If your commercial building in Denver has a fire sprinkler system, it also has a backflow preventer — and that device must be tested every year. Missing the deadline can mean fines or a water shutoff notice from Denver Water. It is one of the most commonly overlooked compliance items for property managers on the Front Range, and it is one of the easiest to get ahead of.
What Is a Backflow Preventer and Why Is It on Your Fire Line?
A backflow preventer (BFP) is a mechanical assembly installed where your fire sprinkler system connects to the public water supply. Its job is to stop water from flowing backward — from your building’s fire system back into Denver Water’s drinking water supply.
Fire sprinkler systems are considered a high-hazard cross-connection because the water sitting in your pipes may contain antifreeze, corrosion inhibitors, or other additives. Denver Water, like every water utility on the Front Range, requires an approved backflow prevention assembly on every fire line to protect the public water supply from contamination.
The two most common assemblies on commercial fire lines in Denver are:
- RPZ (Reduced Pressure Zone) — required when the fire system contains antifreeze or chemical additives, or when the hazard level is high (hospitals, labs, industrial). This is the most protective type and the most common on Front Range commercial systems.
- DC (Double Check) — used on fire lines without additives in lower-hazard applications.
Your assembly type matters because the testing procedure and pass/fail criteria differ between the two.
The Annual Testing Requirement
Denver Water’s Cross-Connection Control program requires that every backflow prevention assembly be tested upon installation and every year after that by a certified tester. The annual deadline for Denver Water customers is April 15th. Miss it and you risk fines or, in serious cases, a temporary water shutoff.
Test results must be submitted directly to Denver Water’s Cross-Connection Control office at [email protected]. Your contractor handles this submission — but it is worth confirming they did it.
Other Front Range utilities run similar programs on their own schedules:
- Aurora Water — annual testing required, submit results to Aurora’s Cross-Connection program
- Boulder PWD — annual testing required, managed through Boulder’s Backflow Prevention program
- Fort Collins Utilities — annual testing required
- City of Cheyenne BoPU — annual testing required
If your property is served by any of these utilities, the requirement is the same: annual testing, certified tester, results submitted to the utility.
What Changed in Colorado in 2025
Colorado’s HB25-1077, passed by the General Assembly in 2025, made an important clarification about who can legally test backflow assemblies. Under the new law, a certified backflow assembly tester — holding either an ABPA or ASSE certification — can test, inspect, and repair domestic and irrigation assemblies without a plumbing license.
Fire sprinkler assemblies are different. To test and repair the backflow preventer on a fire line in Colorado, the contractor must hold a Fire Suppression System Contractor — Backflow certification from the state, in addition to the standard backflow tester certification. Denver Water enforces this requirement.
This matters when you are getting quotes. Not every plumber or general backflow tester is qualified to work on your fire line assembly. If someone shows up without the fire suppression backflow certification, their test report will not be accepted by Denver Water.
What the Test Actually Involves
A backflow test on a fire line typically takes 15 to 30 minutes. The certified tester will:
- Notify you before shutting the water — your sprinkler system will be offline briefly during the test
- Attach differential pressure gauges to the test cocks on the assembly
- Verify that the check valves and relief valve (on an RPZ) are holding within acceptable pressure ranges
- Complete a test report form and submit it to the water utility
If the assembly fails — a check valve that is not seating properly, a relief valve that opens too early — it must be repaired and retested before the report can be submitted as passing. Repairs on fire line assemblies require the same Fire Suppression Contractor — Backflow certification as the test itself.
What to Do If You Have Not Tested This Year
If your annual backflow test is overdue, here is what to do:
- Find your assembly. It is typically in your mechanical room, near where the fire line enters the building, or in a vault outside. It looks like a brass or bronze fitting with test cocks and, on an RPZ, a relief port in the middle.
- Check your records. Look for a test report from last year. If you cannot find one, assume it has not been done.
- Schedule the test now. Do not wait until April — contractors get backed up as the deadline approaches. Summer and early fall are the best times to schedule.
- Confirm the contractor is certified. Ask specifically for their Colorado Fire Suppression System Contractor — Backflow certification before scheduling.
What This Means for Your Building
Backflow testing is not optional and the consequences for skipping it are real — fines, failed insurance inspections, and potential water service interruption. The good news is that it is a quick, inexpensive test when the assembly is in good shape. Staying current means one less item on your compliance checklist and no surprises at renewal time.
Elevation Fire Protection is certified to test, repair, and report backflow assemblies on fire sprinkler systems throughout Denver, Aurora, Boulder, Fort Collins, and Cheyenne. If you are not sure when your last test was done or whether your assembly is due, we are happy to check. Visit our backflow testing page or call us at (720) 382-9669.