Commercial / Industrial Customers

Built-in Protection: 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.

Residential-type kitchen and lavatory faucets, constructed within the United States with integral or auxiliary spray heads, generally do not need additional backflow prevention devices.

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 complacency (underestimation of hazard level), with what hoses are connected to or with what they are left submerged in.

For general 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 very good level of protection against backflow.

Every hose bibb, regardless of age or usage, must be outfitted with a vacuum breaker meeting the product standard/listing American Society of Sanitary Engineering (ASSE) 1011 or ASSE 1019.

Vacuum breakers are considered non-testable and may be installed or replaced by an owner, tenant, property manager or maintenance staff.

Just because someone terminated a water supply line with a hose bibb or hose thread connection does not mean a standard vacuum breaker is an adequate level of protection. The applications where a hose-type connection is utilized are too numerous to list, however please use the following guidelines as well as the WSSC Water Plumbing Code Table 5.2 to determine if additional or alternate backflow protection is required:

• Hose is used to connect a water-utilizing piece of equipment (basically a permanent connection): Backflow protection should be commensurate with the level of hazard.
• Hose connection(s) are present in areas where high hazards are present such as vehicle repair shops; sewer pumps; industrial processes, etc.: a reduced pressure-principle-type backflow prevention assembly is required.
• To discuss applications not covered here, please contact the cross-connection program at one of the following numbers:
  • Prince George's County: 301-206-8601  
  • Montgomery County: 301-206-7932

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. In addition, extreme high-pressure air is typically used to winterize (blow out) the underground pipes; this greatly increases the probability of backflow. Because the supply lines are under continuous pressure and controlled by underground control valves, a typical vacuum breaker is not an appropriate form of protection against backflow. 

There are two types of backflow prevention assemblies allowed: 

1. Pressure vacuum breaker (PVB) - ASSE 1020: This assembly must be able to be located outside, one foot above the highest sprinkler head, and no more than five feet above grade at the installed location. 
2. When the parameters for a PVB cannot be met, a reduced pressure principle (RP) - ASSE 1013 shall be installed. Required to be outside, no restriction on elevation of sprinkler heads, and mounted 18-24 inches above grade at the installed location.

PVB may be winterized in place; RPs must be removed and placed in a warm storage area. Both assemblies require their annual test 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 also possess a separate cross-connection technician certification. Do not be afraid to ask for proof!

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.

Since their inception, commercial fire sprinkler systems have been supplied with water by several different piping and metering arrangements. The following describes the details of each variation:

