See what happens during a certified backflow test

Backflow preventers stop contaminated water from being pulled or pushed back into the public drinking supply. A pressure drop in the main, or a sudden increase in downstream pressure, can siphon water backward and force it into the local drinking water.

Every retail water agency across the Peninsula and South Bay requires businesses to have their backflow preventers tested at least once a year. Our Certified Testers work directly with all of them every day.

A backflow test is a precision procedure, not a box to tick in a hurry. Caccia’s licensed professionals handle the paperwork and testing for you, then file the results on your behalf. Documentation has to be fully reviewed and updated during the call.

A lapsed test is a compliance concern. It can lead to trouble with the local water purveyor, because it tells them the assembly’s condition went unverified for an extended period. Flagging it on the call gave the customer the chance to correct it first.

Yearly tests are mandatory, not optional. They must be completed and filed on time by a certified tester using a calibrated gauge. If the unit fails and causes an issue, the business could be exposed to fines or even lawsuits.

Before a single reading is taken, the gauge and the assembly have to be prepped in a specific order.

Our technician started by confirming both bleed valves on the test gauge were fully closed, so nothing was open when the hoses went on. Leaving even one open would let water dump straight through the gauge and onto the ground.

Then, with a screwdriver, he opened the four test cocks on the backflow preventer in the sequence set by the American Water Works Association (AWWA): test cock 4, then 3, then 2, then 1.

He turned each one a quarter-turn, then closed them again in the opposite order. This flushes grit and water out of the ports and gets water moving through the assembly, so the relief valve is less likely to trip. Proper setup protects your equipment.

Next, the technician ran hoses from the Midwest Model 845 five-valve differential pressure test kit to the unit.

The gauge’s blue “low” hose went onto test cock 3 and the red “high” hose onto test cock 2. He then opened the bleed line on the gauge and let water flow through it and the assembly onto the ground. Flushing grit out of the lines and getting water moving again ensures an accurate result.

Once the needle floated back to the middle of the scale, he turned the water supply off completely. Putting the assembly at rest shows how well it holds pressure without any outside help. That is what we are looking for.

The Model 845 is a five-valve gauge, the best option for precise backflow testing. Opening or closing each valve one at a time gives a more accurate reading of the pressure inside the unit.

Always work with a certified tester.

Backflow preventers contain three separate valves that defend the line, and any one of them can fail without warning. You will not notice unless all three fail at once, so our certified testers always check each one individually.

With all four readings logged, the technician reversed the hookup in the same deliberate order: he shut the test cocks (high, then low, then the flow cock), vented the gauge, and pulled the hoses. Only then did he turn the customer’s water back on and cap every test cock.

The assembly passed. Our technician documented the test on site before leaving, then filed a copy with the appropriate authority on the customer’s behalf.

We also caught and resolved the missed compliance check on the customer’s fire suppression system on the same visit. We track the next due date for both in our system, so they never need to fall behind on either one again.