Cross-connection control and backflow prevention assemblies protect drinking water by preventing contaminated water from reversing flow and entering the customer's system and possibly the public drinking water system as well.
Learn more essential information about backflow prevention for residential water customers, including how you can help protect your home water system and the WSSC Water supply.
Did you recently receive a courtesy educational notice from WSSC Water regarding annual testing for your backflow prevention assembly (PDF 121 KB)? Let us help you understand what this means and why it's so important for keeping our water supply safe and drinkable!
The first step is understanding what a backflow prevention assembly is and why it's so important to protect cross-connections from backflow.
Learn more about cross-connections and backflow
Your letter identified the testable backflow prevention assembly that WSSC Water's records show you have installed on your property. This could be part of several different residential systems including, but not limited to:
Since their inception, residential fire sprinkler systems have been supplied with water by three different piping arrangements. The following describes the details of each variation:
Testable Double Check Valve Assemblies: The code required homes constructed from 2007 to 2009 to install the testable version of a dual check valve. Because the code was changed to allow non-testable dual check valves in lieu of testable double check valve assemblies, homeowners have two choices for maintenance and upkeep:
A fire sprinkler design engineer initially designs and calculates fire sprinkler system requirements to include a code-compliant backflow preventer.
Changing the backflow preventer from a testable assembly to a non-testable dual check valve alters the original engineered design. Therefore, proof of coordination with a certified fire sprinkler contractor is required and the Office of the Fire Marshal may have additional requirements.
If an existing testable backflow prevention assembly is replaced with a non-testable dual check valve, the homeowner or their contracted registered plumbing firm shall:
Dual Check Valve: This is the most common method of protection. The backflow devices are considered non-testable and the only required maintenance is rebuild or replacement of the device once every five years. A tag should always be hanging from the device identifying installation date, expiration date or both.
Passive Purge: Up to 2007, some homes were allowed to forego a physical backflow device in lieu of a system where stagnant water was purged from the system with usage of one or more toilets in the home. Typically, the water supply to one of the upper floor toilets was piped from the fire sprinkler system; upon each use, fresh water was introduced into the fire sprinkler system.
If a dual check valve is not present, you can perform an easy test to verify if you have a passive purge system. Shut off the water supply to the home by operating the main valve above the meter and past the sprinkler system “take-off.” Then, open the cold supply to a bathtub on the upper floor to ensure the water is off. Now, flush each toilet.
If connected to the normal water distribution piping, the tank will not refill. If connected to the fire sprinkler system, the toilet will refill despite the water being turned off to the rest of the home. This confirms the presence of a passive purge system.
No backflow-related maintenance is required, just be sure to continue using that specific toilet on a periodic basis to ensure fresh water is routed into the sprinkler system.
Homeowner resources for obtaining any required county permits:
Automatic irrigation systems pose a significant threat to the drinking water system. By their nature, sprinkler heads may reside in a pool of yard/animal waste, pesticides and/or fertilizers. And because the supply lines are under constant pressure and flow, and controlled by underground control valves, these systems must be properly protected against backflow.
There are two types of backflow prevention assemblies allowed for in-ground irrigation and lawn sprinkler systems:
PVBs may be winterized in place; RPs must be removed and placed in a warm storage area. Both assembly types require an annual field test and code-compliant reporting of the field test results at the time of spring seasonal start-up.
Installation, repair, replacement and/or annual testing must be performed by a plumbing services firm (licensed plumber). Their plumbers must be at least of the “journeyman” license level and must be licensed cross-connection technicians. Do not be afraid to ask for proof or check their license at the links provided on this page!
Hint for owners with irrigation systems: Make the testing part of your spring start-up contract. The irrigation firms may be able to procure the most favorable pricing due to their ability to deal in volume with plumbing services firms.
The WSSC Plumbing and Fuel Gas Code requires annual testing for all installed testable backflow prevention assemblies. A lawn irrigation system is the most common type of system protected by a testable backflow prevention assembly. Additionally, the WSSC Plumbing and Fuel Gas Code requires that all backflow prevention assemblies be tested annually as well as immediately following installation, repair or relocation.
WSSC Water does not perform backflow prevention assembly testing.
