Most Kamloops homeowners don't think about backflow — until there's a problem. Backflow occurs when water flows in the wrong direction through your plumbing, potentially pulling contaminants from irrigation systems, garden hoses, or appliances back into your clean drinking water supply. It's a real risk, and BC building code requires backflow prevention devices in a number of situations. Here's what you need to know.

What Causes Backflow?

Your water supply relies on consistent pressure to move water from the municipal main into your home. When that pressure drops — due to a water main break, heavy demand on the city system, or firefighting activity in your neighbourhood — water can actually reverse direction and flow back toward the supply. If a hose is submerged in a bucket of soapy water, or a sprinkler head is sitting in a puddle, that contaminated water can get pulled into the supply line.

This isn't a theoretical risk. Health authorities across BC have recorded cases of household chemical contamination traced to backflow events. In Kamloops, the combination of an active irrigation season and summer peak demand on the municipal system creates real conditions for backflow to occur.

Types of Backflow Prevention Devices

Air Gaps

The simplest and most reliable form of backflow prevention is a physical air gap — a space between a water outlet and the flood level of a fixture. The gap in your kitchen sink faucet is a common example. Air gaps require no maintenance and cannot fail mechanically, but they're not practical for every application.

Hose Bib Vacuum Breakers

These small, inexpensive devices attach directly to outdoor hose bibs and are required by BC plumbing code on all residential outdoor taps. If you don't have them on your outdoor faucets, this is an easy and affordable fix. They prevent water from being siphoned back through a connected hose.

Pressure Vacuum Breakers (PVB)

Commonly installed on irrigation systems, PVBs open to atmosphere when pressure drops, breaking the siphon before backflow can occur. BC code requires a backflow preventer on any irrigation system connected to a potable water supply. If your in-ground sprinkler system was installed without one — or if it's never been tested — this is worth addressing before irrigation season gets underway.

Reduced Pressure Zone (RPZ) Assemblies

RPZ assemblies provide the highest level of protection and are required for higher-hazard connections — commercial properties, homes with chemical injection systems, or connections to non-potable water sources. They include a testable relief valve and must be inspected and tested annually by a certified tester.

Do You Need a Backflow Preventer?

In most cases, yes — and you may already be required to have one under BC plumbing code. Situations that typically require a backflow prevention device include:

• Any in-ground irrigation or sprinkler system connected to the home's water supply
• Outdoor hose bibs (vacuum breakers required on all exterior taps)
• Boilers and hydronic heating systems connected to potable supply
• Homes with a swimming pool or hot tub with a fill connection
• Any appliance where the supply inlet could be submerged (some dishwashers, washing machines)

Annual Testing Requirements

Testable backflow prevention assemblies — PVBs, double check valves, and RPZ assemblies — must be tested annually in BC by a certified backflow tester. Many homeowners with irrigation systems aren't aware of this requirement. If your device has never been tested, or you're not sure whether one was installed when your irrigation system was put in, it's worth having a plumber take a look before you open the system up for the season.

Advanced Plumbing Kamloops installs, services, and tests backflow prevention devices throughout Kamloops and the Thompson-Nicola region. If you have questions about your home's setup — or want to make sure you're meeting code requirements before irrigation season — give us a call and we'll sort it out.