Burst Irrigation Main, Backflow Preventer Freeze, and Yard Flooding¶

An underground sprinkler main-line rupture or a freeze-cracked brass backflow preventer can rapidly flood a basement, undermine a concrete driveway slab, and rack up a $2,000 municipal water bill in a single afternoon. Unlike an individual broken lawn sprinkler head that only sprays water for 15 minutes when the irrigation timer runs that zone, the irrigation main line and above-ground brass backflow preventer sit under continuous 24/7 municipal street pressure: typically 345 to 690 kilopascals (50 to 100 psi), discharging 60 to 130 liters (15 to 35 gallons) of water every minute around the clock even when the electronic sprinkler controller on your garage wall is unplugged.

Worse yet, a high-pressure underground PVC main rupture beneath a front lawn or driveway washes away cubic meters of compacted sand and clay soil beneath the grass sod or concrete pavement, creating a hollow subterranean cavern (an erosion sinkhole) filled with soupy mud that looks deceptively normal on the surface until a homeowner steps onto the turf and plunges waist-deep into a collapsing pit. Mastering how to isolate the dedicated irrigation shutoff valve so your household toilets and sinks stay running, how to operate a meter-box curb stop safely, and how to prevent cross-connection contamination protects both your property and your drinking water.

Aw bɛ o kɛ sisan¶

1. Stay completely off raised turf domes, bubbling mud, or undercut concrete slabs: If a section of your lawn has risen up like a giant waterbed blister, or if water is gushing from underneath a concrete driveway, sidewalk, or foundation wall, keep children, pets, and adults at least 3 meters (10 feet) back. High-pressure water erodes a deep underground void that can collapse instantly under human weight, and walking near an underground electrical utility transformer box or streetlamp in standing water risks electrocution.
2. Aw kana waati tiɲɛ ka fiyɛlilan nimɔrɔma waati jateminɛ kɛsu bɔ kogo la: Ni ji bɛ ka bɔ ka bɔ nɛgɛ pipe lajɛlen na min bɛ aw ka so kɛrɛ fɛ walima ni a bɛ ka wuli ka bɔ binkɛnɛ fɛnɲɛnamafagalan kɛsu jɛman dɔ la sanga 24 kɔnɔ, ni aw ye ɛntɛrinɛti waati jateminɛnan bɔ garazi kɔnɔ, o tɛna foyi kɛ. O karilen bɛ tansiyɔn basigilen sɔrɔyɔrɔba la kuran zone bɔlɔnw sanfɛ; aw ka kan ka farikoloɲɛnajɛlan dɔ datugu min bɛ kɛ ni masinw ye.
3. Aw bɛ bololabɔlan duguma bolokɔni wuli aw ka dugukolo sanfɛ nɛgɛ kɔkannabɔlan kan degere 90: Aw bɛ taama ka taa nɛgɛso pibiliki lajɛyɔrɔ la min bɛ i n’a fɔ U walima min bɛ i n’a fɔ bɛlɛki, min sigilen bɛ aw ka so kɛnɛma kogo kan (walima ɲɛfɛla bugunw kɛrɛfɛ). Aw bɛ nɛgɛ levitiri bolokɔni duguma minɛ donna pipe jɔlen kan ka a wuli degere 90 (a quarter turn) walasa bolo ka sigi kɛrɛnkɛrɛnnenya la (kɛrɛfɛ) pipe la. O bɛ ji bɛɛ dabila ka taa kɔfɛla bɛlɛkisɛ karilen dɔ la walima duguma forow la segin 3 kɔnɔ ka sɔrɔ ka aw ka so kɔnɔ ji to a la.
4. Aw bɛ Jiko Isolation Valve kɛrɛnkɛrɛnnen datugu aw ka so duguma, jirisunba kɔnɔ, walima dugukolo kɛsu kɔnɔ: Ni pipe karilen don jukɔrɔ nɛgɛ kɔjibɔlan bololanɛgɛ (walima aw ka sistɛmu bɛ ni dugujukɔrɔ da tugulen ye), aw bɛ jiko dadonlan kɛrɛnkɛrɛnnen sɔrɔ: aw ka so duguma kɔnɔ walima utilité so kɔnɔ, jifiyɛlan nɛgɛ pipe bɛ bɔ so jibolisiraba la yɔrɔ min na, walima kɔnɔ santimɛtɛrɛ 15 (insi 6) bulama plastiki datugulan fitinin dɔ kɔnɔ ɲɛfɛla la ji jateminɛyɔrɔ kɛrɛfɛ, ka a faga.
5. Aw bɛ nbɛdaba ji jateminɛnan da tugu ni aw ma se ka jifiyɛlan kɛrɛnkɛrɛnnen sɔrɔ: Ni ji bɛ ka bɔn ka taa aw ka so jusigilan fan fɛ, ni aw ma se ka jibɔlan sɔrɔ miniti fila kɔnɔ, aw bɛ taa ɲɛfɛ ka taa municipal ji jateminɛnan dingɛ la nbɛda da la (walima aw ka so kɔnɔ soba jibɔlan da tuguyɔrɔ la, ka kɛɲɛ ni jifiyɛlan tee bolow bɛ faga yɔrɔ min na) ani ka jibɔlan kunba wuli ka a kɛ waatibolodacogo la (walima aw bɛ mɛtɛrɛ dawolo jɔyɔrɔ wuli degere 90 ni fɛn dɔ ye) walasa ka sanjiba jɔ joona.
6. Aw bɛ aw ka so duguma ni wuluwulu yɔrɔ lajɛ joona ni jusigilan kogo bɛ ji bɔ: Ni ji jɔra ka woyo, aw bɛ aw ka so duguma kogow, finɛtiri kɔlɔnw, ani... sump pɔnpe basikɛti o yɔrɔnin bɛɛ, i n’a fɔ jiko ji litiri ba caman minnu bɛ i ka so kɛrɛfɛ dugukolo fa, olu bɛ to ka ji jilama wajibiya ka tɛmɛ jusigilan karilenw fɛ lɛrɛ damadɔ kɔnɔ.

