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The Board of Water Supply has an annual backflow prevention assembly (BFPA) testing program in compliance with the environmental regulations of the U.S. Environmental Protection Agency (EPA), and the Hawaii State Department of Health (DOH). All major water purveyors of the State are also implementing similar testing programs that will affect many agricultural, commercial and industrial water users and high-rise and multi-family residential developments. The BFPA testing program will help to ensure that the public water system is not contaminated from the backflow of harmful substances.

Applicable Laws and Ordinances

The backflow prevention program was formulated in accordance with EPA's Safe Drinking Water Act, DOH's Title 11, Chapter 21, HRS, Cross-Connection and Backflow Control and the BWS Rules and Regulations, Section 2-213, Cross-Connection Control and Backflow Prevention. The program follows the BWS Water System Standards, and the standards of the American Water Works Association (AWWA) and University of Southern California's Foundation for Cross-Connection Control and Hydraulic Research, (USC-FCCCHR). The program's main focus is the protection of the public water system while the property's internal water system protection is addressed by the Building Department's Uniform Plumbing Code.


The BWS created the cross-connection control and backflow prevention program in the early 1970s and has been requiring the installation of these BFPA's on the property's water piping. The testing program could not be implemented until a local testing training facility could be built to train enough plumbers as certified testers. To fulfill this need, the Plumbing and Mechanical Contractors Association, (PAMCA), Local 675, constructed a training facility modeled after the USC-FCCCHR. Each tester must obtain a Certificate of Competence from either PAMCA, UCS-FCCCHR, or the Cal-Nevada Section of AWWA, which is good for three years. In addition to these training facilities, the American Backflow Prevention Association (ABPA) offers a re-certification process after a three-year period to ensure each tester is current with new test procedures and requirements.

In November 1992, the BWS finally had the tools to implement this testing program.

Typical Facilities Requiring a BFPA

Common facilities which require backflow prevention assemblies include commercial, manufacturing and industrial developments, medical facilities, hotels, high-rise buildings, shopping centers, schools, parks, golf courses, farms and both potable and non-potable irrigation systems. In addition to the facilities mentioned above, the BWS also identifies specific plumbing systems which include: make-up lines to chill water/condenser water air conditioning systems, booster pumps, trap primers, water features and swimming pool recirculation systems, boilers and chemical injection systems utilizing fire retardants and corrosion protection solutions.

BWS Cross-Connection Control and Backflow Prevention Program

The program utilizes field inspections and the review of construction plans and building permit applications to identify cross-connectional hazards, which are piping connections between the potable water system and an actual or potential source of contamination. When a cross-connectional hazard is identified, mechanical devices called BFPA's are required to be installed to isolate and contain the hazard to prevent the undesirable reverse flow of liquid or gas into the public water system. Contamination could range from a pollutional hazard with objectionable taste and color to serious health hazards leading to poisoning or the spread of disease.

There are two types of backflow conditions, which could contaminate the public water system: backsiphonage and backpressure.

  1. Backsiphonage occurs when the supply pressure at the water meter decreases below the pressure on the consumer's side. This could be caused by a water main break, water system repairs, or large fire demands. Water is siphoned into the public system, possibly drawing hazardous substances into the drinking water system.
  2. Backpressure occurs when the consumer-side pressure overcomes the normal supply pressure. This can be caused by the operation of a boiler or a separate booster pump system connected to the consumer piping. In essence, contaminated water is "pumped" back into the drinking water system.

BWS Testing Program

Oahu water consumers share the responsibility of protecting the public water system from the backflow of contaminants. All BFPA owners will be receiving test notices in the mail informing them of our annual test requirement. A series of three test notices could be mailed to the owners of the BFPA's as a means of progressive enforcement. The first notice is sent 60 days prior to the test due date which is based on the actual installation date and does not change for the life of the BFPA. The notice is accompanied by the test form, current lists of certified testers and local suppliers. The test form, which includes all pertinent BFPA information, is filled out by the certified tester, signed by the BFPA owner, then returned to the BWS indication that the BFPA is working properly.

