Homeowner’s Handbook

Backflow Assemblies and Cross-Connection Control

Protecting the Potable Water Supply

Backflow Assemblies and Cross-Connection Control

Backflow prevention is one of the most important safety measures tied to your irrigation system, and it exists to protect the public drinking water supply. Irrigation water is considered non-potable once it enters the system because it can come into contact with fertilizers, pesticides, soil bacteria, and other contaminants. A properly installed and maintained backflow assembly helps prevent that non-potable water from reversing direction and entering the potable water system.

What Cross-Connection Control Means

A cross-connection is any physical connection between a potable water supply and a nonpotable source where contamination could occur. In an irrigation system, the crossconnection typically exists at the point where your sprinkler piping connects to the household water supply. Cross-connection control refers to the methods and devices used
to eliminate or protect that connection so the potable system stays safe. Backflow
assemblies are a key part of cross-connection control because they are designed to
prevent contaminated water from traveling backward into the drinking water system under
abnormal pressure conditions.

What a Backflow Assembly Is

A backflow assembly is a testable mechanical device installed on your irrigation system’s water supply line. Its purpose is to ensure water flows in only one direction, toward your irrigation system, while preventing reverse flow into the potable supply. Backflow assemblies are installed to meet code requirements, protect public health, and maintain compliance with local water purveyors and jurisdictions.

How Backflow Happens

Backflow can occur under two main conditions:

Back siphonage: When the supply pressure drops (such as during a mainline break, hydrant use, firefighting, or heavy municipal demand), water can be pulled backward into the potable system.
Backpressure: When downstream pressure becomes greater than supply pressure, forcing water to push backward. This can happen in certain plumbing configurations or pressure-related scenarios.

Both situations can cause contaminated irrigation water to move in the wrong direction if proper backflow protection is not installed and maintained.

How Backflow Assemblies Work

Backflow assemblies contain internal components designed to prevent reverse flow, including check valves, air inlet mechanisms, and relief components depending on the type of assembly. Under normal conditions, water flows forward as intended. If pressure conditions change and water attempts to reverse, the assembly is designed to stop that movement and protect the potable system. Because these internal parts can wear over time due to debris, mineral buildup, freezing conditions, and general use, assemblies must be tested and maintained regularly to confirm they are functioning properly.

Common Backflow Types (Treasure Valley)

Backflow devices and assemblies vary depending on system design and jurisdictional requirements. Common types include:

PVB (Pressure Vacuum Breaker): The most common backflow assembly found on residential irrigation systems.
RP / RPZ (Reduced Pressure Assembly): Typically used where a higher level of protection is required. These assemblies can discharge water as part of normal operation under certain conditions.
DCVA (Double Check Valve Assembly): Sometimes present on older or grandfathered systems, depending on local standards.
SVB (Spill-Resistant Vacuum Breaker): Less common in typical residential irrigation, but may be encountered in certain configurations, including some indoor installations.
AVB (Atmospheric Vacuum Breaker): Common on potable hose bibs and certain fixtures. AVBs are devices, not testable assemblies, and they are not tested in the same manner as PVB, RP, or DCVA assemblies.

Annual Testing and Ongoing Maintenance

Backflow assemblies should be tested annually based on your previous test date and should never exceed one year between tests. Testing can be performed early if a new schedule is preferred. Many homeowners choose to pair annual backflow testing with a system start-up, which simplifies scheduling and often allows for one visit rather than two. Testing schedules can fill quickly in peak season, so calling early or requesting placement on a recurring annual list can be beneficial. Regular maintenance matters because an assembly can appear fine externally while internal components have failed or weakened. Annual testing confirms the assembly is operating correctly and provides documentation for the appropriate jurisdiction or water purveyor when required.

Homeowner Do’s and Don’ts

Do:

Backflow can occur under two main conditions:

Keep the assembly accessible and testable at all times. Avoid blocking it with fencing, landscaping, facilities, or storage.
Maintain proper installation standards. For PVBs and similar assemblies, ensure the device remains at least 12 inches above all downstream outlets. This prevents submergence of key components that allow the assembly to operate as intended.
Keep test cocks protected using test cock caps to prevent debris intrusion.
Protect the assembly from freezing by using an insulated cover during winter and following proper winterization practices, including draining test cocks and leaving ball valves at a 45-degree position when appropriate.
Monitor the area around the assembly periodically for changes, damage, or leaking.

Don’t:

Warning Signs and When to Call a Professional

Contact a certified tester or irrigation professional promptly if you notice:

Leaks at shutoffs, unions, test cocks, or around the assembly body
Cracking, physical damage, or signs of impact
Ongoing discharge (especially on RP assemblies)
A failed annual test result that requires repair or replacement
Any concern that the device may have frozen or been damaged during winter

Maintaining your backflow assembly is not only about compliance. It is a key part of protecting your property, your system, and the shared community water supply

Introduction

The frequency of running your sprinklers in Idaho depends on several factors, including the specific needs of your lawn, soil type, weather conditions, and the type of vegetation you have. Here are some general guidelines, but it’s essential to monitor your lawn’s condition and adjust accordingly:

Grass Type:

Different grass types have varying water requirements. For example, Kentucky Bluegrass and Fescue generally require more water than drought-tolerant varieties like Buffalo grass.

Soil Type:

The soil composition influences water retention. Sandy soil drains quickly and may need more frequent watering, while clay soil retains water longer.

Weather Conditions:

Monitor weather patterns, including temperature and precipitation. Cooler temperatures and overcast days require less watering than hot and sunny days.

Watering Depth:

Water deeply and infrequently to encourage deep root growth. Most lawns benefit from about 1 to 1.5 inches of water per week, including rainfall.

Morning Watering:

Watering in the early morning allows for optimal absorption and minimizes water loss due to evaporation.

Adjust for Rainfall:

If there's significant rainfall, adjust your irrigation schedule to avoid overwatering. Many modern sprinkler systems have rain sensors to automatically adjust watering schedules.

Check Soil Moisture:

Use a soil moisture sensor or manually check the soil moisture level. If the top inch or two of soil is dry, it's generally time to water.

New Plantings:

Newly planted areas may require more frequent watering until they are established.

Seasonal Watering Durations

Adjusting your sprinkler run times according to the seasons ensures optimal watering for your lawn and garden, promoting healthy growth and efficient water usage. Remember to monitor local weather conditions and make further adjustments as needed.

Spring Sprinkler System Activation Guide: Ensuring a Smooth Start

Check for Freezing Temperatures:

Before activating your sprinkler system, verify there are no impending freezing temperatures in the forecast. A hard freeze can cause damage to sprinkler heads and underground pipes. In Idaho, it’s generally safe to turn on the system by early to mid-March.

Sprinkler System Blowout Protocol for Yearly Maintenance: Ensuring Longevity

Blowing out your sprinkler system annually is a crucial step in maintaining its health and longevity. This process is particularly vital before freezing temperatures set in to prevent potential damage caused by frozen water within the pipes or sprinkler heads.

Homeowner’s Handbook