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Tactical decision tree for sprinkler main ruptures and backflow bursts¶

Aw bɛ baara kɛ ni nin baarakɛcogo jatebɔsɛbɛn ye walasa ka jibɔyɔrɔ jira ani ka jibɔyɔrɔ tigitigi datugu min bɛ sanjiba jɔ ka sɔrɔ aw ma du kɔnɔ pɔnpew bɔnɛ ni aw bɛ se.

flowchart TD
    Start["Gushing Yard Water, Geyser, or Flooding Lawn Detected"] --> ElecHazard{"1. Is water bubbling near a power transformer, downed wire, or deep sinkhole?"}
    ElecHazard -->|"Yes: Electrical or Collapse Hazard"| KeepBack["Stay 3m (10 ft) Back; Do Not Step on Raised Turf Blisters; Call Utility or 911 / 112 / 999"]
    ElecHazard -->|"No: Safe to Approach Shutoff"| LeakLocation{"2. Where is the water gushing from?"}
    LeakLocation -->|"A. Spraying from Brass Bell/Pipe on Side of House (Backflow Preventer)"| CheckBelowHandle{"Is the crack ABOVE or BELOW the lower metal lever handle on the brass unit?"}
    CheckBelowHandle -->|"Crack is in Top Bell or Above Lower Handle"| TurnBackflowHandle["Turn Lower Lever Handle 90 Degrees (Crosswise to Pipe) to Stop Water Instantly"]
    CheckBelowHandle -->|"Crack is in Pipe BELOW the Lower Handle"| FindIsoValve["Close Dedicated Irrigation Shutoff Valve (In Basement, Crawlspace, or Yard Round Box)"]
    LeakLocation -->|"B. Bubbling Up from Underground Lawn, Driveway, or Green Valve Box"| SingleOrMain{"Does it stop when you turn the Garage Sprinkler Timer to OFF?"}
    SingleOrMain -->|"Yes: Stops when timer is turned OFF"| StuckSolenoid["Stuck Electric Zone Valve: Tap Solenoid, Flush Diaphragm, or Leave Timer Off"]
    SingleOrMain -->|"No: Runs 24/7 Even with Timer Unplugged"| TryBackflowFirst["Close Lower Handle on Brass Backflow Preventer First; Wait 60 Seconds"]
    TryBackflowFirst --> DidItStop{"Did closing the Backflow Preventer stop the underground leak?"}
    DidItStop -->|"Yes: Leak is Downstream of Backflow"| KeepHouseWater["Leave Backflow Handle Closed; Your Indoor House Toilets & Sinks Remain ON"]
    DidItStop -->|"No: Leak is Upstream Between Meter & Backflow"| FindIsoValve
    FindIsoValve --> IsoFound{"Did you find and close the Irrigation Isolation Valve?"}
    IsoFound -->|"No: Cannot Find or Valve Seized"| CurbShutoff["Close Street Water Meter Valve (Curb Stop) with Meter Key/Wrench or Call Water Utility"]

