Backflow in plain language
Water is intended to move from the public supply into a property. Backflow is movement in the opposite direction. It can happen when supply pressure drops or when pressure inside a private system becomes higher than the public main.
A cross connection is a real or potential path between drinking water and another liquid or source. Irrigation, boilers, fire systems, process equipment and hoses can create different hazards. A backflow prevention assembly is installed to interrupt that reverse path.
What the field test measures
A visual inspection cannot prove how the internal checks or relief components perform under pressure. The tester connects calibrated differential-pressure equipment to the assembly’s test cocks and follows the procedure for that device type.
The exact readings differ for reduced-pressure assemblies, double-check assemblies and pressure-vacuum breakers. The report ties those readings to the manufacturer, model, serial number, size, location and property. That connection is why the device tag and correct address matter.
Why testing repeats every year
Backflow assemblies contain moving parts and resilient seals. Water conditions, debris, corrosion, temperature, use and age can change how they perform. A device that passed last year is not assumed to remain reliable forever.
Chilliwack’s public Cross Connection Control FAQ explains that moving parts are subject to fouling, wear and fatigue, and says devices are tested yearly or as directed. The Township of Langley similarly states that its assemblies need annual testing.
Why you received a notice
Municipal programs track registered assemblies and their due dates. The letter usually identifies the property account, assembly or deadline needed to match the field result to the City record. In Surrey, the Customer Account number on the owner’s notice is required for portal submissions tied to the property.
Do not discard the letter after booking. Send a clear image to the provider and keep the original with the completed report or submission confirmation.
What happens during and after the visit
The tester confirms the device, assesses access and condition, isolates it as required and performs the field procedure. Water interruption depends on how the system is installed. A passing result moves to the municipality’s reporting path.
If the assembly fails, the readings identify where performance did not meet the requirement. The owner then considers repair or replacement. After approved work, the device is retested; the repair alone does not establish a passing result.
How to respond to the letter
Confirm the due date and municipality, locate the device, find any previous report and identify who can provide access. Ask the provider to confirm its current eligibility for that City and how it handles the report and fee.
Finally, store the completed report, repair record and submission confirmation with the property file. The next annual cycle becomes much easier when the device details and access notes are already known.
Official sources
Municipal procedures change. Use these sources and the latest property notice as the final authority.
City of Chilliwack Cross Connection Control FAQTownship of Langley water quality reportCity of Surrey testing portal