (CCTR) system within 30 business days of the test. WSSC’s automated backflow tracking system permits no grace period — certification and WSSC registration must be current to submit reports.
Non-testable backflow devices (ASSE 1012, 1022, 1024, 1081) must be rebuilt or replaced every 5 years or when they visibly fail, with tags identifying installation date and required rebuild/replacement date. Testable assemblies must be tested annually and rebuilt/replaced when they cannot pass testing. The WSSC Plumbing Code permits homeowners to replace non-testable backflow prevention devices in residential applications without a permit or licensed contractor.
WSSC publishes a list of certified Cross-Connection Service Firms and a separate list of WSSC-licensed firms. WSSC has validated their licensing credentials but does not endorse any firm — property owners may choose any licensed firm from the published list.
Baltimore City Bureau of Water and Wastewater
Baltimore City’s Bureau of Water and Wastewater serves Baltimore City proper and provides wholesale water to Baltimore County and other surrounding jurisdictions. Baltimore City operates under MDE oversight and requires annual backflow testing for all commercial and industrial connections within the city. Testing must be performed by Maryland State Board of Plumbing-licensed plumbers with 32-hour backflow certification.
Baltimore County Department of Public Works
Baltimore County’s Department of Public Works serves the county surrounding Baltimore City. Baltimore County’s cross-connection control requirements align with MDE standards. Annual testing is required for covered assemblies. Test reports are submitted to Baltimore County.
Md. American Water (Anne Arundel, Carroll, and Other Counties)
Maryland American Water serves Anne Arundel County, Carroll County, and other Maryland communities. Maryland American Water’s cross-connection control program aligns with MDE requirements and Maryland State Board of Plumbing credential requirements. Annual testing by Maryland-licensed, certified cross-connection technicians is required.
Harford County, Howard County, and Frederick Water Systems
Harford County Department of Public Works, Howard County Division of Water and Sewer, and Frederick City Department of Public Works each operate cross-connection control programs aligned with MDE requirements. Annual testing is standard. Each jurisdiction’s specific filing requirements and approved tester criteria should be confirmed directly.
WSSC Liability Warning for Property Owners
WSSC Water explicitly warns in its published materials: if you are responsible for a cross-connection — whether unprotected, improperly protected, or out-of-date for service — and a backflow event occurs, you may be held liable for any resulting illness, death, property damage, and WSSC Water system contamination. Testing compliance may help reduce liability. This is not a theoretical risk — WSSC takes the position that documented testing compliance is a material factor in any civil liability assessment related to a backflow contamination event.
Property Owner Compliance Summary for Maryland
Credential: Testing must be performed by a Maryland State Board of Plumbing-licensed journeyman or master plumber who has completed an approved 32-hour backflow certification course. In WSSC territory: WSSC-specific Backflow Technician registration also required.
Annual testing: All testable assemblies must be tested annually. Non-testable devices must be rebuilt or replaced every 5 years (WSSC).
Filing (WSSC): Electronic submission through the WSSC CCTR system within 30 business days. No grace period for expired certifications in the WSSC system.
Other Maryland utilities: Submit results per each utility’s specific procedure within their specified window.
Records: Retain all test reports. WSSC publishes guidance on assembly tags and record documentation requirements.
Find a Certified Backflow Tester in Maryland
Find Maryland-licensed, 32-hour-certified cross-connection technicians registered with WSSC (for Prince George’s and Montgomery counties) and other Maryland utilities at getyourbackflowtested.com/backflow-testing-near-me/maryland-backflow-testing — covering WSSC territory, Baltimore City, Baltimore County, Anne Arundel, and all major Maryland markets.
Maryland Regulatory Reference Links
| Resource / Agency | URL / Link Target |
|---|---|
COMAR 09.20.04.02 — Approved Cross Connection/Backflow Certification Program | |
Maryland State Board of Plumbing | |
WSSC Water — Cross-Connection Control and Backflow Prevention | |
WSSC — Commercial/Industrial Cross-Connection Requirements | |
WSSC — Plumbers, Cross-Connection Technicians & Trainers | |
WSSC Code of Regulations Section 14.10.110 — Backflow Technician Certification | |
Maryland Department of the Environment — Drinking Water |