If the test form is not received by the due date, a second notice is sent allowing 30 additional days with a reminder to comply with the testing requirement to prevent an interruption of water service. If there is no response, the staff will try to contact the responsible parties to verify the status of the testing of their BFPA. If the responsible party is unable to contract with a certified tester on their own, the BWS through its "Assistance Program" will have its certified tester test the BFPA and bill the responsible party through their water bill (or separate invoice from BWS, this invoice may include payment plan for hardship cases).

The BWS's "Assistance Program" is designed to help the customers, both private and government, who have BFPA's but are unable to comply with the Board's annual testing requirements. The program will allow the BWS to test the BFPA for the customer and bill them for this service through their water bill. (The third notice is then sent via certified mail allowing 14 additional days before service termination procedures are initiated.)

Written requests for extensions may be considered because the BWS realizes that if the BFPA fails the test, there maybe hindering factors, such as contracting and scheduling plumbing contractors to repair or replace the assembly, parts availability, and budget concerns.

Additional Information on BFPA's

There are three types of testable backflow preventers, which provide varying degrees of water system protection depending on the level of cross-connectional hazard, as determined by the BWS. These mechanical devices combine independently operating spring-loaded check valves and an air relief port that either breaks the vacuum or discharges water to atmosphere.

  • The first type is the pressure vacuum breaker (PVB) or spill resistant pressure vacuum breaker (SVB), which protects against backsiphonage, but not backpressure, and is primarily used on simple irrigation circuits. The pressure loss through the assembly averages less than 5 psi.
  • The second type of testable backflow preventer is the double check valve assembly (DC). The most common application of the DC is on irrigation systems, which use potable water exclusively, without chemical or fertilizer additives. The pressure loss averages about 5 to 10 psi.
  • The third type of testable backflow preventer is the reduced pressure principle backflow prevention assembly (RP). The RP affords the greatest degree of protection against contamination of the drinking water system and is, therefore, the most common. The RP is used for actual or potential high-risk health hazards. The pressure loss ranges from 10 to 15 psi.

The BWS maintains a list of approved backflow prevention assemblies, which it updates periodically. Approved backflow prevention assemblies must be manufactured in full conformance with the standards established by the AWWA, and must meet the laboratory and field performance specifications of the USC-FCCCHR.

How much does a BFPA cost?

The cost for a backflow prevention assembly varies by type, size and manufacturer. The BWS does not set the price of the BFPA. In addition to the initial cost of purchasing and installing the BFPA, the BFPA must be maintained and tested once annually as part of the BWS's annual testing program. The BFPA is the responsibility of the customer and therefore the customer is responsible for all costs associated with the installation, maintenance and testing of the BFPA.

What Happens When the BFPA Fails?

When the BFPA fails the test, it can either be repaired or replaced in the same relative location as long as adequate clearance, drainage (if necessary), and accessibility standards are met. By State Contractors Licensing Board Rules, only licensed plumbing contractors and licensed journeymen and master plumbers can perform repairs to backflow prevention assemblies.

BFPA owners should be made aware that there will be a pressure loss between 5 to 15 pounds per square inch, (psi), through the BFPA depending on the type. While the public water system is designed to provide adequate water pressure at the water meter, the installation of a new or different type of BFPA, may affect the property's plumbing system, especially in older high rise buildings. The owner should consult with a licensed plumbing contractor or mechanical engineer to determine if the building's plumbing system can accommodate the additional pressure loss.

Where multiple backflow prevention assemblies are installed on a single water service, the BWS requires the testing of all installed assemblies unless there is a master RP on the main line, which contains the entire development. In this case, BWS would only require the testing of the master RP. The testing of the remaining internal BFPA's would be under the jurisdiction of the Building Department.

The BWS cross-connection control and backflow prevention assembly annual testing program is administered by the BWS Cross-Connection Control Section.


Updated: 03/30/2023