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Understanding your home's irrigation plumbing layout (So you don't lose indoor water)¶

When an outdoor sprinkler pipe bursts, panicked homeowners often shut off the main water valve inside their house, only to discover two things: first, their indoor toilets and showers are now completely dry, and second, the outdoor yard geyser is STILL spraying full blast.

Why does shutting off the indoor house valve often fail to stop a yard sprinkler leak? Because in warm and temperate climates (such as the Southern and Western United States, Australia, and Mediterranean Europe), the underground irrigation line is tee'd off the main water line out in the front yard right next to the street water meter, before the pipe ever enters your house. Conversely, in cold northern climates with deep winter frost lines (such as Canada, the Northern and Midwest United States, and the United Kingdom), the irrigation pipe usually branches off inside the heated basement or utility room right after the indoor water meter.

Use this regional comparison table to locate your exact irrigation shutoff valves in under 60 seconds:

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Step-by-step: How to shut off every type of irrigation and backflow leak¶

Scenario 1: Water is gushing from the brass bell on the side of your house (Freeze-Cracked Backflow Preventer)¶

Every modern lawn sprinkler system is legally required to have a Backflow Preventer: a heavy brass valve assembly that prevents stagnant lawn water, fertilizers, weed killers, and dog waste from being sucked backward into your family's drinking water pipes if municipal street pressure drops. The three common residential types are the Pressure Vacuum Breaker (PVB) (has a round brass dome or bell on top), the Reduced Pressure Zone (RPZ) assembly (has two inline check valves with a downward relief port in the middle), and the Double Check Valve Assembly (DCVA) (often buried in a rectangular box in the yard).

When an unexpected autumn or spring freeze hits before the sprinkler system is winterized, ice expands inside the brass body with over 200,000 kilopascals (30,000 psi) of force, either blowing out the internal plastic bonnet under the top metal bell or cracking the cast-brass side wall open. As soon as the morning sun thaws the ice plug, a fountain of water shoots out of the brass unit.

1. Inspect the two flat metal lever handles on the brass backflow preventer:
2. Every PVB and RPZ backflow preventer has two quarter-turn ball valves built directly into it: Valve #1 (the Inlet Shutoff) on the vertical input pipe coming up from the ground or wall, and Valve #2 (the Outlet Shutoff) on the pipe heading back down to the lawn.
3. See where the water is spraying from relative to Valve #1 (the lower inlet handle):
4. If water is shooting out from under the top metal bell cap, from the middle relief port, or from a crack ABOVE the lower lever handle: Grab the lower metal lever handle (Inlet Valve #1) and turn it 90 degrees clockwise so the handle stands perpendicular (forming a cross "+") to the pipe. The geyser will stop in two seconds, and your indoor house water remains completely unaffected.
5. If the brass body or copper pipe is cracked BELOW the lower lever handle: Turning the handle on the backflow preventer will not stop water spraying from below it. Leave that handle alone and go immediately to Scenario 2 to close the upstream Irrigation Isolation Valve.

