Backflow preventer repair and replacement cost
Backflow preventer replacement cost averages $350 in 2026, with most homeowners paying $150 to $450, per Angi. HomeGuide puts a new device at $200 to $1,000 installed, depending on type and size.
| Installation (Angi, avg $350) | $150–$450 |
| Larger devices / high-cost areas (Angi) | up to $1,100 |
| New device installed (HomeGuide) | $200–$1,000 |
| Sprinkler or sewer device, part only (HomeGuide) | $100–$600 |
| Freeze relief valve or anti-theft add-on (HomeGuide) | $100–$300 |
| Permit (Angi) | from $50 |
| Annual backflow test (HomeGuide, avg $165) | $30–$300 |
Where backflow preventers are used
Backflow preventers stop contaminated water from flowing back into the drinking water supply. Homes most often have them on irrigation systems, on fire sprinkler lines, on boiler feeds, or on sewer lines to stop sewage backing into a basement. Many water utilities require testable devices on these lines to be tested periodically; ask your utility what applies to you.
Repair or replace?
A device that fails its test can often be rebuilt with new seals, springs or check valves. Replacement makes sense when the body is cracked, often from freezing, or when parts are no longer available. Ask the tester what failed and get a price for both options.
Protect it from freezing
Above-ground irrigation backflow devices are vulnerable in cold climates. Draining the system before winter, insulated covers or a freeze relief valve (HomeGuide: $100 to $300) prevent a cracked body.
Sewer backflow valves
A backwater valve on the main sewer line keeps municipal sewage from backing up into low drains during heavy storms. Angi's national average for a sewer backflow preventer installation is about $350. Pairing it with a sewer cleanout makes maintenance easier. If a backup has already happened: sewer backup steps.
Closed systems and water heaters
Adding a backflow preventer can close your plumbing system, which typically means an expansion tank is required for the water heater.
Frequently asked questions
How much does it cost to replace a backflow preventer?
Angi's 2026 average is $350 (most pay $150 to $450); HomeGuide lists $200 to $1,000 per device installed.
How much does backflow testing cost?
HomeGuide puts backflow testing at $30 to $300 per device, averaging $165.
Can a backflow preventer be repaired?
Often, by replacing internal seals, springs or checks. A cracked body usually means replacement.
Do I need a permit to install a backflow preventer?
Usually; Angi notes local permit fees start at $50.
Related cost guides
- Sewer cleanout installation cost
- Expansion tank installation cost
- Outdoor faucet replacement cost
- Water damage restoration cost
Sources
- Angi: backflow preventer installation cost (2026 data)
- HomeGuide: backflow preventer cost (2026)
- HomeGuide: backflow testing cost (2026)
National figures from published 2026 cost guides, retrieved 10 Oct 2026. Local prices, especially in high-cost metros, can be higher. Always get written quotes.