The backflow letter is real — here's what it's asking
A letter arrives from your water district about a “backflow prevention assembly” you may not know you own, demanding a test by a certified professional, with a deadline and a shutoff warning. It reads like a scam. It isn’t — and the fastest way to make it painless is to understand the three layers behind it.
Layer 1: the state rule your district can’t ignore
Colorado’s drinking water regulations — Regulation 11, section 11.39 (Backflow Prevention and Cross-Connection Control) — require every public water system in the state to run a program that finds cross-connections and makes sure backflow assemblies are tested. The rule was updated effective October 15, 2023, and CDPHE publishes the guidance, templates, and forms districts build their programs from (CDPHE BPCCC program page). Your district isn’t inventing this; the state requires it of them, and they pass the requirement to you.
The legislature touched it recently too: HB25-1077 (signed March 2025) added certified cross-connection control technicians to who may inspect, test, and repair these assemblies — CDPHE’s note is on the same page.
Layer 2: what a backflow assembly does
The assembly is a one-way gate between your plumbing and everyone’s drinking water. Sprinkler systems, fire lines, commercial equipment — anything that could siphon backwards under pressure loss — must be walled off from the public supply. Denver Water’s program states the scope plainly: all commercial, industrial, irrigation, and fire-line services need an approved assembly; homes are assessed by hazard; and any property with an auxiliary water source — a well or a pond — needs one too (Denver Water program page). On a well? Our sibling site Well Test Colorado covers that world.
Layer 3: the test the letter demands
The assembly must be tested when it’s installed and every year after that, by a certified backflow prevention assembly tester — that’s Denver Water’s stated requirement under Regulation 11, and the pattern repeats across districts. The tester runs the assembly through its paces, fills out your district’s report, and files it where your district requires (email for some, an online portal for others — see where to send your test).
What ignoring it costs
Districts enforce with the one lever they all have: the water itself. Denver Water’s program FAQ answers, in its own words, the question “My water was recently shutoff due to my backflow not being tested or installed. Why was I charged $250 on my water bill?” — the shutoff is real, and so is the reconnection charge. Deadlines and enforcement vary by district; the date on YOUR letter is the one that counts.
The short version
- The letter is state-mandated, not junk.
- The test is annual, by a certified tester — this year’s pass starts next year’s clock.
- Your district’s submission process is specific; a tester who works your district files it right the first time.
Use the form on this page, tell us your district, and we’ll connect you with a certified tester who handles the paperwork end of it too.