Golden State Water Company (GSWC) is committed to providing our customers with water that meets all state and federal drinking water standards. This precious resource, once it enters businesses and homes, gets used in many ways; some of which may pose a potential contamination risk to the water supply. Ensuring that the integrity of our community water supply is maintained in the systems is therefore a responsibility that GSWC must also extend to you, our customer. Together, we can proactively safeguard the water system by preventing plumbing setups that may result in the water’s contamination.

Program Overview

Golden State Water Company’s Cross-Connection Control Program:

• Safeguards our community’s drinking water by identifying and mitigating potential and/or existing cross-connection hazards at customer premises.
• Provides information on how customers can protect and safeguard the public water system from unwanted backflow and cross-connections.  
• Ensures backflow assemblies in the water system meet all state regulatory requirements.

Defining Cross-Connection

Cross connections are plumbing setups that can provide a direct pathway for contaminated substances to enter the water supply. The most common cross-connection in a residential setting is a water hose with the inlet left submerged in a container containing a contaminated substance.

Understanding Backflow, Backsiphonage, And Backpressure

In an ideal world, water would flow only from the public water system into customer homes and businesses. The reality, however, is that, under the right conditions, water that has made its way into customer plumbing systems can return to the public water system. When this flow reversal occurs, it is referred to as backflow.

There are (2) hydraulic conditions that can cause backflow:

1. Backpressure: Occurs when water pressure in the customer plumbing system exceeds the public water system pressure.
2. Backsiphonage: Occurs when the pressure in the public water system suddenly decreases. Pressure can suddenly drop during a firefighting event, a broken water main, or other high water demands by end users.

Why It Matters

Cross-connections are a public health concern because any water reintroduced into the public water system can potentially carry contaminants with it. In this way, cross-connections can compromise the quality of the public water supply.

Taking Measures To Protect The Water Supply

Backflow prevention assemblies, installed downstream of the water meter, offer GSWC a mechanism for ensuring contaminated water does not flow back into the public water system. They act as check valves that allow water to flow only in one direction; from the public water system into homes and businesses.

Not all backflow assemblies are created equal, with some offering higher protection than others. If GSWC requires installing a backflow assembly, the water user will be provided with a letter indicating the type of backflow prevention assembly/method that needs to be installed/implemented.

Approved Assembly Types & Method For Backflow Prevention

Pressure Vacuum Breaker Assembly (PVB)

This backflow prevention assembly contains a check valve and an independently operating loaded air inlet valve. It is designed to protect against non-health hazards and health hazards under backsiphonage hydraulic conditions only.

Double Check (DC) Backflow Prevention Assembly 

This backflow prevention assembly has two independently acting check valves in series. It is designed to protect against non-health hazards under a backpressure or back-siphonage hydraulic condition.

Double Check Detector Assembly (DCDA)

A Double Check (DC) assembly, with an approved bypass line. The bypass line is equipped with a DC assembly and a water meter. The meter is included to detect leaks and unauthorized taps in the customer plumbing system. This backflow prevention assembly type is commonly used in fire protection systems posing a non-health hazard to the public water supply.

Reduced Pressure Principle (RP) Backflow Prevention Assembly

This backflow prevention assembly contains two check valves and a differential relief valve. It is designed to protect against non-health and health hazards under backpressure and back-siphonage hydraulic conditions.

Reduced Pressure Principle Detector Assembly (RPDA)

A Reduce Pressure Principle (RP) assembly, with an approved bypass line. The bypass line is also equipped with an RP assembly and a water meter. The meter is included to detects leaks and unauthorized taps in the customer’s plumbing system. This backflow prevention assembly type is commonly used in fire protection systems posing a health hazard to the public water supply.

The Air Gap (An Approved Backflow Prevention Method)

The most effective form of backflow prevention is the air gap—a physical separation between a water supply outlet and the highest potential water level in a receiving vessel. The air gap eliminates the possibility of backflow due to the absence of a direct connection to the piping. The physical separation is a vertical distance specified by regulations.

Non-Testable Backflow Prevention Device Hose Bib Vacuum Breaker

The hose bib vacuum breaker is a special application of an atmospheric vacuum breaker. These devices are inexpensive, easy to install, and provide a basic level of backflow prevention against backsiphonage hydraulic conditions only. GSWC advises installing these devices on every fixture where a hose connection can be made on your premise. Installation and operation guidelines for the hose bib vacuum breaker can be found in the California Plumbing Code.

Customer Responsibilities

• Install and maintain backflow preventer assemblies as required by GSWC.
• Ensure that backflow prevention assemblies are tested annually by a certified tester and test results are submitted to GSWC in good time. In specific cases, GSWC may require a higher testing frequency on an backflow prevention assembly.
• Report to GSWC’s Cross-Connection Control Program any changes in water usage activities or plumbing within their premise that may introduce or alter cross-connection risks. Please email backflowtest@gswater.com or call 1-800-999-4033.

Company Responsibilities

• Identify cross-connection hazards by conducting hazard assessments of customer premises and ensure that identified hazards are effectively eliminated/mitigated.
• Provide information and guidance on how to install and maintain backflow assemblies.
• Ensure adherence to backflow prevention regulations.
• Uphold the safety and reliability of the water being supplied to our customers.

Indicators of Backflow Incidents

• Backflow incidents can jeopardize public health. Key indicators that a backflow incident has occurred may include:
  • Unusual water odor or taste
  • Water discoloration
  • Sudden water pressure changes
  • Physical illness after consuming tap water

Below is a list of commonly asked questions about cross-connections, backflow prevention assemblies, and annual testing requirements. If you require additional assistance, email backflowtest@gswater.com.

Frequently Asked Questions

Why do I need a backflow prevention assembly installed at my meter? 

State regulations require certain premises and business types to install backflow assemblies.  For those not explicitly required, a hazard assessment is conducted to determine if a backflow assembly is necessary to safeguard the public water supply from potential or actual contamination.

How can I prevent backflow and potential contamination?

Backflow prevention assemblies, such as reduced pressure principle or double-check backflow prevention assemblies, are crucial safeguards against water contamination. They prevent unwanted backflow, reducing the risk of potential harm to the water supply. Golden State Water Company has adopted standard specifications for installing backflow prevention assemblies.

How can I find a Certified Backflow Prevention Assembly (BFA) and Tester?

Golden State Water Company cannot recommend testers, nor do we maintain a list of certified testers. If you need a tester:

• Consult with your current plumber or contractor. These professionals usually hold backflow tester certification or know someone who can test your assembly.
• PLEASE NOTE: Whomever you select to test your BFA must be certified to do so. You should confirm that the plumber or contractor you select as a tester is certified. Testers must hold a current certification from the county, the American Backflow Prevention Association (ABPA), or the American Water Works Association (AWWA). Don’t hesitate to contact us if you are uncertain if your tester’s certification is acceptable.
• Search online using keywords such as “Backflow”, “Testers”, “Cross-Connection”, etc.
• Check your assembly. In some cases, the existing BFA has been tested before and would have a tag from the previous tester that shows the tester/ testing company’s phone number.

The backflow tester should use the annual test form supplied by Golden State Water Company, since it is pre-populated with unique identification numbers. If it is not available, the tester may use this approved blank form.

Where can I find additional resources? 

EPA Cross Connection Control Manual
Rule 16: Service Connections, Meters, and Customer’s Facilities
Division of Drinking Water Cross Connection Control Policy Handbook
List of Approved Backflow Prevention Assemblies
Change of Mailing Address Request Form

P-35 Backflow Prevention Assembly Overview for Above Ground Installation
P-35-Backflow-Prevention Assembly for Fire Services Standard Drawing