Scenario 2: Closing the dedicated Irrigation Isolation Valve (Basement or Underground Stop-and-Waste Valve)¶

If the pipe has ruptured between the water main and the backflow preventer, you must close the upstream Irrigation Isolation Valve:

• In a house with a basement or crawlspace:
• Go down to the basement and find where your main house water line enters through the concrete floor or foundation wall.
• Follow the cold water pipe until you see a 19-millimeter or 25-millimeter (¾-inch or 1-inch) copper or PEX branch pipe teeing off and running up to the ceiling joist on the side of the house where your outdoor backflow preventer is mounted.
• Close the quarter-turn ball valve (turn handle 90 degrees crosswise) or round gate/globe valve wheel (turn clockwise until snug) on that branch pipe.
• In a house without a basement (Underground Yard Isolation Valve / Stop-and-Waste Valve):
• Walk to the brass backflow preventer in your yard and look at the ground directly at the base of the vertical risers, or walk a straight line between your brass backflow preventer and the street water meter box.
• Look for a small round green, black, or purple plastic lid (typically 15 centimeters / 6 inches in diameter) sitting flush with the grass or mulch.
• Pry the plastic lid up with a screwdriver. Look inside with a flashlight: you will see either a PVC or brass quarter-turn ball valve handle at the bottom of the tube, OR a deep square brass stem (a deep-bury Stop-and-Waste key valve) that uses a long steel T-bar key (cross-handle sprinkler key) to turn 90 degrees clockwise.

Scenario 3: How to turn off the main Street Water Meter Curb Valve (When all else fails)¶

If water is flooding your yard or driveway from a ruptured main line upstream of your backflow preventer and you cannot find a dedicated irrigation isolation valve, shut off the Main Street Water Meter Valve:

1. Locate the rectangular Water Meter Box: Walk out to the front edge of your lawn between the sidewalk and the street curb (or in the front planter bed) and look for a rectangular concrete, cast-iron, or heavy plastic cover labeled "WATER" or "WATER METER."
2. Lift the lid safely: Insert a long screwdriver or pliers into the finger hole and pry the lid open while standing back (watch for spiders, wasps, or snakes underneath the lid).
3. Identify the Customer Side vs. the Street Curb Stop Valve:
4. Inside the meter box, you will see the brass water meter in the center with a pipe entering from the street side and a pipe exiting toward your house.
5. Look on the House Side of the meter first: Many modern water meters have a Customer Hand Wheel or Quarter-Turn Ball Valve right on the house side of the meter that you can turn by hand.
6. Using the Brass Curb Stop Valve (Street Side of the meter): On the street side of the meter sits a heavy brass plug valve with a raised rectangular metal tab (wing) on top and a small round padlock hole on the side.
7. Slip the jaws of an adjustable wrench, slip-joint pliers, or a $12 hardware-store T-Bar Water Meter Key over that rectangular brass tab and turn it 90 degrees clockwise (¼ turn) until the rectangular tab sits crosswise (perpendicular) to the pipe and the two small padlock holes line up with each other.

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Yard sinkholes and undermined driveways: assessing structural collapse danger¶

When a 25-millimeter (1-inch) Schedule 40 PVC irrigation main line splits open 45 centimeters (18 inches) underground, it does not always shoot a geyser into the air. Instead, if the clay soil and thick turf roots above the pipe hold together like a rubber blanket, the pressurized water tunnels horizontally underground, liquefying the soil and flushing thousands of kilograms of sand and silt out into the street gutter or down a storm drain.

