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Backflow Preventers
Water Is Supposed to Flow One Way. Sometimes It Does Not.
Your plumbing is designed so water moves from the utility main into the house and out through fixtures. But pressure in the main is not constant. A fire hydrant opens down the street, a main breaks, a pump kicks on, and for a moment the pressure in the street drops below the pressure in your yard. When that happens, water can be pulled backward, and what comes with it is whatever it was touching: fertilizer and pesticide from the sprinkler heads, pool chemicals, a hose left in a bucket of soap, or water from a boiler. A backflow preventer is a set of check valves and vents that closes that door automatically, protecting your family’s water and the neighborhood’s.
That is why most water utilities in Texas require a backflow prevention assembly on an irrigation system, and many require periodic testing by a licensed tester with a report on file. Radiant installs the correct type of assembly for the hazard, tests it with a calibrated gauge, repairs the checks and relief valves when they foul, and replaces assemblies that a hard freeze like February 2021 split open. For the specific device most sprinkler systems use, see our pressure vacuum breaker page. We also protect assemblies against winter on our frozen pipe visits, and check them as part of a whole-home plumbing inspection. New service lines to pools, outdoor kitchens and detached buildings get backflow protection sized in from the start; see water line services.
- Tested with a gauge, not a glance Each check valve and relief valve measured against its required differential and documented.
- The right assembly for the hazard PVB, double check or reduced pressure assembly, chosen by what is downstream and what the utility requires.
- Paperwork handled Test results recorded on the form your water utility uses, so the compliance letter stops coming.
What to Watch For
Signs Your Backflow Assembly Needs Attention
Most of these show up at the assembly itself, usually near the meter or where the irrigation line branches off.
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A test notice from the water utility
Utilities track assemblies and send reminders when a test is due. Ignoring it can lead to fines or a shutoff of the irrigation service.
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Water dripping or spraying from the assembly
A relief valve or air inlet discharging on and off is often normal; a steady stream means a fouled check that needs a rebuild.
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Cracks after a freeze
Assemblies sit above ground full of water. A hard freeze splits the brass body or bonnet, and the leak appears when the system runs in spring.
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Weak sprinkler pressure
A check valve stuck partly closed or debris caught in the seat robs the irrigation system of flow.
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A new sprinkler system, pool or outdoor kitchen
Any new connection that can hold contaminated water needs the right protection installed and, usually, an initial test.
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Corroded test cocks or a seized shutoff
If the ball valves on either side will not turn, the assembly cannot be isolated for testing or repair, and needs work first.
What We Do
Backflow Assemblies, Start to Finish
Install, test, rebuild, replace and protect, for every assembly type found on Central Texas homes.
- New assembly installation The correct device for the hazard, at the correct height and location, with isolation valves and test cocks that make future testing easy.
- Annual and initial testing Differential pressure testing of every check and relief valve with a calibrated gauge, and the results documented for your utility.
- Rebuilds and repairs Fouled checks, worn springs, failed relief valves and air inlets rebuilt with manufacturer kits when the body is sound.
- Replacement Freeze-split, corroded or obsolete assemblies replaced, and upgraded to the type the utility now requires where standards have changed.
- Freeze protection Insulated enclosures, proper draining before a front, and advice on shutting the irrigation supply when the forecast turns.
- Hose bib and fixture vacuum breakers The small devices on hose bibs, hand-held shower heads and utility sinks that keep a hose in a bucket from becoming a problem.
How It Works
How a Backflow Test Goes
A test does not take long. A repair, if it needs one, can often be done on the same visit.
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Locate and isolate
We find the assembly, confirm the type and serial, and close the downstream shutoff so the irrigation system is briefly off.
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Test each component
A calibrated gauge on the test cocks measures each check valve and, on a reduced pressure assembly, the relief valve, against the required values.
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Pass, or a priced repair
If it passes, the report is completed. If not, you get a written price for a rebuild or replacement and we can do it right then.
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Retest and document
Any repaired assembly is retested to confirm it passes, the results recorded, and the irrigation system turned back on.
Current Specials
Save on the work your home needs most.
Got a Backflow Test Notice?
We test, repair if needed, and complete the report. One visit, priced upfront.
What Our Customers Say
Don't just take our word for it — hear from our satisfied customers
★★★★★
I had Radiant Plumbing replace my tankless water heater, damaged in the Feb. 2021 snowmageddon storm with a new unit. The process was smooth and professional from start to finish. The plumber, James, was extremely knowledgeable and thoroughly explained my options to me. The cost and time to perform the installation were just as estimated. When he was done, James explained how to maintain the system, what service would be needed and how to perform it, and answered all of my engineering geek questions. It was a thoroughly positive experience. I have used several different plumbers in Austin over the past 15 yrs, but my search is over - I will not hesitate to call Radiant next time and would recommend them unreservedly.
