Guides · State ladders
Maryland's gate is 7,500 hours — and Maryland adds a confusion most states do not have: more than one authority can be “your” licensing authority.
The state route: hold an apprentice license for at least 4 years, document 7,500 hours under a master plumber, complete 32 hours of backflow training, and pass the journeyman exam. The master step beyond it requires 2 more years and 3,750 additional hours.
In the Washington suburbs, WSSC (the Washington Suburban Sanitary Commission) licenses plumbers in its territory; Baltimore County runs its own system. Which authority licenses your work depends on where the work is — an answer no generic guide can give you and the reason Maryland's page on this site names all three.
Run your hours in the eligibility checker; the full map is on the Maryland ladder page.
