Backflow Prevention for Fire Line Taps in Denver
An independent, licensed plumbing contractor. Not affiliated with Denver Water or the City and County of Denver.
Backflow prevention on a fire line tap installs and maintains an assembly that stops water in a fire suppression system from siphoning or being forced back into the municipal supply. Denver Sewer and Water installs these assemblies at the tap and arranges the certified testing that water authorities require to keep the connection in compliance.
- Reduced pressure zone and double check assemblies sized to the fire line's demand.
- Installation at or near the tap where the water authority requires it.
- Coordination with a certified backflow tester for initial and annual testing.
- Repair and replacement of failed or leaking backflow assemblies.
- Documentation prepared for the water authority's records.
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Why Does a Fire Line Need Its Own Backflow Assembly?
Water sitting inside a sprinkler or standpipe system for months at a time is not the same water flowing through a domestic tap. It can pick up sediment, metal from the pipe itself, or additives used in some suppression systems. A backflow assembly on the fire line tap is the barrier that keeps that water from ever reaching the drinking water main under a pressure drop or cross connection event.
Water authorities require these assemblies precisely because a fire line is a cross connection by design: it joins the potable water system to a separate piped system that is not held to drinking water standards. Testing them on a schedule confirms the check valves are still holding and have not been fouled or jammed.
(720) 935-6221Common backflow assembly issues on fire lines
- Check valves that no longer seat fully due to debris or corrosion.
- Relief valve discharge on a reduced pressure zone assembly indicating a failing check.
- An assembly sized for an older, lower fire flow demand.
- Missing or expired test documentation with the water authority.
- Freeze damage on an assembly housed in an unheated vault or enclosure.
- An assembly installed at the wrong location relative to the tap.
How We Diagnose It
How a Backflow Assembly Is Evaluated
A certified tester runs a differential pressure test on each check valve and the relief valve where present, confirming each component holds at the pressure it is rated for. Where an assembly fails, we determine whether it is a serviceable repair, such as replacing internal check seats, or whether the assembly itself needs replacement.
What the test confirms
- Each check valve holds its rated differential pressure.
- The relief valve on a reduced pressure zone assembly opens correctly.
- Shutoff valves on either side of the assembly fully isolate it.
- The assembly is accessible for testing as required.
How Backflow Work Is Handled on a Fire Line Tap
- 1
Confirm assembly type and sizing
We confirm whether a double check or reduced pressure zone assembly is required based on the fire line's hazard classification and demand.
- 2
Install at the correct location
The assembly is installed at the tap or at the point the water authority specifies, with proper support and freeze protection.
- 3
Arrange certified testing
A certified backflow tester performs the required test and files results with the applicable water authority.
- 4
Repair or replace as needed
Failed assemblies are repaired where the internals can be serviced, or replaced where the housing or body is no longer reliable.
What Denver Customers Say About Working With Us
“Denver Water And Sewer did an excellent job replacing my sewer lines. Trevor and his crew are extremely competent, honest, professional and prompt.”
“Denver Sewer and Water was a great experience. We had been out of water due to a water main leak into the house for 2 weeks. They came out, gave a go”
“We had an underground water valve break on a Saturday. No fun and expensive to fix regardless of the repair company. Nevertheless, greatly apprecia”
What Drives Backflow Assembly Cost on a Fire Line
Assembly size, driven by the fire line's flow demand, is the main factor, along with whether the installation is new or a replacement of an existing enclosure or vault. Accessibility matters too, since an assembly buried in a vault takes longer to service than one mounted above grade in a heated room.
Ongoing cost is mostly the recurring certified test, which is a small, predictable line item compared to what a lapsed test can cost a building if the fire line service is suspended for noncompliance.
Call (720) 935-6221 to have the existing assembly evaluated or a new one specified.
Frequently Asked Questions
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Call (720) 935-6221 to get it evaluated and tested.