Cross-Connections and Backflow Prevention: Ensuring Safe Drinking Water

Key details on how we protect your water supply through Cross-Connection Control.

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.
Cross-Connection Frequently Asked Questions (FAQs)
Fire Hydrants: Maintenance & Meter Leases
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.
Backflow & Hosebib Tags
For Non-Testable Devices (Rebuild/Replace Every 5 Years)

What is Cross-Connection?

A cross-connection is a physical link between the potable water system and equipment or fixtures that could contaminate the water.

What is Backflow Prevention?

Backflow occurs when contaminants flow back into the water system, often caused by pressure changes.

What Can Cause a Backflow?

Hydraulic events, such as:

Plumbing repairs
Broken water mains
Power outages
Firefighting efforts

Built-in Protection and Additional Protection

Most modern plumbing fixtures (like sinks, toilets, dishwashers) have built-in backflow protection, such as air gaps. However, certain systems, such as handheld shower heads and lawn irrigation systems, require additional protection, such as backflow preventers. Additional protection is also important in commercial and industrial setups where direct connections are needed for water flow.

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 WSSC Water’s 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 Registered Licensed WSSC Water Plumber.

Backflow Prevention Devices and Testing

Testable Backflow Preventers

Backflow Prevention Assemblies are generally required for hazardous cross-connection applications.
Must be tested annually, as components wear out over time or become blocked. Required by federal, state and local requirements.
If tests fail, assemblies need cleaning, rebuilding and retesting or replacement if irreparable.

Non-Testable Backflow Preventers

Backflow Prevention Devices are typically used for less hazardous connections.
May need rebuilding or replacing every five years or when they visibly fail.

Application of Backflow Preventers

Refer to Chapter 5 of the WSSC Water Plumbing and Fuel Gas Code for a complete list.

Testable Applications:

	Irrigation (Homes & Businesses)
	Medical Equipment, Laboratories
	Car Wash

Non-Testable Applications

	Handheld Shower Heads
	Commercial Ice Makers
	Emergency Eye Wash

Non-Testable Devices (Rebuild/Replace Every 5 Years)

ASSE 1012, 1022, 1024, and 1081 - Dual Check Valves with and without Atmospheric Vent (including for Carbonated Beverage Dispensers); and Backflow Preventer with Atmospheric Vent and Pressure Reducing Valve

These devices require tagging to identify the installation and expiration date. Homeowners can replace them without a permit or inspection.

For a more comprehensive list, see the WSSC Water Plumbing and Fuel Gas Code.

How to Submit Backflow Test Reports

Registered Licensed WSSC Water Plumbers can purchase numbered forms. After completing a test, registered cross-connection technicians must submit their reports electronically to WSSC Water within 30 business days.

Self-Surveys and Compliance

reminder

WSSC Water needs your help to catch-up on years of non-reporting and non-compliance. Commercial and industrial water customers are asked to complete a self-survey of all connections on their property. Complete your self-survey today.

The self-survey can be completed by the owner, tenant or a plumber. For accurate results, ensure that both owners and tenants share this notice. Homeowners with testable backflow assemblies should also self-report via phone or email.

Email: InspectionSupport@wsscwater.com
Phone: 301-206-4004

Seasonal Water Use Systems

Test backflow assemblies each spring when systems are reactivated (e.g., irrigation, pools, pool houses, summer homes). All annual test results are due by May 1st.

Tip for owners: Consider including backflow testing to your spring start-up contract for pools and irrigation systems. Companies often offer better pricing due to their volume.

New Construction

WSSC Water Code officials, engineers, plumbing installers and property owners ensure proper backflow protection in new homes.

However, ongoing maintenance is necessary to keep systems functioning properly.

The Cross-Connection Control Program

Our inspectors are actively identifying unprotected or improperly protected cross-connections. With eight dedicated inspectors covering the service area, we identify unprotected or improperly protected cross-connections based on priority.

team

Backed by a strong administrative team, we maintain our database, send reminders, and run our self-survey program to keep everything running smoothly.

The database records information about backflow preventers tested annually, helping to keep track of safety measures. Additionally, it identifies outdated assemblies and generates reminder notices for re-testing.

Definitions:

Air Gap: The un-obstructed vertical distance between a water outlet and the flood rim level of a potential source of contamination; the air gap shall not be less than twice the diameter of the water outlet and never less than one (1) inch.
Backflow: The undesired reverse flow of contaminants into the potable water from an “end-use” hazard and is typically driven by common, but unfavorable, hydraulic events in either the public or private water distribution system.
Direct Connection: Water piping connected directly (without an air gap) to an “end-use” where a potential source of contamination exists.
Long Form Permits: The “first time” installation of a testable backflow assembly or relocation of an existing testable assembly requires a long form permit and inspection.
Short Form Permits: The replacement of an existing backflow assembly requires a short form permit and inspection.
Plumbing Services: To install, maintain, extend, alter, or remove piping, a plumbing fixture, a plumbing appliance, a plumbing appurtenance, or other plumbing apparatus within a building or on-property where such plumbing is connected to a public or private sewerage system or connected to a private or public water system.

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