Warning signs of an active underground washout or yard sinkhole¶

1. The "Waterbed Lawn" Blister (Hydrostatic Turf Dome): The grass sod rises 10 to 30 centimeters (4 to 12 inches) above normal grade into a spongy, undulating dome. Do not step on it or drive a riding lawnmower over it: underneath that 5-centimeter (2-inch) layer of entangled grass roots is a 60-to-120-centimeter (2-to-4-foot) deep pit of liquid mud slurry that can trap a child or pet instantly.
2. Muddy Silt Fans Pouring Over the Sidewalk or Curb: Clear water bubbling out of a lawn usually indicates a shallow broken sprinkler riser near the surface. Thick brown, sandy, or clay-colored mud slurry pouring across your driveway or through expansion joints in the concrete sidewalk means the water jet is actively excavating the structural soil sub-base beneath your hardscape.
3. Hollow Sounding Concrete Driveway or Front Steps: Once water washes out the compacted gravel base under a concrete driveway slab or front porch steps, a 10-centimeter (4-inch) thick unreinforced concrete slab is left hanging in mid-air like a fragile bridge. Walking or driving a 2,000-kilogram (4,400-pound) SUV over an undercut driveway slab will shear the concrete in half and drop the vehicle's wheel axle into the hole.

How to secure and probe a yard washout after turning off the water¶

• Wait 2 to 4 hours for standing hydrostatic water to drain before walking near the cavity: Once the water valve is closed, allow the trapped underground water dome to percolate down through the soil.
• Cordon off the area and tap-test concrete edges with a long steel rod or shovel: Before walking near the washout or parking a car in the driveway, stand on solid dry ground 2 meters (6 feet) back and probe the turf and the soil under the edge of the concrete driveway using a long steel rebar rod, broom handle, or shovel handle. If the rod plunges straight down 45 centimeters (18 inches) with zero resistance or you can slide the shovel blade horizontally underneath the concrete driveway slab, keep vehicles off the driveway and have a concrete stabilization contractor fill the void after the pipe is repaired.

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Single sprinkler zone stuck on vs. main line burst: how to fix a stuck electric zone valve¶

What if only one section of lawn (for example, the five sprinkler heads in the front yard) refuses to shut off and keeps spraying nonstop, even after you unplug the electronic controller timer on the garage wall?

This is not a burst main pipe: it is a Stuck-Open Electric Zone Valve ("Weeping or Jammed Diaphragm"):

1. Why a sprinkler zone stays stuck on when the timer is unplugged: Every underground sprinkler zone valve opens and closes using water pressure against a rubber diaphragm, controlled by a tiny electromagnetic plunger (the solenoid) on top of the valve. When a tiny grain of sand, pebble, or pipe glue flake gets wedged under the rubber diaphragm seat (or inside the tiny solenoid exhaust port), water pressure can no longer push the rubber diaphragm down to close the valve.
2. How to close or flush a stuck electric zone valve in 2 minutes:
3. Find the rectangular green plastic Valve Box in the lawn: Open the lid and find the valve that is hissing or vibrating as water rushes through it.
4. Step A: Try the Manual Bleed Screw and Solenoid Twist (Flushes out trapped grit): On top of the black plastic valve sits a small cylinder with two electrical wires coming out of it (the solenoid) and a tiny plastic thumb-screw (the manual bleed screw). Turn the solenoid ¼ turn counterclockwise by hand to open the internal water exhaust port for 5 seconds (flushing out any trapped grain of sand), then screw the solenoid snugly clockwise until finger-tight. Do the same with the tiny manual bleed screw.
5. Step B: Turn the Center Flow-Control Handle clockwise (If equipped): Many residential valves (such as Rain Bird, Hunter, and Irritrol models with a cross-shaped handle in the center of the valve top) let you shut the valve down manually by turning that center Flow Control Stem clockwise all the way down.
6. Step C: Clean under the rubber diaphragm: If the zone still runs, shut off your main brass backflow preventer handle for 5 minutes, unscrew the 4 to 6 screws (or the unscrewing jar-top ring) on top of the stuck plastic zone valve, lift out the black rubber diaphragm, rinse away the tiny pebble stuck underneath it, inspect the rubber for tears, and screw the top cap back on.

