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Valve boxes
Most backflow assemblies are installed in what we call a valve box. These are usually rectangular, plastic enclosures roughly 12" by 18", with green lids roughly flush with the ground. Their purpose is to enclose and protect below-ground plumbing system components, including your backflow assembly. Here are a few common examples:
A typical valve box. The backflow assembly inside serves a domestic line and has no upstream shutoff except the meter.
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This is a very common arrangement, especially for newer irrigation installations: backflow box in a rectangular valve box, with upstream isolation valve housed in a separate round box.
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It's hard to gauge size from the photo, but this is a larger ("jumbo") box, which is often used to contain a backflow assembly plus the upstream isolation valve.
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Locating your Backflow box
Water district reminder letters usually provide a serial number and location for your backflow assembly, to help you (and us) find and identify your equipment. You can also find this information on any prior test report. Some common locations are landscape strips between the sidewalk and curb (usually near the water meter), front corners of the yard (near, or across the sidewalk from, the water meter), front corner of the structure, or along the side of the structure. "Left" or "right" in location descriptions is usually intended to be interpreted as you stand at the curb and face the home.
Backflow box (yellow star) across the sidewalk from the water meter (blue raindrop).
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Backflow boxes (yellow stars) in the landscape strip next to water meters (blue raindrops) - the property line runs between the meters.
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Backflow box (yellow star) along the side of a home. The other box contains zone control valves and is downstream of the backflow and thus usually (but not always) further from the water meter.
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What's inside your backflow box
(Common 3/4" and 1" backflow models)
Below are examples of typical residential backflow assemblies (models noted below each photo). These below-grade installations all have four test ports and two shutoff handles in common. If you don't see handles, they're probably either buried or completely rusted away. For our work, we need to operate the handles AND the test ports, so please ensure these all are exposed and operational - if handles are missing, the assembly should be replaced before service.
Apollo DC4A
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Febco 850
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Wilkins 350
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Watts 775QT
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Wilkins 950XLT
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Watts 007M1QT
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If you don't see your assembly pictured above, you can click here to view types of assemblies that we don't see as often.
Upstream shutoff examples
Upstream shutoff valves are an important part of a well-designed irrigation system. They can be used to turn water on or off to your system for winterization or repairs. Because we frequently operate these during testing (especially when working on winterized systems), we thought we'd include some examples of what these look like in the wild. We may need to operate these for your work, so please make sure they're readily visible, accessible, and operable. (Note: these may be confused with drain valves, so please review the explanatory note at the bottom of this section).
PVC quarter-turn ball valve in dedicated round valve box
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PVC quarter-turn ball valve in backflow box (just upstream of backflow assembly)
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Gate valve in dedicated round valve box, wheel handle style
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Gate valve in backflow box, wheel handle style (just upstream of backflow assembly)
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Gate valve in backflow box, cross handle style (just upstream of backflow assembly)
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Gate valve in dedicated round valve box, cross handle style.
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Important note: these types of valves may also be used to open and close what are known as "drain valves." Drain valves are simply a length of pipe that ends at open air, with a shutoff valve at the end that can be opened and closed to allow water to drain from an irrigation system as part of the winterization process. When properly installed, drain valves should be downstream of your backflow assembly. If your shutoff valve is attached to piping that's open at one end, you're probably looking at a drain valve, not an upstream shutoff valve.
hidden valve boxes
We depend on being able to readily locate and access your valve boxes. We know it's tempting to hide them, but layers of bark dust, rocks, plants, or other materials hiding the box can unfortunately cause substantial delays for our technicians, who are working hard to serve you and other customers in a timely fashion. For this reason, we kindly ask that the valve box containing your backflow assembly is 100% visible and accessible before orders are placed. If water is off upstream (often the case for winterized irrigation systems), this also includes the box housing the upstream isolation valve. Here are some before and after examples of valve boxes we've uncovered:
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Side note: leaving soil, rocks, bark dust, or other landscape materials piled around the edge of the valve box, as shown here, can lead to debris tumbling into the box as we open it or kneel next to it for our work. To avoid this, make sure the surrounding area is level with the box lip.
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equipment often mistaken for backflow assemblies
The following boxes and pieces of equipment are NOT your backflow assembly or upstream shutoffs. We do not need access to this equipment - we've included these photos to help you identify these items if you come across them.
Plumbing and irrigation components
Note: these are NOT backflow assemblies, and we DO NOT need access to this equipment.
Water meter
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Pressure reducer (side view)
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Pressure reducer (top view)
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Zone control valves
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More zone control valves
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Filter and zone control valve
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AVB (an untestable and freeze-prone form of backflow prevention)
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Another AVB (these cannot be tested)
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Terminally cute baby snek
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Electrical and communications equipment
Note: These are NOT backflow assemblies, and we DO NOT need access to this equipment. Electrical and communication enclosures are often bolted or locked shut for safety and security. They're also likely to have markings on them with name of the power or telecom company (PGE, Pacificorp, Channell, Verizon, Comcast, etc.) or type of equipment inside.
