How the Designer designs a system

What the Designer is

The Designer is a rule-based solver, not a learned model. Give it a drawn yard and the tap's numbers and it works through the job in the order a designer would: survey, hydrozones, heads, drip, zones, pipe and valve boxes, manifold, wiring and program, then a commissioning run against every check.

The same yard and the same inputs always give the same design. Each stage explains its choices in up to three plain bullets, and every rule below is also a live check, so a design drawn by hand is held to the same numbers as the Designer's.

The yard is a top-down grid of square cells, 0.5 m on a house block (0.25 m on a bowling green, 1.5 m on an oval). Each cell has a surface (lawn, bed, veggies, pot, paving, building, pool, keep-dry or off the lot), a soil (sand, loam or clay), a sun rating (full, part or shade) and a ground level. Everything is metric: kPa, L/min, mm/h, metres.

Source: src/sim/designer/index.ts, src/sim/hydro/surface.ts

Survey: what the tap can run

Two numbers drive everything: the static pressure (a gauge on the tap, nothing else running) and the flow (the time to fill a 9 litre bucket, averaged over two rounds). The meter size and the service pipe set a ceiling on the flow, whatever the bucket says.

When nothing's been measured

A tap put on the plan without a test carries typical numbers: 450 kPa, 20 L/min, a 20 mm meter and 15 m of copper service. The Designer designs to them, and every screen that shows them labels them “estimate” until the owner types a measured value or plays the bucket test. The design is only as good as those two numbers, and the app says so.

Source: src/sim/hydro/supply.ts, src/game/yardEdit.ts

Hydrozones: what drinks alike

Cells are grouped by what grows there and how much sun they get. Each hydrozone is watered by one emitter family and programmed for its own need.

• Never watered: the building, the pool, keep-dry areas and anything off the lot. No head may stand on them and the pipe router can't cross them. Paving isn't watered either: throw that lands on it counts as overspray.
• Only lawn gets sprinklers. Beds, natives, veggies and pots always go on drip; sprinklers there would soak the paths and the foliage.
• One kind per hydrozone. A lawn-sun hydrozone with more than a quarter of its cells (and more than two) in shade is flagged: “The shade will drown.” Paving inside a hydrozone fails the check; planted cells left out of any hydrozone are flagged.
• One emitter family per zone. Zones are only ever made inside one family and one hydrozone kind, and the one-family check fails any zone that mixes families on a valve.

Source: src/sim/hydro/hydrozone.ts, src/sim/designer/drip.ts, src/sim/stations/hydrozones.ts

Head placement

Each connected patch of lawn is planned on its own. A narrow arm that a 3.2 m disc can't sit in (a side strip off the front lawn) becomes its own patch when it's more than a few cells and runs more than 3 m from the wide part.

Which family, which size

For each patch the Designer lays out several candidates (the top three sizes, each at two spacings; rotors at three) and keeps the best by a single ranking: no dry cells first, then double coverage, then evenness, then fewest heads, then least water on paving.

Spacing and throw: the 85% reach rule

Wind is treated as a reduction. A head only counts as reaching a point within 0.85 × its radius; the water itself is spread over the full radius, because that's where it lands. So for a point to count as covered twice, the neighbouring head has to sit inside 0.85 r: head-to-head, with a margin.

Where heads go, and which way they face

1. Corners first. Every convex and concave corner of the patch outline gets a head.
2. Then the lattice. The patch splits into rectangles and each gets a head-to-head lattice, edges and infill. A curved patch (an oval) takes a lattice over its bounding box with the points outside pulled onto the edge.
3. Arc by the four cells around the head: all four lawn → 360°; two side by side → 180° facing in; one → 90° into it (a convex corner); three → 270° (a concave corner).
4. Keep water off hardscape. That textbook arc is kept only if it throws no water on paving it can't be dialled back from. Otherwise every arc the nozzle offers is tried at every 5° of direction, scoring +1 for each lawn cell, −0.25 for another planted cell and −3 for hardscape; the arc with the least unavoidable hardscape wins, then the most lawn, then the smaller arc.
5. Dial back off the paving. Inside the chosen arc the radius comes back until the counted reach stops short of the nearest hardscape (r ≤ distance ÷ 0.85 − 0.02 m), never past the shortest dial-back above.
6. Patch up. Any cell still dry or single-covered gets the one extra head that fixes the most, repeated. A one-cell nub nothing clean can reach gets the smallest arc aimed straight at it: a little wet paving beats dead lawn.
7. Prune. Heads that add nothing come out, but never so a cell goes dry, never below the double-coverage target, and never taking the lawn's DU below 82.