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Protecting drinking water from cross-connection contamination¶

Whenever an underground irrigation pipe ruptures or a backflow preventer cracks, there is an immediate public health rule you must follow:

• Never bypass a broken brass backflow preventer with a garden hose or straight piece of PVC pipe: Every year, well-meaning homeowners remove a freeze-cracked $200 brass backflow preventer and glue in a $3 piece of straight PVC pipe "just for a few days" to water their lawn. Doing this is both illegal under plumbing codes and potentially dangerous: if a fire hydrant opens down the street or a city water main breaks, negative siphon pressure in the street main can suck hundreds of liters of stagnant underground sprinkler water, laced with lawn pesticides, systemic herbicides, E. coli from pet feces, and roundworm parasites, directly backward into your kitchen sink faucets and neighborhood water main.
• What to do if you need to restore indoor house water while waiting for a plumber to fix an irrigation pipe: If your irrigation system had no separate isolation valve and you had to shut off the main street water meter to stop an outdoor sprinkler pipe leak, any hardware store carries an $8 brass or PVC Threaded Cap or SharkBite Push-to-Connect End Cap (in 19-millimeter / ¾-inch or 25-millimeter / 1-inch size). Cut or unthread the broken outdoor irrigation pipe cleanly, push or thread the solid end cap onto the supply pipe stub, wait the required cure time if using PVC solvent cement, and turn your main house water meter back on so your family has safe indoor drinking water and flushing toilets while the yard system remains safely capped off.

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Preventative checklist: winterizing a backflow preventer in 3 minutes¶

Over 90 percent of burst brass backflow preventers happen during the first unexpected overnight frost of autumn or a late spring cold snap before a full compressed-air blowout. You can drain and freeze-proof your above-ground brass backflow preventer in 3 minutes using the "45-Degree Isolation and Drain Method":

• Step 1: Shut off the upstream Irrigation Isolation Valve (either inside your basement or in the small round underground stop-and-waste box in the yard). If your basement valve has a tiny brass waste cap on the side, place a bucket under it and loosen the cap to drain the vertical pipe.
• Step 2: Open the two small brass Test Cocks on the side of the Backflow Preventer to a 45-degree angle: Use a flathead screwdriver to turn both tiny slotted brass spigots halfway (to a 45-degree angle) so air enters and trapped water drains from the brass chamber.
• Step 3: Turn BOTH main ball-valve handles on the Backflow Preventer to a 45-degree angle (Half-Open / Half-Closed): Never leave ball valves 100 percent closed (90 degrees) or 100 percent open (0 degrees) over the winter, because a tiny pocket of water stays trapped between the chrome ball and the outer brass housing wall and splits the brass body when frozen. Leaving both handles and test cocks at 45 degrees vents the internal ball cavity to open air.
• Step 4: Open an outdoor manual drain petcock or run one sprinkler zone on the timer for 60 seconds to relieve hydrostatic pressure in the riser pipes, then cover the unit with an insulated winter pouch.

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Ɲininkali minnu bɛ kɛ tuma caman na¶

Why is water still gushing from my yard or backflow preventer even after I turned off the main water valve inside my house?¶

In most warm-climate and slab-on-grade homes, the underground lawn sprinkler supply line branches off the main municipal water line **out in the front yard right next to the street water meter**, before the pipe ever enters your house or garage. Because the irrigation tee is located upstream of your indoor house shutoff valve, closing the valve inside your house only shuts off your indoor sinks and toilets while leaving full street pressure flowing into the broken sprinkler line. To stop the leak, close either the lower quarter-turn handle on the outdoor brass backflow preventer, the dedicated underground irrigation isolation valve (under a small 15-centimeter / 6-inch round lid in the lawn near the meter), or the main street water meter curb valve.

How do I turn off a leaking brass backflow preventer on the side of my house?¶

Look at the two flat metal lever handles attached to the pipes of the brass backflow assembly. When a ball valve handle is parallel (inline) with the pipe, the water is ON. Grab the **lower lever handle (on the inlet pipe coming up from the ground or house wall)** and rotate it **90 degrees clockwise** so the handle sits **perpendicular (crosswise) to the pipe**. As long as the freeze crack is located in the top bell assembly or above that lower handle, turning the lower handle 90 degrees stops the water spray immediately while keeping all indoor household plumbing working normally.