Telecom box (company name shown on lid)
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Electric box
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Telecom pedestal
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Electrical transformer
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Electrical transformer
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Telecom pedestal
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Electrical pedestal
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Telecom pedestal
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Telecom pedestal
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How to open a valve box
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Getting those valve boxes open can be tricky! We use a medium-sized slot screwdriver, like the one shown here, to help open valve boxes.
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Box style: lid enclosed by box frame
This style of valve box lid rests entirely within the box frame. The screwdriver in the photo is positioned between the lid (green) and the box frame around it (black). The underside of this type of lid is equipped with a plastic latch that keeps the lid shut (next photo).
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Here's a view of the underside of the lid. The latch (black) secures the lid shut and is actuated via the hole on the top of the box. Very often, this latch breaks or is removed, so it may or may not be present.
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Side view: to open this style of box, begin by placing your slot screwdriver at a 90 degree angle into the hole in the box lid. It helps if the blade of the screwdriver is parallel with the short side of the box. If the latch is still present (or mostly intact), the screwdriver will stop a couple inches down as it makes contact with the latch.
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Next: while keeping firm pressure downward, tilt the screwdriver toward the nearest edge of the box frame. This pulls the latch free so the box can be opened.
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While keeping constant downward pressure on the screwdriver to keep the latch open, use your other hand to pull the screwdriver upward.
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If the latch is working properly and the lid isn't too jammed in, the lid should now open.
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Alternative method: if the latch is broken or the lid sticking, you can pry the lid open as pictured below. The top edge of the box frame is prone to cracking this way, but it's often the only effective method for removing the lid. The corner areas are stronger, but you won't get much useful leverage there. We're not fond of this style of box - the latches are finicky and fragile, and the lids have a tendency to stick, so we often have to resort to prying the lid open as shown below.
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Start by placing the screwdriver blade straight down between the box frame and lid.
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Then, lever the screwdriver down toward the ground. If the latch is holding the box shut, it helps to do this *as* you actuate the latch with a second screwdriver.
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You can place your finger in the hole and give the lid a tug for a last bit of extra oomph. Careful - the edges of this hole can be a little sharp, so you may want to wear gloves.
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Box style: lid overlaps box frame
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This style of lid comes in a few designs, but the one thing they have in common is that the lid (green) has a lip around the edge that partially or completely overlaps the box frame (black). These will often have "lift here" marked along one of the short edges of the box (pictured). In many cases, you can easily lift these right up with your finger. If not, they're pretty easy to open with a screwdriver, as shown below.
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Begin by placing your screwdriver between the lid and the box frame just below it (on the "lift here" side, if indicated) - angle your screwdriver as close to the ground as you can without grazing your knuckles.
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Next, simply tilt your screwdriver up to lever the lid open. The lid will usually pop right up.
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You should now be able to grip the lip of the lid and lift it open.
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Operability Challenges
When equipment has been poorly installed or maintained, this can present some serious testing challenges. Here are some examples.
Buried Equipment: the following boxes need dig-outs before the assemblies can be tested. Code requires 12" clear space below this equipment, though 4-8" is usually sufficient for testing purposes. Please make sure boxes are ready before your order.
Shutoff valves completely covered, and three (of four) test ports barely peeking above the soil.
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2-3 test ports just visible (will need a digout), and no visible shutoff valves. Extra piping crammed into box crowds test ports and will impede testing.
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Body of assembly half buried. Rocks and mud prevent operation of shutoff valves and at least one test port.
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Tight clearances, and other obstructions in the box: these assemblies below are installed with restrictive clearances. If anything is crowding the test ports or handles on your assembly, we may not be able to complete your test.
Shutoff valves too crowded to be operated with a handle wrench or adjustable wrench, one of which is often required to fully close the shutoff valves for testing.
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Piping over shutoff valves (hidden) and blocking access to test port operation points. Please allow 4" around all sides of the test ports, and 3" around shutoff valves.
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Test ports facing the side of the box, with limited clearances for attaching gauge and test adapters. Clearances less than 4" may prevent us from testing or require that we install elbow adapters.
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🌿VegEtation complications🌿
Because we love your plants and would rather not squish, trim, or otherwise alter them, we want you to know that we need a clear path to the box, two feet around all sides of the valve box and four feet directly above this work zone to allow space for our equipment, a spot to kneel in front of the box, room to move around the it, and a clear view of the work area. If this isn't done in advance as requested, plants in this work zone may be affected as we go about our work. If overgrowth is severe, or a repeat issue, we may need to put a hold on testing until we know that vegetation is cleared back for access and visibility.