Matched precipitation

The catalogue's figure is this formula. Every nozzle's listed precipitation is 60 × its full-circle flow ÷ its maximum throw², so what the catalogue says and what the Designer computes agree: rotary nozzles 8.8–10.1 mm/h (the Sweeper 800, 19.6), fixed sprays 39–55, strips 9.8, and gear rotors 3.7–9.6 mm/h (they used to be listed at 15, which their flows never gave).

A matched set gives the same rate at every arc. Rotary nozzles are sold per arc band with flow in proportion to arc. Each gear-rotor size is a matched-precipitation nozzle set: its quarter, half, three-quarter and full nozzles carry a quarter, half, three-quarters and all of the full-circle flow, and a head takes the nozzle for its arc. In the mid-size rotary line a 360° at 6.6 L/min and 6.4 m puts down 9.7 mm/h, the 90° at 1.6 L/min 9.4 mm/h; a corner strip, 1.1 L/min over 4.5 × 1.5 m, 9.8 mm/h, so strips sit on rotary zones' rate. Within a zone, if the highest head rate is more than 1.25× the lowest the matched-precip check warns.

Bodies

Every rotary, spray and strip nozzle goes on a pop-up body, on every design; a gear rotor is its own body. The body is 100 mm in lawn and the nature strip and 150 mm where a head stands in a bed or veggie patch; the 300 mm shrub riser is left to the owner (the yard doesn't record how tall the shrubs are). A spray on a supply more than its best band plus 35 kPa (about 250 kPa working) gets a 210 kPa pressure-regulating body, the cure for misting sprays. With a brand list the body is the cheapest of the owner's brands, else the cheapest of any. A hand-drawn design's parts list gets the cheapest plain 100 mm body under any nozzle that has none, so the list always has a body per nozzle beside the riser.

Strip nozzles

• They run along the long edges of each rectangle of a narrow patch. A strip narrower than one nozzle's throw needs only one edge.
• Both edges are tried; the one that puts less water on hardscape wins. A sliver of lawn between a bed and a patio is watered from the patio side, so the spill lands on the bed.
• Never from an edge hard against a wall, the pool or the boundary: the pipe can't reach it and the spill hits the wall.
• Strip areas need only single coverage; only a dry cell counts against them.

What the checks hold heads to

The Designer aims higher than the check: 90% of the lawn double-covered before it stops adding heads.

Source: src/sim/designer/heads.ts, src/sim/hydro/coverage.ts, src/sim/hydro/nozzles.ts, src/sim/hydro/checks.ts

Distribution uniformity

DU is worked out on the grid, cell by cell, from a modelled spray profile. Each head's water is flat out to 30% of its radius, then tapers in a straight line to nothing at the full radius, scaled so the volume matches its flow. Overlapping heads add.

With this profile, square spacing at 1.0 r gives about DU 90; at 1.33 r there are dry cells and DU falls to about 68. The DU star needs 70 by default (a job can ask more: the bowling green asks 80). On site, the commissioning run adds a nine-cup catch test (see Commission).

Source: src/sim/hydro/coverage.ts, src/sim/hydro/du.ts, src/sim/hydro/score.ts

Zone sizing

Heads are grouped by emitter family × hydrozone kind × tap, and each group is split into the fewest zones that fit three limits: the tap, the pipe and the pressure. A zone's design flow is the sum of each head's flow at its reference pressure; in the pipe network each head then runs at the pressure it really gets (see Pipe).

The pressure cap

The most a zone can carry and still give its far heads the bottom of their best band, for a zone centred at a given distance from the tap:

Splitting a group

Zones are cut by recursive bisection, not grown head by head. The group is cut across its longer side at the flow that leaves ⌊n/2⌋ zones' worth on one side, and each side is cut again until every piece fits. Cuts prefer natural gaps (a path, a gap between lawns, up to 12 m counts) and the line between two patches. A piece still too big splits once more, into as many as its own cap needs. Starting counts from n to n + 10 are all tried and the one that ends in the fewest zones is kept.

The owner's Zones preference

On an owner's yard the Zones station follows their choice; career jobs keep fixed rules (sun and shade apart is a hydrozone lesson there, and the cost star's reference design must not move).

