Irrigation Blowout & Winterization
The autumn appointment where the assembly gets drained and covered.
Learn moreIrrigation
The Brass Assembly That Freezes First
A backflow preventer sits above ground, full of water, made of brass and small internal parts. It is the most exposed component on an irrigation system and the most expensive thing a missed blowout will break, usually discovered as a fountain on the first day of the season.
Lines are open right now:
(833) 472-2088
Water spraying from the assembly? Close the irrigation supply, then call.
Repair and replace
Rebuild kits where the body is sound, replacement where it is cracked.
No testing here
We do not perform certification testing. We will say who does.
Freeze casualty
Above ground, water-filled, brass. It is always first to fail.
Protects drinking water
The reason the device exists, and why it is not optional.
Purpose
A one-way door between your sprinklers and your drinking water
Backflow is what happens when water in a system reverses direction, pulled backwards by a pressure drop in the supply, or pushed backwards by pressure on the downstream side. Without protection, that reversal can draw water from a sprinkler line, a hose sitting in a bucket, or an irrigation system into the potable supply. Irrigation water in the Treasure Valley is surface water; a lawn has fertiliser and animal waste on it. Neither belongs in a kitchen tap.
A backflow prevention assembly is the mechanical answer: a set of check valves and, depending on the type, a relief mechanism that opens to atmosphere rather than allowing reverse flow. Once installed it does its job silently for years, and the only time most homeowners think about it is when it fails.
The types you will encounter on residential and light commercial property in Idaho are the pressure vacuum breaker, the double check valve assembly and the reduced pressure zone assembly, along with simpler atmospheric vacuum breakers and hose bib vacuum breakers on individual outlets. Which one is appropriate depends on the degree of hazard and on local requirements, which vary by city, district and water provider, that is not something to guess at, and it is a question your provider can answer directly.
What we do and do not do
The plumber repairs, rebuild and replaces backflow assemblies, and we deal with the plumbing either side of them. We do not perform backflow certification testing. Where testing is required, and for many properties in Idaho it is, annually, your water provider or irrigation district maintains a list of who performs it locally.
Cracked body or worn internals? We'll tell you which before quoting.
Failure modes
Four ways an assembly stops working
Freeze damage
The dominant cause in this state, and it is preventable. Water left in the body over winter expands and cracks the brass, splits the bonnet, or destroys internal poppets and springs. The failure is discovered at startup: water spraying from the body or from a split fitting the moment supply arrives. A cracked body is not repairable, the assembly gets replaced.
Debris and fouling
Grit, sand and scale hold a check valve off its seat. The symptom is continuous discharge from the relief port on a reduced pressure assembly, or water weeping from the vacuum breaker. Cleaning and a rebuild kit usually solve it, and it is far more common on surface-water irrigation supply than on treated municipal water.
Worn internals
Rubber seats, discs, springs and o-rings age. An assembly that has been in service ten or fifteen years will eventually fail a test on worn parts alone, with nothing dramatic to see. Rebuild kits exist for most common assemblies and are considerably cheaper than replacement.
Installation problems
Assemblies installed at the wrong height, oriented incorrectly, or fitted with the wrong type for the hazard. These pass unnoticed for years and then surface when a test is performed or a problem arises. Correcting them means re-plumbing rather than repairing.
The decision
Rebuild kit, or new assembly?
The deciding factor is the body. If the brass is sound and the fault is internal, worn seats, a fouled check, a failed spring, a rebuild is the right answer, and it restores the assembly to working condition at a fraction of replacement cost. Rebuild kits are available for most common residential assemblies, and the work is an hour or so.
Replacement is required when the body is cracked or split, which is what freeze damage usually produces. It also makes sense when the assembly is obsolete and parts are no longer readily available, when the wrong type was installed for the application, or when repeated repairs have accumulated to the point where the arithmetic favours new.
One consideration that is easy to miss: where an assembly is being replaced, it is worth taking the opportunity to correct the installation at the same time, height, orientation, isolation valves either side, drainage and freeze protection. Doing that during a replacement costs very little extra. Doing it later means a second visit and cutting into new pipe.
Where testing is required for your property, the sequence matters. A repaired or replaced assembly generally needs to be tested afterwards, and the tester is a separate provider. Getting the repair done early in the season rather than at the deadline gives room for that to happen without pressure.
Repairs done early in the season leave room for testing afterwards.
Prevention
Keeping the assembly alive through an Idaho winter
Nearly every backflow replacement we do in spring was avoidable in October. The protection routine is short.
Drain it. As part of the autumn blowout, the assembly body is emptied: supply isolated, test cocks opened to let water out and air in, and the downstream side cleared. Water that cannot be drained cannot be prevented from freezing.
Leave the valves partly open. Ball valves set at roughly forty-five degrees give any residual water somewhere to expand rather than splitting the valve body. It is a detail that costs nothing and prevents a common failure.
