Commercial / Industrial Customers

Quick Links:

• WSSC Water Plumbing and Fuel Gas Code
  Professionals should refer to the Code when making design, installation and maintenance decisions. This comprehensive document covers applications, testing, backflow prevention and more.
• List of Cross-Connection Approved Firms
  WSSC Water has validated their licensing credentials but does not endorse these firms. You may choose any licensed firm.
• Find a Licensed Plumber
• Explaining Cross-Connection & Backflow
• Backflow & Hosebib Tags
  For Non-Testable Devices (Rebuild/Replace Every 5 Years)

Liability 

Compliance can help reduce your liability. If you are responsible for a cross-connection and a backflow event occurs, you may be held liable for any resulting illness, death or property damage.

The Maryland State Plumbing Code and our Plumbing Code regulate Cross-Connection requirements. Only registered licensed WSSC Water plumbers who are also certified backflow technicians are allowed to install, test or replace backflow prevention assemblies. 

Backflow technicians must be registered as, at minimum, Journeyman Plumbers and have completed a WSSC Water approved 32-hour certification course for Cross-Connection technicians (recertified every 3 years). 

Under Maryland Law, only firms registered under a licensed Master Plumber can perform plumbing services, including backflow prevention assembly installation, repair and testing. Therefore, Cross-Connection technicians must be working under the direction of a plumber.

Why Cross-Connection and Backflow Prevention Matters and What to Do About It

Backflow can contaminate the water supply. WSSC Water requires Cross-Connection devices to prevent this—it's enforceable and could affect your liability. Understanding and respecting the risk of water contamination is a great start. When in doubt, seek help.

Basic guideline: every potable water outlet needs some form of protection; get to know what is needed.

• Have “non-testable” backflow devices rebuilt or replaced as required. 
• Have “testable” backflow assemblies tested yearly and each rebuilt or replaced as needed.

Who’s Responsible? Property Owners vs. Tenants

Property owners are ultimately responsible for all water “end uses” on their property. However, at the first level of follow-up:

• Tenants are responsible for backflow prevention devices or unprotected outlets that they initiated / installed.
  • We may notify the property owner directly if issues aren't resolved.
• Property owners are responsible for devices that are part of the building or campus’ shared or core plumbing and mechanical systems.

Continued non-compliance may result in water or sewer service being shut off.

Common Situations & What's Required

Scenario	Device Needed	Notes
Hose	Vacuum Breaker (ASSE 1011/1019) for garden hose. RP Backflow Assembly (car shops, sewer pumps)	Garden Hose: Required on every hose bibb.  Non-testable.  May be installed by property managers, owners, tenants.  Maintenance tips for cold weather. Hoses in High Hazard Environments: Refer to the Code.
Irrigation	PVB ASSE 1020 or RP ASSE 1013	PVB must be located outside, 1 ft above highest sprinkler head, no more than 5 ft above grade. RP required if PVB parameters can't be met.
Beverage Dispensers	ASSE 1022 backflow device (carbonated). All others:  ASSE 1022 or 1024.	1022 requires an area capable of handling discharge.
Cooling Towers/Boilers	RP (ASSE 1013)	Annual testing required. Air gap alone not sufficient.
Dental/Medical Equipment	RP (ASSE 1013)	Required for vacuum systems, sterilizers, etc.
Fire Sprinkler System	Depends on system type and install date: Limited System: ASSE 1024 Pre-2007: ASSE 1015 (DCVA) or Single Check 2007-2019: ASSE 1015 (DCVA) or ASSE 1048 (DCDA) 2019-Present: ASSE 1015 (DCVA) or optional ASSE 1048 (DCVA) With Chemicals: ASSE 1013 or 1047 (RPDA)	Tags must show install/expiration dates, where applicable. Special testing and maintenance required for DCDA/RPDA options.
Dark Room Sinks/ Film Developers	ASSE 1012 (basic) or ASSE 1013 (if chemicals)	ASSE 1013 requires annual testing and appropriate drainage.

For additional applications:

• Refer to the Code, Table 5.2
• Consult with a plumber regarding proper connection and protection requirements
• Contact a WSSC Water inspector
  • (301) 206-8886 
  • plumbingplansreview@wsscwater.com

Do I Need Containment or Isolation?

Both may be required.

• Containment: At the building's main water entry, to prevent backflow on an entire campus or building
• Isolation: At specific fixtures or equipment
• Since 2007, both are required at most facilities

For existing facilities:

• Older buildings or campuses without containment may need to be retrofitted, requiring a containment backflow assembly, if classified as moderate or high hazard, on a priority basis.

Existing Systems (Grandfather Clause)

Even if a plumbing system was installed under an older code or previously approved by an inspector, it must meet current safety standards. No system is fully "grandfathered in." If there's a health risk, it must be corrected.

See WSSC Water Plumbing and Fuel Gas Code, Sections 502.3.2 & 502.3.3.

Submeters

In general, WSSC Water requires submeters to be installed upstream (ahead of), backflow prevention assemblies.

Booster Pumps

Backflow prevention assembly or devices must be installed ahead of (upstream of) any booster pumping system—whether for domestic, fire, or industrial use.

Non-Testable Devices

ASSE 1012, 1022, 1024 & 1081 backflow devices shall be re-built or replaced every five years. A tag shall always be hanging from these devices identifying installation date, expiration date, or both. Other non-testable devices are good for the life of the fixture or appliance served or until leakage/failure.

Vacuum Breakers

Vacuum breakers, whether applied to a pipe or spout, can't be under constant pressure. Install them after (downstream from) a water control point, releasing the pressure when not in use.

• Pipe-Applied Atmospheric Vacuum Breakers (ASSE 1001): At least 6" above the highest downstream use
• Spill Resistant (ASSE 1056) & Pressure Vacuum Breakers: (ASSE 1020): At least 12" above the highest downstream point

Installation and Drainage Considerations

Backflow assemblies and devices must be easy to access. If they discharge water, install them in areas with proper drainage. Plan for possible large leaks—potentially catastrophic failure and a large volume of sustained discharge. If adequate drainage isn't possible, consider using an automatic shut-off system.

Need to Contact Us?

• Montgomery County: (301) 206-7932
• Prince George's County: (301) 206-8601
• General Cross-Connection Program Support: (301) 206-4004