• Balanced first. If its wider, shared zones fail a check the zones could cause, the rules before it (38 m, sun and shade apart) stand instead.
• Fewest is never dearer. A plan with fewer zones is taken only when it fails nothing Balanced doesn't, saves a station and doesn't cost more on the parts list. Wider zones can want sub-boxes, longer laterals and a bigger main; when they would, the design stays at Balanced's count and the card says so: “Fewer zones (9) would cost A$320 more (sub-boxes, longer laterals), so it stays at 10.”
• Up to N is the controller's limit, so it's met whatever it costs; when the tap can't do it the card says the fewest it can (“at 20 L/min you need at least 7”).
• A mixed sun-and-shade zone runs for its area-weighted weekly need.

Span, stations and the night

• Span: a zone's heads fit inside its plan's span (38 m career, 45 m Balanced, 55 m Fewest and Up to N), measured square (width + height of their bounding box), so one valve box in its middle reaches every head. Wider zones (50 m, 60 m, then any) are only allowed when the zones otherwise outnumber the controller's stations, or one tap can't finish inside the watering window. Good starts at 50 m.
• Laterals past 25 m: zones widened to finish inside the night go back to the usual spans if their laterals then run past the sub-box distance (the second-tap note says what the night needs). A zone whose lateral still runs long after its box is re-seated is split once, when the controller has the station: one more zone for its group, or drip zones whose runs start within 20 m of each other.
• Stations: at most 16 (or the job's controller). Too many zones → rotors drop to low-flow nozzles, then a leaner head layout, then the owner's family filter is relaxed and the why card says so. Best whose rotary-everywhere heads and 80% zones would need more than 16 is sized to the controller: the usual head families and full zones, keeping Best's boxes, valves and extras.
• Pressure shortfall: if, once piped, a zone's last head is under its nozzle's minimum — or, while the controller has stations to spare, under its best band — zones within 18 m of it are capped at 80% of that zone's flow and the lot is re-zoned and re-piped (up to six passes).
• Second tap: if zones × the mean run time (summer, cycles included) is longer than the window (8 h overnight by default), the Designer first tries wider zones, then adds a second point of connection. Heads are shared between the two taps in proportion to their capacity, along the line between them; each drip zone goes to its nearer tap.
• Balance (hand-drawn zones): when the heaviest zone of a family is more than 1.5× the lightest, the Zones station suggests the fewest small heads to move.

Source: src/sim/designer/zones.ts, src/sim/designer/index.ts, src/sim/hydro/zones.ts

Pipe

The mainline runs from each point of connection to every valve box and is pressurised whenever the isolation valve is open: 25 or 32 mm PVC Class 12 (or blue-line PE on a job that has it), sized for the largest single zone it carries (zones run one at a time). Laterals run from each zone valve to its heads and only see pressure while the zone runs: 19 or 25 mm LDPE poly (32 mm PVC for a big zone's first run), sized run by run for the flow in that run. A sprinkler zone's lateral is 19 mm at least; 13 mm is for drip feeders and the short tail to a single head.

Sizing: velocity first, on the real bore

PVC is AS/NZS 1477 Class 12 (PN12): the mean outside diameter less two mean walls (DN25: 33.55 − 2 × 1.9 mm). Blue-line is AS/NZS 4130 PE100 PN12.5 (SDR 13.6). Garden LDPE poly is sold by roughly its bore and joined with barbed fittings. Every run takes the smallest size that keeps it at or under 1.5 m/s, sized for the flow its heads draw at the top of their best band (a rotary nozzle at 350 kPa draws 1.12× its reference flow), so a head the regulator leaves near the top can't push it over; the velocity check fails anything faster.

Friction: Hazen-Williams on the real bore

Why not Darcy-Weisbach? On the small laterals (13–25 mm, 5–30 L/min, Reynolds numbers 8,000–25,000) Hazen-Williams with C = 140 lands within 10% of Darcy-Weisbach with the Blasius smooth-pipe friction factor; the tests check it. The fittings allowance is a bigger uncertainty than the choice of formula, so the model keeps one.

Pressure and flow at every head

Best bands in the catalogue: rotary and strip nozzles 280–350 kPa, gear rotors 280–380, fixed sprays 190–215. Drip is judged on its range alone. If a zone's last head is under its minimum, or under its best band, measured with the tap assembly but before the regulator (the regulator can only take pressure away), the Designer upsizes the pipe feeding it: the mainline to 32 mm, laterals 13 → 19 → 25 mm, and after two passes 25 → 32 mm. Up to four passes; anything still short goes back to zone sizing to be split.

