Backflow is one of those plumbing issues most homeowners never think about — until they're told their water supply has been contaminated. A backflow preventer is the device that stops contaminated water from flowing backward into your clean water supply. In Las Vegas, certain properties are required by Clark County to have them tested annually. Here's what you need to know.
What Is Backflow?
Backflow occurs when water flows in the wrong direction — backward from a contaminated source into the clean drinking water supply. This can happen when there's a sudden pressure drop in the water main (from a water main break, heavy firefighting demand, or rapid valve shutoff), creating a vacuum that sucks water backward from irrigation systems, pools, or other sources into the supply line.
The contamination risk is real: irrigation water containing fertilizer, pesticides, and soil can enter your drinking water if backflow isn't prevented. So can pool chemicals, gray water, and other hazardous substances.
Types of Backflow Preventers
- Pressure vacuum breaker (PVB) — The most common type for residential irrigation systems. Installed above ground at least 12 inches above the highest irrigation head. Must be replaced, not repaired, when it fails.
- Reduced pressure zone device (RPZ) — Used for higher-hazard applications like commercial properties, pools, and fire suppression systems. More complex and more reliable.
- Atmospheric vacuum breaker (AVB) — Used on individual hose bibs and irrigation valves. Simple and inexpensive but must be installed in specific configurations to work correctly.
Clark County requirement: Properties with irrigation systems, pools, or other cross-connections are required to have their backflow preventers tested annually by a certified tester. Smith's is a certified tester and can handle your annual compliance testing, repair failed devices, and install new assemblies.
Signs Your Backflow Preventer Is Failing
- Dripping or leaking from the device even when irrigation is off
- Failed annual test (the tester gives you a report showing it didn't hold)
- Visible corrosion or damage on the assembly
- Water pressure noticeably different after the device was installed
Installation: When You Need One
Any new irrigation system installed in Clark County requires a backflow preventer as part of code compliance. Adding a pool, spa, or any connection that could contaminate the water supply also triggers the requirement. We install the correct type for your application and ensure it passes initial inspection.
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Frequently Asked Questions
What is a backflow preventer and do I need one?
A backflow preventer stops contaminated water from flowing backward into your clean water supply. In Clark County, properties with irrigation systems, pools, or other cross-connections are required to have them installed and tested annually.
How often does a backflow preventer need to be tested in Las Vegas?
Clark County requires annual testing by a certified backflow tester. After the test, the tester submits results to the water authority. Smith's is certified and handles the testing, repair, and installation.
Can a backflow preventer be repaired?
Some types (like RPZ devices) can be repaired by replacing internal components. Others (like pressure vacuum breakers) are typically replaced rather than repaired when they fail a test. Smith's will tell you which applies to your device.
What happens if my backflow preventer fails its test?
A failed test means the device is not providing adequate protection. The water authority will typically require you to have it repaired or replaced and retested within a set timeframe. Smith's can handle the repair and retest in one visit.