🚫 Below are a few examples of plants that need trimming before testing. Fingers indicate valve boxes with backflow assemblies and as you can see, some are completely hidden! These are some more extreme examples, but even a little bit of vegetation in the face can really interfere with our ability to see and access your equipment.
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✅ And here are examples of good clearances between plants and valve boxes:
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Is water on to my backflow assembly?
We need to be able to get water to your backflow assembly for our work. Much of the time, especially during later winter and early spring, we test many backflow assemblies that serve winterized irrigation systems. As long as the shutoff valves (on the backflow assembly and upstream) are visible, accessible, and in good working order, a winterized system isn't usually an obstacle to our work. For most systems, we're interacting with three shutoff valves: the two on your backflow assembly, and one upstream (see our upstream shutoffs gallery above for examples). Shutoff valves fall into two main categories: quarter-turn ball valves, and gate valves.
Quarter-turn ball valves
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This is a very common set-up for an irrigation system: upstream shutoff valve, backflow assembly, and downstream drain valve, all enclosed in a single large box. All three of the labeled shutoff valves use a quarter-turn ball valve design, meaning a quarter turn will move the valve from the ON to the OFF position (or vice versa). Direction does matter, as these valves are usually designed with "stops" at each position: if the valve is on, a quarter turn clockwise will turn it off. From that position, a quarter turn counter-clockwise will turn it on. Quarter-turn handles parallel to the piping (or direction of flow) are in the ON position, and handles perpendicular to the piping (or direction of flow), are in the OFF position.
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For testing, we need to get water pressure to the test ports - depending on where water is turned off, we may need to operate all three of the shutoff valves in order to test and prevent downstream irrigation components (like your sprinkler heads, drain valves, etc.) from being pressurized. For this reason, it's important that we be able to readily locate, access, and operate all three of these valves when we visit. Upstream shutoff valves may be in a separate (often round) box just upstream of the backflow assembly, but they may be further away as well.
This quarter-turn ball valve on the backflow assembly is in the ON position, with the handle parallel to the piping.
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This quarter-turn ball valve on the backflow assembly is in the OFF position, with the handle perpendicular to the piping.
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This quarter-turn upstream shutoff valve is in the ON position, with the handle parallel to the piping.
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This quarter-turn upstream shutoff valve is in the OFF position, with the handle perpendicular to the piping.
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Gate valves
Gate valves require quite a bit of turning to fully open and close. Unfortunately, there's no way to visually determine the position of these valves. Turning clockwise closes the valve, and turning counter-clockwise opens it. Most gate valves have either a wheel style handle, or a cross style handle. They're prone to not fully closing, so it's not unusual for a small trickle of water to make its way downstream. To determine if these valves are partially or fully on, you can open a test port or drain valve downstream to test for water pressure. Be aware that there's often residual water in the system that may drain out, even if water is turned off.
Gate valve in backflow box, wheel handle style (just upstream of backflow assembly)
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Gate valve in backflow box, cross handle style (just upstream of backflow assembly)
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Important note: any of these valve styles may also be used to open and close what are known as "drain valves." Drain valves are simply a length of pipe that ends at open air, with a shutoff valve at the end that can be opened and closed to allow water to drain from an irrigation system as part of the winterization process. When properly installed, drain valves should be downstream of your backflow assembly. If your shutoff valve is attached to piping that's open at one end, you're probably looking at a drain valve, not an shutoff valve.
Less Common Backflow Assemblies
There are a few backflow assemblies we don't see as often in the field, but we want to include photos of them below to help with identification. These are:
- A PVB (pressure vacuum breaker) - note the TWO shutoff handles, TWO test ports, and protective cover screwed over the top. These represent less than 0.5% of the assemblies we see in the field. PVBs need to be at least 12" above all downstream outlets (like sprinkler heads). This above-ground installation is problematic since it makes them prone to freezing, UV damage, and other issues. We recommend replacing failing or freeze damaged PVBs with below-grade DCVAs like the ones here.
- An RPBA (reduced pressure backflow assembly) - these are designed for higher-risk applications, and their main identifying feature is a relief valve on the bottom of the assembly. Under normal operating conditions, this valve responds to sudden changes in water pressure by releasing water outside the assembly. Due to the installation requirements for RPBAs, they're often installed indoors or above-ground in an insulated outdoor box to protect them from freezing.
- A DCDA (double check detector assembly) or RPDA (reduced pressure detector assembly) - these are often used on fire lines. They consist of a large main backflow assembly (often 2-12"), along with a bypass loop (3/4-1") with a smaller bypass backflow assembly and a bypass meter. This provides backflow protection without the need for a large, costly water meter on a line without regular water usage. The bypass meter (also known as the "detector" meter), is there to detect leaks or usage downstream. We usually test and report on both the main assembly and the bypass assembly, and also take a meter reading for your water district's records.
PVB
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PVB in the field
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RPBA
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DCDA (RPDAs look very similar)
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