Routing

Pipe is routed on the lattice of cell corners as a branching tree from the valve (or the tap) to every head, searched with A*. Each metre costs by what it passes through:

• Share trenches, never fittings. The mainline runs on the lattice line and laterals in lanes 0.12 m and 0.24 m either side of it, so different zones can share a trench but never meet at a fitting. Parallel pipes within 0.3 m count as one trench.
• Hang branches near the valve. A new branch also pays 0.35 × its pipe distance back to the valve, so far heads tee off the trunk near the valve instead of off the far end (shorter reach, less friction).
• Bores. Crossings of the same path within 0.6 m share one bore. Each bore is a labour line on the parts list.
• Heads connect within 0.5 m of the lateral on an articulated riser (swing joint), so a mower strike doesn't snap the pipe.

Source: src/sim/hydro/pipes.ts, src/sim/hydro/network.ts, src/sim/designer/pipe.ts, src/sim/designer/route.ts

Valve boxes and manifolds

A box can sit on any lattice corner the mainline can reach where at least one of the four cells around it is planted, none is the building, the pool or off the lot, and no head or drip start is within 1.5 m. The edge of a path is fine. If the owner has marked a valve-box spot, the Designer uses the nearest clear ground within 8 m of it (1 m clear of emitters).

• Reach: every emitter of a zone within 18 m of its valve (Good 23 m, Best 12 m). A zone out of reach opens a sub-box fed by a mainline extension. The sub-box check warns when any lateral runs more than 25 m from its valve.
• Box sizes: 1 valve → round 150 mm; 2–4 → standard 300 mm; 5–6 → jumbo 500 mm. More than six valves opens another box.
• Manifolds: pre-built 2, 3 and 4-valve manifolds with unions; five valves are a 3 + 2, six a 4 + 2.
• Drain: if the mainline falls more than 0.05 m, a drain tap goes at its low point.

Source: src/sim/designer/pipe.ts, src/sim/designer/manifold.ts, src/sim/stations/manifold.ts

Point of connection

From the tap out: isolation → backflow → filter → regulator → mainline.

• Isolation: a 25 mm ball valve (32 mm when the mainline is 32 mm), so the system can be shut off without the house.
• Backflow: many Australian water authorities rate a buried automatic irrigation system as a medium hazard to the drinking water, so every in-ground system gets a testable device — a testable dual check — at a garden tap as much as at the meter, fitted and tested by a licensed plumber (and tested again every year). The Designer adds the plumber as a labour line and never tells an owner to fit it themselves. A high-hazard job gets a reduced pressure zone device, also plumber-only. A hose-connection vacuum breaker is only for an above-ground hose timer with nothing buried. The note on the device, the parts list and the install guide: check with your water authority; installed and tested by a licensed plumber. Every point of connection must have one: the backflow check fails without it, and warns on a plain dual check or vacuum breaker on a buried system.
• Filter: a 150-mesh screen filter on every point of connection, sprinklers or drip.
• Regulator: fitted when the working pressure would put a head over the top of its best band, or when static pressure is over the rating of anything on that point of connection. The poc-order check fails an unregulated system whose static is over the emitters' maximum.

Sprays on a mixed system sit on 210 kPa pressure-regulating bodies (see Bodies), so one regulator can suit the rotary heads and the sprays still land in their 190–215 kPa band.

A single-zone job run by a battery tap timer skips the box: the timer screws onto the tap (the tap is the isolation), then the backflow (testable, the plumber's, when anything is buried), a regulator if needed, and 19 mm poly to the heads.

Source: src/sim/designer/manifold.ts, src/sim/stations/manifold.ts, src/sim/hydro/checks.ts

Drip

Every drip zone runs off a Drip Control Kit: a 25 mm valve, a 150-mesh filter and a 140 kPa regulator in one, because a filter and regulator at the tap are set for the sprinklers, not the drip. The drip-kit check fails a drip zone on a plain valve.

• Run lengths: each dripline product carries its own maximum lateral run (40 m for 13 mm 1.6 L/h at 300 mm, 75 m for 16 mm 1.6 L/h at 400 mm). Longer runs are split; the drip-run-length check fails any over.
• Flush points: a flush valve at the far end of every run, and an air/vacuum relief at the high point. The drip-flush check fails a dead-ended dripline.
• Zones: one drip zone per kind of planting per tap, under the same 85% cap, grouped by pipe distance so a zone's runs start within 34 m of each other.

