Backflow Testing & Prevention
Check the device that keeps irrigation water from flowing backward into drinking water.
Plumbing guide
Backflow Preventer for Irrigation in Fountain Hills, AZ
Water is meant to flow one way, from the supply to your taps. A backflow preventer keeps contaminated water from flowing the other way when pressure drops. It is a small device with a large job.
By the Fountain Hills Rapid Plumbing team ·
What backflow is
Backflow begins when supply pressure falls, say during a main break or heavy hydrant use, and water gets drawn the wrong way. A hose in a bucket of fertilizer, or an irrigation line in a puddle, can then draw contamination into the pipes.
A preventer is a valve assembly built to stop water from reversing direction. It is required on many irrigation systems, fire lines and commercial connections.
Types of devices
Simple hose bib vacuum breakers screw onto outdoor faucets. Sprinkler lines commonly get a double check valve or a pressure-type vacuum breaker. Connections with greater contamination risk get a reduced pressure assembly, whose relief port spills water when a part fails.
The right device for a property follows from the hazard level and local rules. The utility or the town can say what applies to your address.
Device types in plain terms
The right device depends on the hazard.
| Device | Where it is used | Note |
|---|---|---|
| Spigot vacuum breaker | Outdoor faucets | Threads onto the faucet |
| Pressure-type breaker | Sprinkler lines | Mounted higher than every sprinkler head |
| Dual check assembly | Lines with modest contamination risk | Needs periodic testing |
| Reduced pressure assembly | Higher-hazard lines | Has a relief port that may discharge |
Why testing matters
Backflow devices have springs and seals that wear out. A failed device looks fine from the outside. Many water providers require periodic testing by a certified tester, and the report is sent to the utility.
Ask your provider which assemblies on your property need annual testing, and who is allowed to perform it. Details of a testing visit are on the backflow testing page.
Signs of trouble
Water spraying from the relief port of a reduced pressure device, a device that leaks after irrigation cycles, or a drop in pressure after the device is installed all point to a fault. Frozen or sun-damaged plastic housings can crack.
Never cap a relief port to stop the dripping. It is the safety feature.
Installation details
Devices must be installed at a set height above the highest sprinkler head, with room for testing and with the right orientation. Some are installed above ground in a box that is protected from freezing.
Replacing a failed unit usually takes a single visit. Include test fittings in the plan so the next test is simple.
Pools, spas and alternative sources
A pool fill line, a spa and a fire sprinkler system can each need protection. An outdoor kitchen with a hose and a sprayer is another. Ask a plumber to walk the property and list the cross-connections.
If your property has a private well or tank, cross-connection with the house supply must be prevented. Tell the dispatcher about any non-utility sources.
Choosing a tester
Ask for a tester who holds the certification your water provider accepts, and ask whether the report is filed for you. Some providers keep an approved list, so check before you hire.
Get the test and any repair quoted separately. A simple rubber part swap is routine, and a full assembly replacement is a different job.
What happens at the utility end
Water providers keep a list of assemblies that need annual testing and send reminders or notices. If you move into a house with an irrigation system, ask the previous owner or the provider whether a device is on file. Unregistered devices and missed tests are a common reason for a notice.
If a notice arrives, do not ignore it. A passing report from a certified tester usually settles the matter, and a failed one can be repaired and retested.
Selling or buying a house with a sprinkler system
Buyers often ask whether the irrigation backflow device has been tested. A recent report is easy to hand over and shows that the system has been looked after. If there is no report, a test before listing avoids a surprise during the sale.
If you are the buyer, look for the device near the front of the house or by the meter, and ask for the last report. A corroded or leaking assembly is a negotiating point.
Mistakes that cause failures
Installing the device too low lets sprinkler heads sit above it, which defeats the purpose. Burying it in a box that floods with runoff exposes it to dirty water. Letting a landscaping crew cover or damage it can crack the housing.
Freezing nights can split a device that holds water. At this elevation the risk is small but real, so an insulated cover is cheap protection.
Paperwork and records
Keep the installation record, serial number and each test report in one folder. A utility may ask for these when you sell the house or request a new meter. A missing report can delay a service request.
Record the date of each test and the date of the next one. Set a calendar reminder so the test does not lapse.
Protect the device from sun and damage
Backflow devices sit outdoors and take heat, impacts from landscaping crews and sometimes theft of brass parts. A shade cover or a lockable enclosure helps.
Keep the area around the device clear so a tester can reach it. Avoid burying it in mulch or rock.
Who to call
A plumber can install and repair a backflow device, and a certified tester performs the annual test. Many do both. Keep the test report with your records, since the utility may ask for it.
The leak guide on outdoor spigots covers the small vacuum breakers on hose bibs.
Common questions
Backflow questions
Nearly all sprinkler systems need one. Your utility or town can say what your address requires.
Many providers ask for an annual test. Ask yours.
A reduced pressure device may discharge when it detects a problem. Call for service.
Testing needs certified gear and a certified tester in most places.
Related services
Leak Detection
Find where hidden water is escaping, whether it is behind a wall, under a floor or along the buried line.
Commercial Plumbing
Plumbing help for shops, offices, restaurants and buildings that house several tenants.
More plumbing guides
A hose bib that drips
A leaking outdoor faucet wastes water and may hide something worse, so find out where the drip starts.
The bucket test for pool leaks
A bucket on the pool step shows whether the water is evaporating or escaping, and the test costs nothing.
Why bills run high
When the bill jumps, the culprit is usually a leak, an irrigation setting or a change in how the house is used.
Backflow device leaking or due for a test?
Describe the device and its condition, and the dispatcher points you to a tester.