1. Limited system (timeless): In this arrangement, water is supplied to a limited number of sprinkler heads directly from the potable (drinking) water system. If the sprinkler head lateral is less than two feet in developed length (measured from the potable main to a single head) and constructed of material acceptable for potable water, no backflow protection is required. Up to seven heads can be supplied from a branch system(s) where the largest pipe diameter used is 1-1/2 inches. Each connection to the potable system shall be protected with an ASSE 1024 double check valve (DCV) backflow device. Code requires rebuilding or replacement of the device every five years. A tag shall always be hanging from the device identifying installation date, expiration date, or both.
2. Up to April 30, 2007, and regardless of metering arrangement, fire sprinkler systems were outfitted in one of the following three piping arrangements:
   1. Double Check Valve Assembly (DCVA) - ASSE 1015: A testable backflow prevention assembly requiring annual testing and reporting.
   2. Single Check Valve: A non-testable backflow prevention device that requires rebuilding or replacement every 5 years. A tag should always be hanging from the device identifying installation date, expiration date or both. If no tag is present, the single check valve will be perceived to be past the required 5-year maintenance requirement and warrant replacement.
   3. Unprotected system: A testable backflow prevention assembly was required based on the following:
      1. ASSE 1015 DCVA fire water is previously metered or a current supervised sprinkler agreement is on record.
      2. ASSE 1048 DCDA unmetered or unsupervised fire water.
      3. Hydraulic Consideration for the impact of adding a backflow assembly is the owner responsibility and shall be presented to the appropriate county or city fire official for approval.
3. May 1, 2007, to February 28, 2019: Fire sprinkler systems were outfitted using one of the following methods:
   1. An ASSE 1015 DCVA required where fire water is previously metered, typically by a large outside meter.
   2. An ASSE 1048 DCDA required where fire water is not previously metered, typically when domestic water is/was metered by an inside meter. The 1048 contains two testable 1015 BFPs; one main assembly and the other situated on the bypass feature. In addition, the bypass contains a pre-piped meter accommodation. The 1048 was to be purchased without a meter; WSSC Water supplied and set the meter in this arrangement as a “tattle tale” device to ensure the fire water is not used for any other purpose other than fire-fighting. Within this timeframe, the ASSE 1048 Type 2 bypass was introduced by several manufacturers. The Type 2 bypass has a single check in the bypass around the second check module and utilizes the first check module as preservation of doublecheck valve protection for the bypass incorporated into the design of the ASSE 1048 Type 2 assembly.
4. March 1, 2019, to present: fire sprinkler systems shall be outfitted using one of the following methods:
   1. An ASSE 1015 DCVA.
   2. Owner/engineer option to specify the design preference to install an ASSE 1048 DCDA. If an ASSE 1048 Type 1 or Type 2 assembly is permitted and installed as the owner/engineer design preference, the owner will be responsible for performing two annual field tests for the life of the ASSE 1048 assembly, maintaining both the primary assembly and the bypass check modules, maintaining all assembly and device components, and metering and/or detection of flow shall be the ongoing responsibility of the building/facility staff.
5. Non-Standard Fire Protection Systems: Where chemicals are introduced, normally as an anti-freeze agent or where the system itself utilizes chemicals to mix with the fire water to create an enhanced fire-fighting material, an ASSE 1047 Type 1 or Type 2 Reduced Pressure Principal Backflow Prevention Assembly shall be installed as follows:
   1. Up to February 28, 2019, WSSC requirements were:
      1. An ASSE 1013 RP was required in applications where a 1015 is specified in 3.1
      2. An ASSE 1047 RPDA was required in applications where a 1048 is specified in 3.2.
   2. From March 1, 2019, to present:
      1. An ASSE 1013 Reduced Pressure Principle Backflow Prevention Assembly (RPDA) shall be installed.
      2. Owner engineer option to specify the design preference to install an ASSE 1047 RPDA. If an ASSE 1047 RPDA is specified for installation by the design engineer, owner will be responsible for performing two annual field tests for the life of the assembly, maintaining all assembly and/or device components, and metering and/or detection of flow shall be an ongoing responsibility of the building/facility staff.

Whether for domestic use, fire protection, or an industrial application, the required backflow prevention assembly or device shall be upstream (ahead of) the booster pumping system.

Where water is connected to a heating or cooling system as a make-up water supply, it must be protected by a RP type Testable Backflow Prevention Assembly - ASSE 1013. This assembly is considered “testable” and must be tested yearly. An air gap at the cooling tower is a sub-standard form of protection due to potential bacteria growth within the spout caused by exposure to contaminated vapors and the extended time in a “no flow” condition.

Not a very common item anymore with the advent of digital photograph; photo developers and sinks are certainly a rarity these days. But when connected to the 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 and yearly testing by a plumber is mandatory.

Medical/dental vacuum systems, sterilizers and other medical equipment utilizing potable water shall be isolated with a RP type backflow prevention assembly – ASSE 1013.

In-line cartridge filters shall be isolated with a dual check valve (DCV) – ASSE 1024. Treatment systems incorporating chemical injection, reverse osmosis, de-ionization, etc. shall be isolated with a RP type backflow assembly – ASSE 1013. Ultra-violet light (UV) treatment systems do not require backflow prevention.

Carbonated beverage dispenser shall be isolated with an ASSE 1022 backflow device. All other beverage dispensers may use either an ASSE 1022 or 1024 device. Where 1022s are installed, the area shall be capable of handling the discharge.

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.

Pipe applied or spout applied vacuum breakers cannot be subjected to continuous pressure. They must be installed downstream of a water control point and the downstream process must relieve pressure in each off cycle. Pipe applied atmospheric vacuum breakers (ASSE 1001) shall be a minimum of 6 inches above the highest downstream use and installation of the ASSE 1001 has additional requirements which must be observed. Spill-resistant (ASSE 1056) and pressure vacuum breakers (ASSE 1020) shall be a minimum of 12 inches above the highest downstream use.

Refer to WSSC Water Plumbing and Fuel Gas Code, Chapter 5 and Table 5.2 or consult with a licensed plumber regarding proper connection and protection requirements or contact a WSSC Water inspector by phone or email: 
301-206-8886 or plumbingplansreview@wsscwater.com.