What Is Backflow Testing?

Backflow testing is the annual inspection and pressure test of a backflow prevention assembly — a mechanical device that protects the public water supply from contamination caused by reversed water flow. If your property has an irrigation system, fire sprinkler line, or commercial water connection in Indiana, you almost certainly have one of these devices installed, and annual testing is likely required by your water utility.

What Is Backflow?

Backflow occurs when water flows backward through a plumbing connection — from your property’s piping into the public water distribution system. This reverse flow can carry dangerous contaminants including fertilizers, pesticides, cleaning chemicals, human waste, industrial fluids, and even sewage directly into the drinking water supply.

There are two main conditions that cause backflow:

• Back-pressure backflow — when the pressure in your downstream piping exceeds the supply pressure. This commonly happens in systems with booster pumps, heat exchangers, or elevated storage tanks.
• Back-siphonage backflow — when a sudden drop in supply pressure (such as during a water main break or fire department pumping operation) creates a vacuum that pulls water backward from your system into the main.

Both scenarios are real events that occur regularly across Indiana. A functioning backflow prevention assembly is the primary mechanical barrier preventing contaminated water from entering the public supply.

What Is a Backflow Prevention Assembly?

A backflow prevention assembly (BPA) is a mechanical valve device installed at the point where your plumbing connects to the municipal water system (the “service connection”). These devices contain springs, rubber seals, check valves, and diaphragms that wear down over time. Annual testing confirms all components are still functioning within safe pressure tolerances.

The four main types of assemblies used in Indiana are:

• Reduced Pressure Zone (RPZ) Assembly — the gold standard for high-hazard connections. Uses two check valves and an automatic relief valve. Required for fire lines, irrigation systems with chemical injection, and most commercial and industrial connections.
• Double Check Valve Assembly (DCVA) — two independently acting check valves in series. Used for low-to-moderate hazard connections including basic irrigation systems and apartment building water services.
• Pressure Vacuum Breaker (PVB) — a spring-loaded check valve with an air inlet. Commonly used on residential and commercial irrigation systems. Must be installed above the highest outlet on the irrigated system.
• Atmospheric Vacuum Breaker (AVB) — the simplest device, used for individual hose bibs. Not testable under pressure — typically does not require annual field testing, but must be inspected for proper operation.

Why Is Annual Testing Required?

Backflow prevention devices are mechanical systems with moving parts. Rubber seals dry out and crack. Springs lose tension. Debris from the water supply collects on check valve seats and prevents them from sealing completely. A device that passed last year’s test may be non-functional today.

Indiana water utilities require annual testing under their cross-connection control programs, which are governed by IDEM (Indiana Department of Environmental Management). IDEM adopted the American Water Works Association (AWWA) standards as the baseline for cross-connection control in Indiana, requiring utilities to maintain active programs that include annual testing requirements for qualifying assemblies.

Annual testing serves three purposes:

1. Verify the device is working — a passing test confirms all valves open and close correctly and hold within allowable pressure differentials.
2. Identify failures before contamination occurs — a failing assembly can be repaired before a backflow event happens, rather than after.
3. Maintain regulatory compliance — test reports submitted to your utility document your compliance and protect you from fines or service interruption.

What Does the Testing Process Involve?

A certified backflow tester uses a calibrated differential pressure gauge (a “test kit”) to measure the pressure differential across each check valve and relief valve in the assembly. The test typically takes 15 to 45 minutes depending on the device type and accessibility.

Here is what happens during a standard test:

1. The tester attaches their test kit to the test cocks on the assembly.
2. They isolate the downstream shutoff valve and measure pressure across check valve #1.
3. For RPZ assemblies, they measure the differential pressure across the relief valve to confirm it opens at the correct threshold.
4. They check valve #2 by isolating it and measuring the pressure differential.
5. They record all measured values on a standardized test report form.
6. If the assembly passes, they complete the report with a passing designation and submit it to your utility. If it fails, they note the specific component failure and recommend repair.

Water service is typically shut off during the test — usually for only a few minutes. Most residential and small commercial tests cause minimal interruption.

Who Performs Backflow Testing?

Testing must be performed by a state-certified backflow tester. In Indiana, testers typically hold one of the following credentials:

• ASSE 5110 — Backflow Prevention Assembly Tester (most common)
• ASSE 5120 — Backflow Prevention Assembly Repair Technician (can also test)
• Utility-specific certifications accepted by your local water utility

Many Indiana water utilities maintain their own approved tester lists. Before hiring a tester, confirm with your utility that the tester is on their approved list — otherwise your test report may not be accepted. This directory lists state-certified testers and notes their credentials and service areas to help you find a pre-approved tester quickly.

What Happens If Your Assembly Fails the Test?

A failed test does not mean your water service is immediately shut off — but it does require prompt action. Here’s the typical process:

1. Your tester documents the failure on their report and explains which component failed.
2. You hire a licensed plumber to repair or replace the assembly. In Indiana, assembly repair must be performed by a licensed plumber (not just a tester), though some certified testers are also licensed plumbers.
3. After repair, a certified tester performs a new test on the repaired/replaced device.
4. The passing re-test report is submitted to your utility within the required timeframe.

If you receive a failure notice and do not take action, your utility may issue a notice of non-compliance and, ultimately, interrupt water service to your property.

How to Find a Certified Tester in Indiana

Use the Indiana Backflow Testing Directory to search for certified testers by city, county, or service type. Each listing includes the tester’s certification type, service areas, contact information, and in many cases direct quote request capability. Always verify that your chosen tester is on your utility’s approved list before scheduling service.