8/9/23 Update: I have subsequently used Radiant for a toilet repair, faucet installation (Danny), and drain work (Ezekiel) and they have continued to impress with knowledgeable, friendly plumbers and quality work.
8/9/23 Update: I have subsequently used Radiant for a toilet repair, faucet installation (Danny), and drain work (Ezekiel) and they have continued to impress with knowledgeable, friendly plumbers and quality work.
★★★★★
We called Radiant Plumbing after we noticed a water leak in our kitchen. We were in a time crunch and they were able to schedule us quickly, before we left for vacation. They sent their representative, Preston Nichols, and he was excellent to deal with! He was on time, skillful, friendly, and very professional. It turned out to be a problem with our dishwasher but Preston was quick to diagnose it and set our minds at ease. While he was here, we mentioned that our one year-old water heater needed to be flushed. Preston was quick to take care of that, as well, saving us time and money in the process. Radiant charged us almost half the price another plumber quoted us for that service! While Radiant Plumbing isn’t our usual plumber, they gained a new customer. We won’t hesitate to call Radiant again in the future based on our VERY positive experience with them.
★★★★★
Had 3 different systems installed by them approx. 3 years ago for a total of approx $20k. I was quite happy with the install until the year later when they came for a maintenance call and started finding deficiencies in their own install. they wanted extra money to address those deficiencies. Now I am in the process of selling my home and an inspector has found a few items that need to be addressed and they will not even look at the report unless I schedule a $139.00 service call. Very poor customer service.. This company does not stand by their work and would not recommend.
I am revising my review of this business from 1 to 5 stars. After my original review I was contacted by the company's service manager and he made sure that I was taken care off. I had a team of 3 technicians coming to my house to double check the system and make the necessary adjustments. I was very satisfied by their attention to details and professionalism.
I am revising my review of this business from 1 to 5 stars. After my original review I was contacted by the company's service manager and he made sure that I was taken care off. I had a team of 3 technicians coming to my house to double check the system and make the necessary adjustments. I was very satisfied by their attention to details and professionalism.
Maintenance Membership
Join the Care Club
Home maintenance for $9.99 a month.
Care Club members get two HVAC tune-ups and a plumbing safety inspection every year, priority scheduling, no dispatch fees — ever — and 5% off every repair.
- Priority scheduling
- Seasonal HVAC tune-ups
- Annual safety inspection
- Exclusive member discounts
- Free dispatch on repairs
- No long-term contracts
Backflow Prevention Questions
What is backflow, and why does my water utility care about it?
Backflow is water moving the wrong way through your plumbing, from your property back toward the public main. It happens two ways. Backsiphonage is when pressure in the main drops suddenly, from a broken main or a hydrant being opened, and water gets pulled backward out of your pipes. Backpressure is when something on your side, like a pump or a boiler, pushes at higher pressure than the main. Either way, water that has been sitting in sprinkler lines with fertilizer, in a pool, or in a hose in a bucket can end up in the drinking water, not just yours but your neighbors’. That is why utilities require assemblies on connections with a contamination risk and track that they are tested and working.
Do I need a backflow preventer on my sprinkler system?
Almost certainly, yes. Irrigation is the most common backflow hazard on a residential lot, because sprinkler heads sit in soil that has been fertilized and treated, and a pressure drop in the main can pull that water back through the heads and into the supply. Most water utilities in Texas require an approved backflow prevention assembly on any irrigation connection, and most require it to be tested when installed and periodically after that by a licensed tester. If your system was installed by a licensed irrigator, it should already have one, usually a pressure vacuum breaker near the meter. If you are not sure your system has one, or that it has been tested, we can check it on a service visit and get you current.
How often does a backflow assembly have to be tested?
Your water utility sets the schedule, and annual testing is the most common requirement for residential irrigation assemblies. Some utilities require a test only at installation for lower-hazard connections and yearly for higher-hazard ones, and the rules differ between Austin, San Antonio and the smaller cities and water supply corporations around them. The utility typically sends a notice when a test is due, with a deadline and the form they want submitted. Whatever your utility requires, we test to it, record the results and give you what you need to file. Testing also catches problems early: a check valve that is starting to foul is a cheap rebuild now and a replacement later.
Why is my backflow preventer leaking water?
It depends on where the water is coming from and whether it stops. A reduced pressure assembly has a relief valve underneath that is designed to discharge briefly when supply pressure fluctuates; a spurt now and then is it doing its job. A pressure vacuum breaker vents a little from the top when the system shuts off and air enters. What is not normal is a steady stream or a continuous drip, which usually means a check valve is held open by debris, a spring has weakened or a seat is worn, and the assembly needs a rebuild. Water from a crack in the body, bonnet or a fitting, especially after a freeze, means the assembly is split and needs replacing. Either way, it is failing a test right now, so have it looked at.
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