San Francisco Backflow Program

Cross-Connection Control Program

The City and County of San Francisco has a cross-connection control program to protect the City’s drinking water distribution system from contamination caused by backflow. This program was established through the City’s Backflow Prevention Ordinance, adopted in 1984. Under normal conditions, water from the distribution system flows into a consumer’s premises. When backflow occurs, water from the consumer’s premises flows into the distribution system. If that water is contaminated because of activities on the consumer’s premises (for example, addition of rust-inhibiting chemicals to a boiler or use of photo-processing chemicals), the water can carry contaminants into the distribution system, possibly causing illness or even death. 

The City’s cross-connection control program is administered by the Water Quality Division of SFPUC. 

Cross-Connection Control (Backflow Prevention) At a Glance

To protect the City’s drinking water system from contamination caused by backflow. 

Who Must Comply? 
Owners of properties with potential unprotected cross connections and/or backflow prevention assemblies. 

Municipal Code 
Health Code, Article 12A 

Rules and Regulations Governing Water Services to Customers: Section G - Cross-Connection Control

See our frequently asked questions

Cross-Connection Control Program 
(650) 652-3199 

Do the requirements apply to me?

If your property has a potential cross-connection or hazard (for example, boiler, chemical feed equipment, dedicated irrigation, an interconnected fire sprinkler system, or building height 40 or more feet above the point of connection/water meter), then the requirements of the Backflow Prevention Ordinance apply to you. You are required to install an approved backflow prevention assembly and have it tested annually. 

If you are a backflow prevention assembly tester, scroll down further on this web page to “I’m a backflow prevention assembly tester.”

How do I comply?

All potential cross-connections must be protected with an approved backflow prevention assembly. To be approved for use in San Francisco, an assembly must be on the “Approved Backflow Prevention Assemblies” list developed by the University of Southern California Foundation for Cross-Connection Control and Hydraulic Research. The assembly may not be modified or installed in a manner that differs from the configuration tested and approved. New assemblies must be tested immediately after installation and once a year thereafter. After the initial test, Water Quality Division will send you a notice when annual testing is due. All testing must be performed by an authorized backflow prevention assembly tester. 
For additional information about backflow prevention, see the Consumer Guide to Backflow Prevention and other resources listed at the bottom of this web page.

I’m a backflow prevention assembly tester. What do I need to know?

Testers must be permitted by the Department of Public Health. Certification requirements are listed on its website.

What to do if your water is compromised in a natural disaster

What to do if your water is compromised in a natural disaster

Backflow Testing

San Francisco Maritime Museum


Backflow testing at the historical San Francisco Maritime Museum.

The Maritime Museum (above)  was until recently housed in a Streamline Moderne (late Art Deco) building that is the centerpiece of the Aquatic Park Historic District, a National Historic Landmark at the foot of Polk Street and a minute's walk from the visitor center and Hyde Street Pier. The building was originally built (starting in 1936) by the WPA as a public bathhouse, and its interior is decorated with fantastic and colorful murals,

Click on picture for slide show

Alameda Point Water Quality Alert

Alameda Point Water Quality Alert

Backflow Testing

A little Backflow Prevention history

Most people don't know that complicated irrigation systems have been around since ancient civilizations, beginning with Babylon and Rome, as they developed intricate networks of aqueducts to keep their water system clean. 

Let's go through a brief timeline of how modern age developed and eventually mandated backflow devices be used to protect our water system.

-In 1906 ASSE (American Society of Sanitary Engineering) was formed, based on their motto "Prevention Rather Than Cure".  In the spirit of their motto, this organization strives to continually improve the performance, reliability and safety of plumbing systems.  ASSE maintains nearly 50 product performance standards, including those regarding double check and reduced pressure backflow preventers, with many more still in the development stage.

-The paper "Secondary Water Supplies, Their Danger and Values" was presented at a 1910 New England Water Works Association meeting which discussed the many cases where secondary supplies contaminated the water distribution system.  The typical type of check valve at that time was leading to very limited backflow protection.  This led to a change in installation standards.

-In 1912, the United States Congress passed the Public Health Service Act, which authorized surveys and studies for water pollution on public health. 

-At the 1933 World's Fair in Chicago, an improperly designed plumbing system caused a backflow incident to occur.  1,409 people came down with amoebic dysentery and 98 deaths. This tragedy made it clear the need for cross connection control.

-In 1944, because of continuing backflow issues surrounding a healthy water supply, a group of concerned individuals approached the University of Southern California to conduct research in this area as they already had training courses and a laboratory constructed dedicated to the protection of potable water supplies.  The USC Board of Trustees established the Foundation for Cross-Connection Control Research. 

-The Uniform Plumbing Code was formed in 1945 establishing codes and product standards to address the needs of the public and plumbing /mechanical communities.  The newest version was published in 2015 and is the most widely used guide for backflow preventer installation.

-In 1956 the Standard Plumbing Code was established, which is now the International Plumbing code. 

-In 1973 the Environmental Protection Agency published their first edition of the Cross-Connection Control Manual.  This manual is designed as a tool for health officials, waterworks personnel, plumbers, and any others involved directly or indirectly in water supply distribution systems.

-The Safe Drinking Water Act was enacted into law in 1974 and focuses on ensuring that public drinking water meets appropriate safety standards.  Under this Act that was proposed by President Nixon, the EPA retains oversight of the nations' drinking water.

-In 1976 the AWWA filed it's articles of incorporation with a purpose to promote public health, safety, and welfare through the improvement of the quality and quantity of water delivered to the public.  This group of men representing water utilities originally met in 1881 and later became reframed as the AWWA.

-2017 As you can see we have come a long way with regulations, laws, and industry standards in regards to the safety of our potable water systems.  It is up to each water jurisdiction to continue to regulate and mandate the laws and codes that currently keep our water safe.