By code, only WSSC-licensed and -registered journeymen or master plumbers who are also certified cross-connection technicians may test and repair backflow prevention assemblies.
Journeyman and master plumbers certified as cross-connection technicians will have completed an initial WSSC Water-approved 32-hour certification course (recertified every 3 years).
Additionally, per the WSSC Plumbing and Fuel Gas Code, only plumbing firms trading under the license of a registered/insured master plumber may provide plumbing services, which include the installation, testing, and replacement of any testable backflow assembly.
In addition to previously mentioned cross-connections protected by testable backflow prevention assemblies, non-testable backflow devices also protect several types of residential cross-connections. According to the WSSC Plumbing and Fuel Gas Code, replacing or rebuilding non-testable backflow prevention devices shall be exempt from a permit requirement and may be performed by the homeowner in residential applications only.
Owners of single-family homes and townhomes can only rebuild or replace non-testable backflow devices, including:
If a residential customer rebuilds or replaces a non-testable device, they must attach an updated non-testable device tag to the device. WSSC Water has options for our residential customers to self-print or request non-testable device tags.
Non-Testable Devices and Hose Bibb Tags (PDF 842 KB)
Piggyback-style townhomes and other forms of multi-unit construction are not included in this category; these type properties contain shared plumbing systems and are commercial in nature, requiring registered plumbing firms to perform the plumbing work.
Modern plumbing fixtures generally have built-in backflow protection. For instance, a faucet spout terminates above the flood rim level of the sink or tub. If the sink or tub is full of dirty water or worse, backed-up sewage, there is no possible way for a backflow because of the air gap created by the elevated spout. Toilet fill valves, clothes washers, dishwashers and refrigerator/ice makers also employ some type of built-in air gap as their method of protection.
Select any of the following specific examples to learn more about their backflow prevention requirements. And if you are still uncertain, find a WSSC-licensed plumber to consult on proper connections and protection requirements or contact WSSC Water by phone or email: 301-206-8886 or [email protected].
Handheld shower heads are required to be protected against backflow in one of two ways:
Vacuum breakers are considered non-testable and may be installed or replaced by a homeowner. Other non-testable devices may require a permit. Consult with a licensed plumber or call 301-206-4004.
Kitchen and lavatory faucets must also meet ASME A112.1.2 or additional backflow prevention is required.
Because of their portability and universal ease of connection, general purpose/garden hoses pose one of the greatest risks for backflow occurrences. In addition, there is a general misunderstanding or underestimation of hazard level pertaining to what hoses are connected to or what they are left submerged in.
In residential applications, the typical way to protect the drinking water system from the hose and its uses is to outfit the hose bibb (spigot/valve) with a vacuum breaker.
Hose bibbs are available with integral vacuum breakers. Vacuum breakers also can be purchased separately and screwed directly onto the outlet threads of the bibb. In this case, the vacuum breaker, in turn, has hose threads to connect the hose to.
Vacuum breakers are very inexpensive but provide a high and low hazard protection against backsiphonage and limited head (typically less than 10 feet) backflow.
Every hose bibb, regardless of age or usage, must be outfitted with a vacuum breaker meeting the product standard/listing ASSE 1011 or ASSE 1019.
ASSE 1011 vacuum breakers are considered non-testable and may be installed or replaced by a homeowner.
Where water is connected to a residential heating system boiler as a make-up water supply, it must be protected by a dual check valve with integral vent (standard number ASSE 1012).
This device is considered non-testable and must be rebuilt or replaced every five years.
If chemicals are added to the heating water system (this is not common), an ASSE 1013 must be installed and special provisions for drainage need to be considered.
Yearly testing by a licensed cross-connection technician working for a registered firm then becomes mandatory.
Not a very common item for any household and with the advent of digital photography, photo developers and dark room sinks are certainly a rarity these days; they do, however, still exist!
When connected to the home’s water distribution system, backflow prevention is a must. If connected to a tank or sink, a non-testable device (standard number ASSE 1012), may be utilized.
If chemical injection is present or an automatic developer is used, a testable assembly (standard number ASSE 1013), must be installed and special provisions for drainage need to be considered.
Yearly testing by a cross-connection technician working for a registered firm then becomes mandatory.