Backflow prevention and cross-connection control

We depend on property owners to protect our community's health by installing backflow prevention assemblies where required. State law and City Code require these assemblies on properties with irrigation systems, fire sprinkler systems, or other cross-connection risks. Property owners are responsible for keeping their assemblies in working order and getting them tested each year.

Cross connections and backflow

A cross connection is any place where the pipes that carry drinking water connect with sources of water or other substances that are not safe to drink. Hot tubs, irrigation systems, and fire sprinkler systems are common cross connections. Cross connections can also be temporary, like a garden hose submerged in a bucket or a chemical spray attachment for a hose.

Backflow happens when water flows through pipes in the wrong direction. Water normally flows through our drinking water system in only one direction: from the public water system to plumbing at homes and businesses. But sometimes a change in water pressure can push or pull the water in reverse, so it flows back into the water system.

You can simulate backflow when drinking water through a straw. First, pull water into your mouth. Then, instead of swallowing, blow or push the water back through the straw and into the glass. Backflow can happen in the same way and can pull or push used or unsafe water back into the drinking water supply.

When backflow happens at a cross connection, it's a public health concern. Chemicals, fertilizers, or other contaminants can be pulled or pushed back into the drinking water system and show up at your or your neighbors' taps.

Fortunately, you can prevent unsafe water from entering our water system with an approved backflow prevention assembly. To protect our water, we require many businesses and homes to have backflow prevention assemblies.

View full size image of diagram showing that backflow prevention assemblies keep contaminants from flowing back into the public drinking water supply from other systems

Backflow prevention assembly requirements

Backflow prevention assemblies make sure backflow from cross connections won't harm our community's health. These devices allow water to flow in only one direction, so contaminants can't flow back into the drinking water supply.

Our backflow and cross-connection control program is one way we work to keep your water safe, but we can't do it alone! We depend on property owners to install needed backflow prevention and keep up with proper testing and maintenance. 

Which properties need backflow prevention

Many commercial properties and some residential properties need backflow prevention. If your property has an existing or potential cross connection, you must install a backflow prevention assembly. State of Oregon law and City of Portland rules specify when a property needs backflow prevention. They also list requirements for installing backflow prevention assemblies.

You may need a backflow prevention assembly if your property has a:

• Lawn irrigation system
• Fire sprinkler system
• Water feature (like a fountain or fishpond)
• Swimming pool, hot tub, or spa
• Solar heating system
• Private well or any alternate water supply
• Boiler system

Many types of commercial properties need backflow prevention assemblies. These include, but are not limited to:

• Multi-tenant or mixed-use properties
• Car washes
• Commercial laundries or dry cleaners
• Food processing plants
• Medical centers
• Properties where the water is treated with chemicals or other additives

If you're unsure whether you need to install a backflow prevention assembly, contact us at backflow@portlandoregon.gov or 503-823-3256.

How to tell if you have a backflow prevention assembly

If your irrigation system, fire sprinkler system, pool, or other fixture was permitted through the City of Portland, proper backflow protection was required.

View full size image of A water meter box embedded in the ground behind a street curb with a second in-ground box just behind that with a green lid labeled "irrigation control valve"

If you believe a system or fixture was installed without permits, you should check for a backflow prevention assembly. At residential properties, irrigation backflow prevention assemblies are usually found near your water meter box. Look for a small in-ground box with a green lid, sometimes marked "sprinkler system." Fire system backflow prevention assemblies are usually installed in a mechanical room, closet, or garage.

If you can't find your backflow prevention assembly but think your property may need one, contact backflow@portlandoregon.gov or 503-823-3256. We're here to help.

Installing, testing, and maintaining backflow prevention assemblies

Property owners are responsible for installing, testing, and maintaining required backflow prevention assemblies. Contact the Portland Water Bureau at backflow@portlandoregon.gov or 503-823-3256 before installing, removing, replacing, or relocating an assembly.

Installing a backflow prevention assembly

Before installing a backflow prevention assembly, you must:

• Notify the Portland Water Bureau at backflow@portlandoregon.gov or 503-823-3256
• Get any required trade permits through Portland Permitting & Development

Only buy backflow prevention assemblies approved by the Oregon Health Authority. Approved assemblies should be installed by a licensed contractor.

After installation, you must get your backflow prevention assembly tested by a state-certified backflow assembly tester. Once we receive your initial test report, we will update our records. You will then start receiving annual testing reminders.

Testing rules and requirements

Backflow prevention assemblies must be tested each year by a state-certified backflow assembly tester. Property owners are responsible for scheduling the test and making sure their assemblies work.

Learn more about the testing process

Maintenance and repair of backflow prevention assemblies

To protect our drinking water system, it's important to keep your backflow prevention assembly in good working condition.

If your backflow prevention assembly needs maintenance or repair, contact a licensed plumber. For assemblies on irrigation systems, you can arrange for repairs with a landscaper licensed by the Oregon Landscape Contractors Board. You do not need to notify the Portland Water Bureau before scheduling maintenance and repairs. You must get your assembly tested again after any repairs.

If your backflow prevention assembly needs to be replaced, you must first get approval from the Portland Water Bureau. Please contact us at backflow@portlandoregon.gov or 503-823-3256.

Removing a backflow prevention assembly

If you want to remove your assembly, the Portland Water Bureau must verify that your water use on the property no longer poses a backflow risk. You may also need a permit through Portland Permitting & Development. Please contact us at backflow@portlandoregon.gov or 503-823-3256 for more information.