What Every Homeowner in the WSSC
Area Needs to Know About
Plumbing Requirements
Permits. Backflow testing notices. Water heater rules. Licensed plumber requirements. This is the plain-English guide — no jargon, no upsell — just what actually applies to your home and what happens if you skip it.
The WSSC Jurisdiction Is Different From the Rest of Maryland
Most of Prince George’s County and Montgomery County falls under the Washington Suburban Sanitary Commission (WSSC) — a water and sewer authority that also functions as its own independent plumbing code and licensing jurisdiction. This means the rules in your neighborhood are not the same as the rest of Maryland.
WSSC sets its own plumbing code (currently the 2024 WSSC Plumbing & Fuel Gas Code, effective December 1, 2025), issues its own plumber licenses, and enforces its own permit and inspection requirements. A licensed Maryland plumber without a WSSC license cannot legally work on your home here.
If a plumber pulls the wrong permit — or no permit — work that gets done on your home can be flagged during a future sale inspection, require forced removal, or void homeowner’s insurance claims. Always verify WSSC licensing before work begins.
This guide covers the five areas of WSSC plumbing rules that homeowners encounter most frequently: permit requirements, backflow testing, water heater regulations, what to do when you receive an official notice, and how to verify a plumber’s credentials before hiring.
Permits: What Requires One and What Doesn’t
WSSC requires permits for most plumbing and gas work. The permit process exists so that an inspector can verify work was done correctly before it’s covered up or put into service. Only firms operating under a licensed WSSC master plumber may pull permits on your behalf — this is why you can’t hire a handyman or out-of-jurisdiction plumber for most plumbing jobs here.
Always Requires a WSSC Permit
- Water heater replacement or new installation
- Underground water line repair (house to meter)
- New bathroom or kitchen plumbing rough-in
- Gas appliance installation (furnace, dryer, range)
- New gas line or gas line extension
- Sewer line repair or replacement
- Irrigation system with backflow preventer
- Boiler installation or replacement
- Main water service replacement
- New fixture rough-in (toilet, sink, shower)
Typically Does Not Require a Permit
- Replacing a faucet with the same style faucet
- Unclogging drains (routine drain cleaning)
- Toilet flapper, fill valve, or handle replacement
- Repairing a small supply line under a sink
- Replacing a showerhead
- Water softener maintenance
- Fixing a running toilet (internal components)
- Minor exposed pipe insulation
Permit Services at WSSC is open Monday through Friday, 7am–4pm (Wednesday closes at noon), at 14501 Sweitzer Ln, Laurel, MD 20707. Your plumber should handle permit submission on your behalf before starting work.
The Permit Process, Step by Step
Your plumber submits the permit application
Only a licensed WSSC master plumber (or a firm operating under one) can pull permits. They submit the application with their WSSC license number and proof of liability insurance naming WSSC Water as Certificate Holder.
Work begins after permit approval
Work cannot legally begin before the permit is approved. If a contractor asks to “start now and file the permit later,” that’s a red flag. Unpermitted work puts you — the homeowner — at legal and financial risk.
WSSC coordinates inspection milestones
For larger jobs, a WSSC inspector may need to visit at specific stages — for example, before drywall covers new pipe runs. Your plumber coordinates this scheduling.
Final approval closes the permit
Once work passes final inspection, the permit is closed. Keep a copy of all permit paperwork — you may need it when you sell your home. Real estate transactions often surface unpermitted work, which can derail a closing.
Backflow Testing: What It Is, Who Needs It, and What to Do If You Get a Notice
Understanding Backflow in Plain English
No plumbing jargon — just what you actually need to know as a homeowner
What Is Backflow?
Your plumbing is designed to flow one way: clean water in, wastewater out. Backflow is when that direction reverses — usually due to a sudden pressure drop — potentially pulling contaminated water back into the clean supply. It’s rare, but when it happens, it can affect the entire neighborhood’s water supply, not just your home.
Why WSSC Takes It Seriously
WSSC provides clean water to over 1.8 million people. A single unprotected cross-connection — like an irrigation system without a backflow preventer — can introduce pesticides, fertilizers, or bacteria into the public water supply. This is why the testing requirement exists and why non-compliance can result in water service suspension.
- A backflow preventer is a mechanical device installed at the connection between your property’s water system and the public supply. It has a one-way valve that physically prevents contaminated water from flowing backward.
- WSSC requires these devices to be tested annually because the mechanical components wear out over time. A preventer that was working last year may fail today without any visible symptoms.
- The test itself involves a certified technician connecting calibrated gauges to the device and measuring whether it’s holding pressure correctly. It typically takes 30–60 minutes and does not require excavation or major disruption.
Does Your Property Require Annual Backflow Testing?
