Backflow Preventer Testing in Colorado: What It Is and Why Your Town Requires It

A backflow preventer is a valve on your irrigation system that stops sprinkler water from flowing backward into your drinking water supply. Colorado state law and most Front Range municipalities, including Erie, Longmont, Louisville, and Lafayette, require annual backflow testing by a certified tester. Testing typically costs $50-$75 and takes about 15 minutes.

What a Backflow Preventer Does

In plain English: it's a one-way gate that keeps irrigation water from flowing backwards into your drinking water supply.

Here's why that matters. Your sprinkler system is connected to your home's water line. When the system runs, water flows out to your yard. But if there's a sudden pressure drop in the city water main (say, a fire hydrant gets opened or a main breaks), suction can pull water backwards through your pipes. That means fertilizer, pesticides, dirt, and whatever else is in your irrigation lines could get sucked into the city's drinking water supply.

The backflow preventer stops that from happening. It's a safety device. And it's required by Colorado plumbing code on every irrigation system.

Why Colorado Requires Annual Testing

It's not enough to have one installed. The state and most local municipalities require it to be tested every year by a certified tester. The Town of Erie, City of Longmont, Louisville, Lafayette, and most Weld County water providers all enforce this.

What happens if you skip it? You'll get a notice from your water provider. Then another one. Then potentially a fine, and in some cases they can shut off your water service until you get compliant. Erie and Longmont both send annual reminders and follow up if you don't submit test results.

Most towns require the test to be completed in spring, typically by May or June. Check with your specific water provider for the deadline.

What the Test Involves

The test itself is quick and straightforward:

• A certified backflow tester comes to your property (this has to be someone with a current Colorado backflow testing certification)
• They hook up a differential pressure gauge to the test ports on your device
• They run a series of pressure tests that take about 10-15 minutes
• They fill out a test report and submit it to your water provider
• Cost: $50-$75 in our area, sometimes bundled with your spring startup

You don't need to be home for the test as long as the tester can access the device. Most backflow preventers are on the exterior of the house.

Common Problems We Find

When a backflow preventer fails its annual test, here's what's usually going on:

Internal seals are worn. The check valves and relief valve inside the device have rubber seals that wear out over time. This is the most common failure. Rebuilding the internals costs $100-$200 depending on the model. It's normal maintenance, not a disaster.

Freeze damage. This is the big one in Colorado. If your backflow preventer wasn't properly winterized and water sat in it over the winter, the internal components can crack. A freeze-damaged preventer usually needs to be replaced entirely. That's $300-$600 installed, depending on the model and size. This is why winterization matters.

Debris in the valve. Sand, pebbles, or pipe sediment can get caught in the check valve and prevent it from sealing properly. Sometimes a good cleaning fixes it. Sometimes the parts need replacing.

The device is just old. Backflow preventers last 15-25 years with good maintenance. If yours is original to the house and the house is 20+ years old, you might be due for a replacement.

Can You Test It Yourself?

No. Colorado requires testing by a certified backflow prevention assembly tester. You can't test it yourself and submit the results.

But here's what you can do on your own:

• Visual inspection. Look at it in spring before you turn on your system. Any visible cracks, rust, or leaking from the test ports? That's a sign it needs attention before testing.
• Check for leaks during operation. When your sprinklers are running, walk past the backflow preventer. Water dripping or spraying from it means something isn't sealing right.
• Make sure it got winterized. If your irrigation company blew out your system in the fall but didn't drain the backflow preventer, mention it. The preventer needs to be drained or have its ball valves cracked open at a 45-degree angle to prevent freeze damage.

Don't Wait for the Deadline

Most people scramble to get their test done right before the town's deadline, and every backflow tester in the area is booked solid. Schedule it early in the spring when you do your sprinkler startup and you'll avoid the rush.

Trailhead Lawn & Irrigation offers backflow testing and repair across Erie, Longmont, Louisville, Lafayette, Frederick, Firestone, and Weld County. We can bundle it with your spring startup so you knock out both in one visit. Give us a call to get on the schedule.