Backflow testing makes sure your backflow preventer is working properly by checking your water pressure levels to make sure contaminated water isn't getting into your water line. A broken or faulty backflow preventer can let wastewater get into clean drinking water and cause illnesses.

Backflow testing costs $30 to $300 per device, depending on your location and whether the test finds any problems. Backflow preventers require annual testing to make sure they’re working and that your water isn’t contaminated. Most backflow preventer systems in residential homes use one device. Commercial systems, on the other hand, use 2 to 3.

A new backflow preventer costs $200 to $1,000 with installation, depending on the valve type. Many cities require backflow preventers for commercial businesses and multi-family homes. You may also need one if you have a single-family home with an irrigation system, inground pool, or septic system.

Cities require backflow testing because the smallest malfunctions in a backflow detection system can be extremely dangerous. Drinking or bathing in unsanitary water can cause several different health issues, so it’s vital to evaluate your system every year.

You may also want to check your system if you notice any of the following issues, even before it's time for your annual test:

• Slow drainage
• Cloudy or discolored water
• Uneven water pressure

Backflow testing usually takes 20 to 30 minutes for smaller residential systems. Large commercial systems with two or more preventer devices take longer to test.

You can be confident you're picking a high-quality backflow testing company by following these steps:

• Contact multiple companies for estimates and compare costs.
• Look at reviews on HomeGuide and Google.
• Ask how much experience they have testing backflow preventers.
• Ask if they'll charge a flat rate or an hourly fee. Ask them about any other costs, such as service fees or material charges.

Ask the service providers these questions before hiring anyone:

• Are you licensed and insured?
• How long have you been testing backflow preventers?
• What is the total cost for the test? Does that include labor and city fees?
• Can you give me a few references from previous clients?
• How long will the test take?
• Will you handle any repairs if necessary?
• Will you write the report and deliver it to city officials yourself?
• Do you charge a flat fee or an hourly fee?
• What’s your policy for unexpected problems during the job?