Insulate what stays outside. An insulated cover or a purpose-made pouch over the assembly, secured against wind. Loose fibreglass stuffed into a plastic bag is better than nothing but tends to absorb water and stop working. Where the assembly is in an exposed windy position, common on the Snake River Plain, this matters more.
Consider removal. Some assemblies can be unbolted and stored indoors for the winter, with the exposed pipe capped. Whether that is appropriate depends on the type and on local requirements, and it is worth asking rather than assuming.
All of this is normally done as part of the irrigation blowout, which is the appointment where the assembly gets the attention it needs.
Elsewhere on the property
The small backflow devices people forget
Irrigation assemblies get the attention because they are large, visible and expensive. There are smaller devices around most houses doing the same job, and they fail quietly.
Hose bib vacuum breakers. The small brass fitting screwed onto an outdoor tap, or built into a frost-free sillcock. It prevents water being drawn back through a hose, which matters because hoses end up in buckets, ponds, and connected to sprayers full of chemicals. They corrode, they seize, and on frost-free bibs a failed internal breaker can prevent the bib draining properly, which then causes a freeze split. See outdoor hose bib repair.
Boiler and heating system protection. Where a hydronic system is filled from potable supply, a backflow device separates the two. Heating water contains inhibitors and years of accumulated corrosion products.
Well and auxiliary supplies. Where a property has both a well and a municipal connection, cross-connection control is a serious matter and the rules are specific. Any arrangement where two water sources could meet needs to be looked at properly.
Irrigation on household supply. Outside the Treasure Valley, sprinklers usually run off the household supply rather than a separate delivery, which means the backflow device is protecting your own drinking water directly. It is no less important there, and often less well maintained because there is no district requirement prompting anyone to look at it.
Draining and covering it in autumn prevents nearly all of this.
How it runs
A backflow visit
Short work, provided the diagnosis is right about whether the body survived.
Isolate and inspect
Supply closed, assembly examined for cracks in the body, bonnet and fittings, and the type and size identified for parts.
Rebuild or replace
Internals cleaned or a rebuild kit fitted where the body is sound; full replacement with corrected installation where it is not. Priced before work starts.
Recharge and check
Supply restored slowly, the assembly watched under pressure, and you are told whether a certification test is needed and who performs it locally.
Coverage
Assemblies across the state
Backflow assemblies are most numerous in the Treasure Valley, where pressurized irrigation delivery makes them standard on residential property. Elsewhere they protect household supply from sprinkler systems, boilers and auxiliary water sources, less visible, and often overdue for attention.
Questions
Backflow questions
No. The plumber repairs, rebuild and replaces them, and we handle the plumbing on either side, but certification testing is a separate service. Requirements vary across Idaho by city, water provider and irrigation district, your provider maintains a list of who tests locally and how often yours is due.
Close the supply valve to the irrigation system, which stops the flow immediately, then call. Continuous discharge at startup is almost always freeze damage to the body or a check valve fouled open. Neither improves with waiting, and on a metered supply the water is being paid for the entire time.
If the damage is internal, springs, poppets, seats, then yes, with a rebuild kit, and that is a straightforward job. If the brass body, bonnet or a fitting has cracked, it gets replaced. Freeze damage tends to produce the second outcome, which is precisely why the autumn drain-down matters.
Because most types have to be. Pressure vacuum breakers and reduced pressure assemblies rely on venting to atmosphere and must be installed above the highest downstream outlet, at a specified height. Burying them would defeat the mechanism. Protection over winter is the trade-off for a device that works.
Some assemblies can be unbolted, stored indoors and reinstalled in spring, with the pipe capped in the meantime. Whether that is suitable depends on the type of assembly and any local requirements, and if the property is subject to annual testing there may be implications. Ask before doing it the first time.
Not on age alone. Rubber internals wear out over ten to fifteen years and a rebuild kit restores the assembly at modest cost, so a well-maintained older unit with a sound body has plenty of life. Replacement is warranted for cracked bodies, obsolete units with no parts available, and installations that were wrong to begin with.
It is a small device doing a real job. A hose left in a bucket, a pool, or attached to a chemical sprayer creates a direct path into your supply if pressure drops. They cost very little, they screw on in a minute, and on frost-free sillcocks a failed internal breaker can also stop the bib draining, which turns into a freeze split inside the wall.
Yes, and arguably it matters more, because the irrigation piping connects directly to the water you drink rather than to a separate surface-water system. Requirements vary by provider, but the underlying reason for the device does not change with geography.
Testing is someone else's job, we'll point you to them.
Drained in October, or replaced in April.
The assembly is the most exposed and most expensive part of an irrigation system. Protecting it takes ten minutes a year; replacing it does not.
(833) 472-2088