Residential Customers

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.

Handheld shower heads are required to be protected against backflow in one of two ways:

[Image]

1. Handheld shower spray heads must comply with American Society of Mechanical Engineers (ASME) A112.1.2 or be equipped with an American Society of Sanitary Engineering (ASSE) 1014, which is a backflow device for handheld showers.
2. Where a vessel fills below the flood rim level, as typically done with a deck-mounted tub/shower combination valve, a dual check valve shall be installed on the delivery side of the main tub control valve, or two dual check valves shall be installed in the hot and cold supply lines ahead of the main tub control valve. The dual check valve(s) shall meet the product standard/listing ASSE 1024.

[Image]

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. 

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.

[Image]

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:

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 backflow prevention assembly (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.

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.

[Image]

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:

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.

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: 

1. Have the required testing done by a licensed cross-connection technician working for a registered firm 
2. Replace the existing backflow assembly with a non-testable dual check valve and then rebuild or replace that device every five years (review the following sections for more detail). 

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: 

• Coordinate this fire sprinkler system alteration with a certified fire sprinkler contractor. The fire sprinkler contractor must verify that the design-engineered fire sprinkler system will continue to meet hydraulic and flow requirements once the backflow preventer change is complete. 
   
• Proof of coordination with a certified fire sprinkler contractor is required and shall be provided to the WSSC Water Cross-Connection Control Program. The homeowner shall be responsible for ensuring compliance with all applicable county Office of the Fire Marshal permitting and inspection requirements. 
   
• Homeowner resources for obtaining any required county permits: 
  • Montgomery County: https://www.montgomerycountymd.gov/DPS/Process/fpcc/fire-protection.html  
  • Prince George’s County: https://www.princegeorgescountymd.gov/departments-offices/permitting-inspections-and-enforcement/plan-review/building-plan-review-division/fire-life-safety-section 

[Image]

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 and yearly testing by a licensed cross-connection technician working for a registered firm is mandatory.

[Image]

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. But 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 and yearly testing by a cross-connection technician working for a registered firm is mandatory.

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 plumbingplansreview@wsscwater.com.

Understanding and respecting the risk of water contamination is a great start. When in doubt, seek help. Basic guideline: Every water outlet needs some form of backflow protection; get to know what is needed.

Have “non-testable” backflow devices maintained at the intervals described above. Have “testable” backflow assemblies tested yearly and rebuilt or replaced as needed.