Cross Connection Prevention

Take these steps to help protect our community's water supply!

If you would like more information or have any questions, please contact the City's Water Resource Management program staff at 650-780-7436.

“I have a well or use creek water for irrigation on my property - why do I need a permit and backflow prevention device?"

Redwood City’s drinking water is all from the Hetch Hetchy water system, direct from the Sierra Nevada Mountains, and it’s well known that it’s some of the best, purest water in the world! We’re very fortunate to have access to this world-class water supply. That’s one reason why it’s so important to be sure that our water system is maintained in top condition, and that we avoid the possibility of contamination. Another reason is that it is State and City law.

~ Step 1 ~

• Do you have a groundwater well or a creek on your property?
• Are you using one of those water sources for your landscape irrigation?

A well on your property (whether it’s in use or not), OR the use of creek water for irrigation, requires a permit from the City. If the water is being used, then a backflow prevention device is also required to ensure there is no cross connection. A cross connection is when untested well water or creek water is allowed to mix into the City’s drinking water distribution system.

Redwood City's Cross Connection Control Ordinance is in place to prevent such an occurrence (and which is required by the State and already enforced in other neighboring communities). This web page has information on how to bring your property into compliance with cross connection control requirements.

~ Step 2 ~

"What type of backflow prevention device do I need?"

~ Step 3 ~

"What if my well is inoperable?"

You have a well on your site that is NOT operational Your well no longer has any plumbing attached to it

Instead of a backflow assembly at the meter, the City will perform annual inspections to verify non-use. Apply for a permit to begin this process.

Note: Every backflow assembly in the City must be tested by a Certified Backflow Prevention Tester every year to make sure it is working properly.

Types of backflow prevention devices

A Reduced Pressure Principle Backflow Assembly (RP) provides the highest protection and is needed when the chance of contaminated water reaching the city’s drinking water supply is the most possible.  It has triple layers of protection with two check valves and an air relief valve to stop water from moving backwards.  The RP needs to be installed above ground because of the air relief valve, if the air relief valve were submerged in a box it could suck dirty water that could be surrounding it into the water lines. This assembly comes with test ports that make it easy to test so we know that it is working properly. 

Click here for information on installing an RP device

A Double Check Valve Assembly (DC) has two layers of protection with only two check vales.  If a check valve fails, you have a back up to support it.  With no air relief valve this assembly can be installed below grade in a box but it is important to make sure the box is big enough to allow room for testing the assembly to make sure it is working and for any needed repairs. Use of a DC must be approved by the City following an inspection - please note that there is a fee for this inspection.

Click here for information on installing a DC device

For a Non-Operation Well Inspection - Staff will visit your property and inspect your well site.  When it is clear that the well is truly inoperable the City will issue you a report stating that you have complied with requirements for that year. A well inspection will need to be performed every year or until the customer decides to use the well or permanently destroy the well.

Click here if for information on getting an
inspection of your non-operable well

~ Step 5 ~

"How do I apply for a permit?"

There are two ways to apply for a well permit through Redwood City's Building and Inspection Division:

• Visit the Permit Counter at the Building and Inspection Department at City Hall located at 1017 Middlefield Road between the hours of 7 am – 5 pm.
• Apply for the well permit online at www.redwoodcity.org/wellpermit.  Upon completion of the form, print and mail to the Permit counter or email the completed form to permits@redwoodcity.org.

For a Limited Time Only! No City Fees for Compliance!

Take advantage of the City’s Amnesty Program by letting the City know about your well or creek water usage, and take action to protect your site and the community’s water supply. City-related backflow installation costs will be waived until January 28, 2014. This includes the fees below:

• Well Permit/Plumbing Fee $50
• Backflow Preventer Registration Fee $60
• Backflow Preventer Filing Administration Fee $60
• First test your backflow preventer (free upon request) $60

That's a savings of over $200!