Q.Do we need a permit to add a basement bathroom in Maryland?

A.Yes. A basement bathroom permit is needed in Maryland, and who issues it depends on your address: WSSC Water in Montgomery and Prince George's, and the county or city permit office everywhere else in the region.

A new basement bathroom means new drains, a new vent, new supply lines and, if the room sits below the sewer pipe, a pump. Each office below issues plumbing permits, and a new bathroom is squarely the kind of work they cover. What changes from place to place is the office, the license the plumber must hold, and whether a homeowner can apply at all.

Short version: plan on a licensed plumber pulling the plumbing permit and a licensed electrician doing the wiring. If an ejector basin or upflush unit is part of the plan, that isn't optional anywhere.

Who issues a basement bathroom permit in Montgomery and Prince George's?

WSSC Water. Besides supplying the water, it runs plumbing code enforcement in both counties, and since December 1, 2025 it has enforced its 2024 plumbing and gas code, built on the 2024 International Plumbing Code.

WSSC's homeowner guidance says most plumbing projects in its area must be handled by a plumber it has licensed, and applications are filed online only, through ePermitting. Framing, finishing and electrical permits for the new room are a separate conversation with your county.

Can a homeowner pull the permit?

In WSSC territory, sometimes. Under code section 105.9, an owner who lives in a single-family house or duplex and isn't fixing it up to sell or rent can sign an affidavit and get a permit after passing WSSC's open-book exam at 70 percent or better. The same section rules out projects with seven or more fixtures, below-grade piping deeper than 4 feet, and any gas work, and it requires containment backflow protection.

A three-piece bath may squeak under those limits on paper. Our advice is firmer: if the bathroom needs an ejector or a macerating unit, the job belongs to a licensed plumber holding the permit, with a licensed electrician on the pump circuit. Outside WSSC, Baltimore County lets only a county-licensed plumber apply, and for Howard and Anne Arundel we couldn't confirm a homeowner route, so ask the county.

Which office handles it elsewhere in Maryland?

The details live on each office's own pages: Baltimore County, the Baltimore City building code, Howard County, Anne Arundel and Frederick County. For a wider look at how the offices split up, see who issues plumbing permits.

What license should the plumber have?

The Maryland State Board of Plumbing handles master, journeyman and apprentice licensing statewide, except in Baltimore County and the WSSC area, which license their own. A plumber with a state license may still need the local one. Each registry has its own lookup; our license-checking guide lists them.

Why does the pump make the permit non-negotiable?

Because the inspector is checking things you can't see once the walls close. For a pumped bathroom, that list includes the basin's sealed lid and vent, the paired check and shutoff valves on the discharge line, and a pump able to pass 2-inch solids from a toilet. In WSSC homes, it also means no air admittance valve on the basin unless an engineer designed the vent. Upflush units must carry one of the two macerator certifications the code names.

Under the WSSC code, a room whose fixtures sit lower than the next upstream manhole's rim also needs a backwater valve, with an access cover labeled so nobody tiles over it; see whether to add a backwater valve. The draining options themselves are in bathrooms below the sewer line.

Getting the permit side right

1. Confirm which office covers your address, and in Frederick County, see if the address falls inside Frederick city limits or Mt. Airy.
2. Settle the draining method (gravity, ejector basin or upflush unit) with a licensed plumber.
3. Check the plumber's license with the state board, WSSC or Baltimore County, whichever applies.
4. Have the plumber file the permit before any concrete is cut or walls go up.
5. Book a licensed electrician for circuits, and ask the county whether the wiring needs its own permit.
6. File the permit card and the inspector's final sign-off where you keep the deed.

The bottom line

You need a permit. In Montgomery and Prince George's it comes from WSSC Water; elsewhere, from the county or Baltimore City. If the bathroom needs an ejector or upflush unit, let a licensed plumber pull it, with a licensed electrician for the wiring, and keep the inspection record for the day you sell.

Readers also ask

Does a homeowner permit cover an ejector pump in WSSC?

WSSC's homeowner permit has limits on fixtures, depth and gas, but this column's advice is simple: pumped sewage systems are licensed-plumber work with a permit.

How do we apply for a WSSC plumbing permit?

Online, through WSSC's ePermitting system. Paper applications are no longer taken.

Can we finish the bathroom first and get the permit later?

Not a good plan. Inspectors need to see the drains, vents and basin before walls and floors cover them, and opening finished work costs more than doing it in order.

Does the City of Frederick use the county's permit office?

No. The county office leaves the City of Frederick and the town of Mt. Airy out of its coverage, so ask the city or town directly.

Will a basement bathroom need a backwater valve to pass inspection?

In WSSC areas, yes when the new fixtures are lower than the rim of the closest upstream manhole on the public or private sewer. The valve's access cover has to carry a permanent label.