Everything you need to know about backflow, why your assembly exists, what testing actually involves, and how to keep your device protecting your water year-round.
Every time you turn on a faucet, you expect clean water to come out. Normally water flows in one direction: from the public supply into your home or building. When pressure changes happen, that flow can reverse, pushing water from your property back into the drinking water supply. That reverse flow is called backflow.
Without protection, contaminants can enter the drinking water system. Fertilizers, pesticides, chemicals, standing irrigation water, industrial fluids, soil and debris, and more. A backflow preventer acts like a one-way safety gate. It allows water to move into your property but prevents anything from moving backward into the clean water supply.
Backflow protection isn't just about your house. It protects the entire public water system that serves you and your neighbors.
Backflow happens through one of two mechanisms. Both are caused by a pressure change in the system.
Happens when water pressure on the supply side suddenly drops, creating a vacuum that pulls water backward.
Example: a garden hose left in a bucket of pesticide. A nearby water main breaks and the pressure drop pulls the chemical solution back toward the line.
Happens when pressure on your side of the system becomes greater than the supply pressure, pushing water backward.
Example: a boiler running at higher pressure than the city supply forces water back toward the main.
A cross-connection is any actual or potential connection between drinking water and a non-potable source. They are everywhere, and most people have at least one on their property.
Common residential examples: lawn irrigation systems, garden hoses left in pools, chemical sprayers, water softeners, boilers, swimming pools, hose-end fertilizer systems.
Common commercial examples: chemical processing equipment, cooling towers, fire sprinkler systems, restaurants, medical equipment, manufacturing systems, soda machines, coffee makers.
Different installations call for different levels of protection. Here's what's typically used where.
A physical separation between the water supply and possible contamination. The highest level of protection because there are no moving parts to fail.
Commonly used for irrigation systems. Protects against backsiphonage but not against backpressure.
Two independent check valves in series. Used for fire sprinkler systems and lower-hazard commercial applications.
The highest level of mechanical protection. Used for high-hazard installations, chemical systems, and most commercial properties.
Click any question to expand the answer.
Backflow assemblies are mechanical devices containing springs, rubber seals, internal check valves, and relief valves. These parts wear out over time and can fail without visible signs from the outside. Annual testing confirms the device is still doing its job.
Most water authorities require annual testing. All commercial assemblies are tested annually. About half of residential assemblies are tested annually, depending on the hazard classification of the connection.
Additional testing is typically required after repairs, device replacement, relocation, or a failed inspection.
A typical test takes less than thirty minutes for most residential assemblies. We perform a visual inspection, isolate the assembly, connect calibrated test equipment, test the check valves, test the relief valve if applicable, document the results, and submit the report to your local water authority.
If the device passes, you get a copy of the report and we're done until next year. If it fails, we walk you through what's wrong and quote any repair before doing the work.
Common causes include debris in the check valves, damaged rubber seals, worn springs, freeze damage, corrosion, age, and improper installation. Most failures can be repaired without replacing the whole assembly.
Watch for water discharging continuously from the relief valve, visible leaks, reduced water pressure, chattering or vibrating sounds, standing water around the assembly, visible corrosion, or frozen piping. Any of these is a reason to schedule a test.
Minor issues can look simple, but certified testing and repair are recommended because the device protects public health. Most jurisdictions also require repairs to be performed and certified by a licensed backflow tester before the device is considered back in service.
No, we can not replace a backflow. We are licensed to test and repair backflows, but a licensed plumber or irrigator will need to actually replace a backflow that can not be fixed.
Backflow preventers protect your family, your property, the public drinking water system, and every neighbor connected to that same system. Most properties with irrigation, pools, boilers, or any cross-connection are required to have one.
Backflow devices can fail internally while looking completely normal from the outside. The only way to know it's working is to test it.
Irrigation systems commonly contain soil, fertilizer, bacteria, animal waste, and standing water. They're one of the most common contamination sources we see.
Submerged hoses are one of the most common residential cross-connection risks. A hose left in a pool, a bucket of chemicals, or a tub of dirty water can pull contaminants back into the line during a pressure drop.
Residential or commercial. Same-week scheduling. Reports filed.