Not every residential property requires backflow testing — but more do than homeowners realize. Use this table to understand where your property likely falls.
| Property / System Type | Testing Required? | Frequency |
|---|---|---|
| In-ground irrigation / sprinkler system | Yes — Annual | Every year, regardless of use |
| Residential boiler / hydronic heating system | Yes — Annual | Annual testing required by WSSC |
| Commercial / retail / office building | Yes — Annual | All commercial connections require testing |
| Restaurant / food service facility | Yes — Annual | High-hazard classification |
| Fire suppression / sprinkler system | Yes — Annual | Annual + after any system modification |
| Medical or dental office | Yes — Annual | High-hazard; often requires containment device |
| Multi-family building (apartment / condo) | Yes — Annual | Building-level compliance; owner’s responsibility |
| Standard single-family home (no irrigation, no boiler) | Usually Not Required | Consult with a WSSC-licensed plumber if unsure |
| Any system after repair, relocation, or device replacement | Yes — After Event | Testing required before return to service |
| New backflow device installation | Yes — Initial | Must be tested before first use |
What to Do When You Get a WSSC Backflow Testing Notice
WSSC mails backflow testing notices directly to property owners with registered backflow assemblies. If you received one, here’s exactly what it means and what to do — without panic.
Read the notice carefully for the compliance deadline
Every WSSC backflow notice includes a required completion date. This is not flexible — missing it can trigger enforcement action including fines and, in serious cases, water service interruption. Note the date first.
Confirm the notice is about your property’s device
The notice will describe the type of device and location on your property (e.g., “irrigation backflow preventer at meter pit”). Verify you know where this device is — your WSSC-certified plumber can help locate it if you can’t find it.
Schedule only with a WSSC-certified backflow technician
WSSC backflow testing is restricted to licensed technicians who hold specific cross-connection certification. Not all plumbers qualify. Ask for their WSSC license number and backflow certification before scheduling.
Get the test done and documentation submitted before the deadline
After testing, the technician completes WSSC-required test forms. Passing tests are submitted to close out the compliance requirement. If the device fails, repair or replacement is required before retest — build in time for this possibility.
Keep your copy of the test report
You should receive a copy of the completed test form with pass/fail results and the technician’s certification number. Keep this with your home records — WSSC may request it, and it’s useful at the time of sale.
If you believe the notice was sent in error (e.g., you don’t have an irrigation system), contact WSSC directly at 301-206-4003 to verify. Do not assume it doesn’t apply to you and discard it. Enforcement actions follow missed deadlines automatically.
Water Heater Replacements: The Rules Homeowners Usually Don’t Know
Water heater replacement is one of the most common plumbing jobs in the WSSC area — and one of the most frequently done without a required permit. Here’s what the rules actually require.
What a Compliant Water Heater Installation Looks Like
- ✓Permit is pulled before installation begins. All water heater replacements in the WSSC area require a permit, including like-for-like tank swaps. This is non-negotiable under the 2024 WSSC Plumbing Code.
- ✓Permit is pulled by a WSSC-licensed master plumber — not a handyman, not a big-box store installer who is not WSSC-licensed. Verify the plumber’s credentials before scheduling.
- ✓Gas water heaters require gas permit and WSSC IFGC 2024 compliance. Gas line work including the connector, shutoff valve, and venting must meet the 2024 International Fuel Gas Code as adopted by WSSC.
- ✓Expansion tank may be required. If your home has a closed plumbing system (common with backflow preventers), an expansion tank is required by code to manage thermal expansion from the water heater. A compliant installer will check this automatically.
- ✓Earthquake strapping required for water heaters in certain configurations. The 2024 WSSC code specifies strapping requirements for tank-style water heaters.
- ✓WSSC inspection is scheduled and passed before the permit is closed. You (or your plumber) should receive confirmation of passing inspection.
Failed Home Sale
Unpermitted water heater installs are commonly flagged by home inspectors. This can delay or kill a real estate closing — and the cost of remediation falls on the seller.
Insurance Denial
If an unpermitted water heater fails and causes water damage, your homeowner’s insurance company may deny the claim on the grounds that the installation was not code-compliant.
Safety Risk
Code requirements for water heaters — expansion tanks, T&P valves, proper venting — exist because improperly installed water heaters can fail catastrophically. The permit process catches these issues.
Fines & Forced Removal
WSSC can require unpermitted work to be exposed and redone under permit at the homeowner’s expense. Fines may also apply depending on the nature of the violation.
How to Verify a Plumber Is Actually WSSC-Licensed
This is the most important thing you can do before any plumber starts work on your home. Here’s the simple way to do it — and what to look for.
Ask for the plumber’s WSSC license number directly
Any legitimate WSSC-licensed plumber or firm will provide this without hesitation. Write it down.
Verify using WSSC’s online license lookup
WSSC maintains a searchable directory of licensed plumbing firms at wsscwater.com. You can also call Permit Services at 301-206-4003 Mon–Fri 7am–4pm to verify by phone.
For backflow testing specifically, confirm cross-connection certification
Backflow testing requires additional WSSC certification beyond the standard master plumber license. Ask for the technician’s Pipeline Institute or equivalent backflow certification number.
Confirm they will pull the permit — before work starts
Ask directly: “Will you pull the WSSC permit for this job, and will you send me the permit number?” If the answer is vague or they suggest starting without a permit, find someone else.
Here are the credentials Durance Plumbing carries for WSSC-area work:
Frequently Asked Questions
Need Help With WSSC Compliance?
We Handle It For You.
Whether you got a backflow notice, need a water heater replaced, or just want a straight answer about what’s required for your home — Durance Plumbing has been navigating WSSC requirements for over 20 years. WSSC licensed, backflow certified, and fully insured.