Why did the brass bell on my sprinkler pipe suddenly start spraying water when I turned the water back on after a freeze?¶

Inside the top brass bell canopy of a Pressure Vacuum Breaker (PVB) sits a spring-loaded plastic float poppet and plastic bonnet designed to seal upward against an O-ring only when a sudden rush of full water pressure hits it. First, if the unit was not drained before a freeze, ice likely cracked the internal plastic bonnet or brass body (an easy $25 DIY bonnet replacement kit if the brass body itself is not split). Second, if you turned the water supply valve back on *too slowly*, the internal float poppet never received the strong surge of pressure needed to snap it up against the top rubber seal; try closing the upper outlet valve handle first, then opening the lower inlet valve handle **quickly and all the way** so the sudden pressure surge seats the internal poppet cleanly.

Will my homeowner's insurance or the city water utility pay for a $1,500 water bill caused by an underground sprinkler leak?¶

Standard homeowner's insurance policies generally do not cover the cost of lost water or repairing an underground outdoor irrigation pipe (unless the water flooded into the finished interior of your home). However, almost every municipal water utility in the United States, Canada, the UK, and Australia offers an official **"Once-Every-Few-Years Leak Adjustment / Leak Forgiveness Credit."** Once you turn off the valve and repair the broken pipe, take a photo of the repair and submit your plumber's invoice (or your hardware store receipt for the replacement PVC/backflow parts) to your water utility's customer service billing office; utilities routinely waive 50 to 100 percent of the excess leak water charges and sewer surcharges above your normal monthly average.

Why must ball valves on a backflow preventer be left at a 45-degree angle during winter?¶

A quarter-turn brass ball valve contains a hollow chrome sphere rotating inside a tight brass housing. When the handle is turned fully closed (90 degrees) or fully open (0 degrees), a small crescent-shaped pocket of water remains trapped tightly between the outside of the metal ball and the thin outer brass wall of the valve body. In freezing temperatures, that tiny trapped pocket of water expands by 9 percent into ice and splits the side of the brass valve wide open. Turning both ball valve handles and both small test cocks to a **45-degree angle (half-open)** vents that trapped chamber to the air so any remaining moisture expands harmlessly into the pipe bore without cracking the brass.

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Sosow sɛgɛsɛgɛra¶

• U.S. Environmental Protection Agency (EPA, United States): Cross-Connection Control Manual: Backflow Prevention Assemblies (PVB, RPZ, DCVA) and Protection of Potable Water Supplies.
• Ameriki jiko baarakɛlaw ka tɔn (AWWA, Etazuni & Kanada): AWWA M14 kɔsegin kunbɛnni ni ɲɔgɔndan kɔlɔsili kɛcogo ladilikanw ani sigida jiko danfara sariyaw.
• International Association of Plumbing and Mechanical Officials (IAPMO) & International Code Council (ICC): Uniform Plumbing Code (UPC) and International Plumbing Code (IPC) Section 608 (Protection of Potable Water Supply and Lawn Irrigation Backflow Preventer Installation).
• Irrigation Association (IA, United States) & UK Water Regulations Advisory Scheme (WRAS, United Kingdom): Residential Irrigation System Winterization, Freeze Damage Prevention, and Emergency Main-Line Shutoff Guidelines.
• U.S. Geological Survey (USGS, United States): Anthropogenic Sinkholes and Subsurface Piping Erosion Caused by Pressurized Water Line Ruptures.

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Gafe minnu bɛ tali kɛ o ko la¶

• Burst pipe emergency shutoff and repair
• Frozen pipes: how to thaw safely and prevent bursts
• Flooded basement electrical hazards and pumping
• Sump pump failure during heavy flooding
• Water safety and boil water notices
• Kɔrɔtɔko nimɔrɔw