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Cross-Connection Control

Cross-Connection and Backflow Regulations

Federal and state laws require all customers and public water suppliers to take adequate measures to protect our drinking water system from the contamination that can occur through unintentional backflow, or the reversal of flow in water from the treatment plant to the customer. Backflow can create health hazards through "cross-connections," when contaminated water makes a connection to your water supply system.

Backflow may occur if the drinking water system suddenly loses pressure when, for example:

  • Large quantities of water are pulled from the system to fight a fire
  • There is a break in the water distribution pipeline

For Residents

The City is conducting field inspections for backflow hazards. If inspectors identify an issue on your property, you will be notified.

Residential Requirements
Irrigation System Requirements
Backflow Installers and Testers - list of approved contractors

For Businesses

Commercial Requirements
Potential Cross-Connection Sites

For Testers

City of Sunnyvale Cross-Connection Control Program Policies and Regulations
Backflow Device Test Form
New Assembly Installation Report Form
Backflow Device Standard Detail Drawings
Application Packet

For Private Well Owners

Though not tested by governmental agencies, private wells can still pose a hazard to the drinking water system and must be equipped with proper backflow prevention devices.

Water District Information for Well Owners

How Can I Find Out if I am in Compliance?

Through its Sunnyvale Water Distribution Cross-Connection Program, the City works with consumers, architects, contractors and engineers to ensure that backflow prevention devices are incorporated into project plans, installed correctly and maintained and tested annually.

The City also conducts free inspections to help residents and business owners determine whether they are in compliance. To arrange a City inspection:

If you need a backflow device, the City will notify you within 30 days with a letter included with your utility bill.

Your water service may be disconnected if you fail to comply with our requirements after repeated requests from the Sunnyvale Water Program.

How to Prevent Backflow Situations

  • Be aware of cross-connections, eliminate or isolate them.
  • Maintain air gaps on sinks and when using hoses.
  • Do not submerge hoses or place them where they could become submerged.
  • Use hose bib vacuum breakers on fixtures (hose connections in the basement, laundry room, and on outside faucets).
  • Install approved backflow prevention devices on lawn irrigation systems and on fire sprinkler systems.
Last Updated: Apr 2, 2019
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