Source: src/sim/designer/drip.ts, src/sim/stations/drip.ts, src/sim/hydro/water.ts

Wiring

• 24 V AC from the controller's transformer. Anything on the 240 V side is an electrician's job, and the install guide says so.
• A white common daisy-chained to every solenoid and landed on the controller's C terminal, plus one coloured core per station. Two valves on one station is flagged; if their flows together top the zone cap, it fails.
• Cable per box: direct-burial multi-core, 0.5 mm² cores. Cores needed = valves + 1 common (+ 1 for a master valve). The Designer picks the smallest cable with one spare core from 5, 7, 9 and 13-core. Length is the square distance from the controller to the box plus 2 m of tails, laid in the mainline trench.
• Every underground joint in a gel-filled waterproof connector, two at each valve. The sealed check fails a bare joint.
• Controller: the smallest of 4, 6, 8, 12 or 16 stations with at least one spare (zones + 1). With a flow sensor, a flow-sensing controller.

Source: src/sim/stations/wire.ts, src/sim/designer/manifold.ts

Program

Run times come from each zone's precipitation rate and its planting's weekly need, scaled for the yard's climate and season, and stretched for the zone's uniformity. The table below is Melbourne's (the default).

Season factors: summer 1, spring and autumn 0.6, winter 0.25. Days are summer / spring and autumn / winter.

The yard's climate

The weekly needs are scaled by the region's summer evaporation over Melbourne's. The region comes from the yard's address — the state in it, else the capital nearest the lot — and is Melbourne when the yard has none (a template or a blank block). The program, its card and the controller face say which climate it was worked out for.

• Start: 05:00. Stations run in order; a station's next cycle waits for its soak while the others run.
• Watering window: optional and off by default. When set, the start moves inside it, and anything that runs outside it gets a soft note, never a failure: “Rules change — check your water authority.” No city's rules are stated as fact.
• Also on the controller: seasonal adjust (10–150%), and a rain sensor switch.

Source: src/sim/hydro/water.ts, src/sim/stations/program.ts

Commission

Commissioning fills the mainline, runs every zone from the program and ends with a catch-cup test. Every check that fails plays out on the plan as what you'd see on site (DRIBBLE, UNEVEN, GRIT, NOTHING RUNS), with a one-line reason and the station that fixes it. A design passes when no check is at fail. Warnings are notes worth a look.

• hydrozone-mixedHydrozoneOne kind per hydrozone, no paving inside
• draw-omissionsDrawThe drawn yard matches what's there
• head-to-headHeads≥ 85% double coverage, no dry lawn
• spacingHeadsNearest neighbour ≤ 0.55 × diameter
• oversprayHeadsWater off hardscape (warns)
• zone-flowZonesEach zone ≤ 85% of design capacity
• one-familyZonesOne emitter family per valve
• matched-precipZonesMax ÷ min head rate ≤ 1.25 (warns)
• second-tapZonesAll zones run inside the window (warns)
• velocityPipeEvery run ≤ 1.5 m/s
• pressurePipeEvery head within its nozzle's range; warns outside its best band
• network-connectedPipeEvery emitter traces back to its valve
• dead-endPipeRuns end at a head, cap or flush valve
• shared-fittingPipeZones share trenches, never fittings
• zone-valveManifoldA valve for every zone
• backflowManifoldA backflow device at every connection; testable on a buried system (warns)
• isolationManifoldIsolation before the manifold
• poc-orderManifoldTap assembly in order; regulated when needed
• box-orderManifoldBox order, and valves fit the box
• sub-boxManifoldLaterals within 25 m of the valve (warns)
• drip-kitDripDrip zones on a Drip Control Kit
• drip-flushDripA flush valve at every dripline end
• drip-run-lengthDripRuns within the product's maximum
• valve-wireWireEach valve on its own station
• commonWireCommon to every solenoid and C
• controller-stationsWireEnough stations on the controller
• sealedWireEvery joint gel-sealed

The catch-cup test

Nine cups in a 3 × 3 pattern over the lawn's bounding box, each placed at random within its ninth (seeded, so it repeats) and snapped to the nearest lawn cell. The test runs 15 minutes; each cup's depth is the modelled rate × 15 ÷ 60, and the DU of the nine is shown beside the lawn's DU. The install guide asks the owner to run the same test with real cups.

Stars

• Coverage: lawn DU at or over the target (70 by default) and overspray no more than 5% of the lawn area.
• Hydraulics and code: no check at fail.
• Cost: parts and trench metres each within 10% of the Designer's own design for the same yard.

Source: src/sim/hydro/checks.ts, src/sim/stations/commission.ts, src/sim/hydro/du.ts, src/sim/hydro/score.ts

Good, Better, Best

On an owner's own yard, “Design it for me” offers up to three designs along one line, from “does the job” to “best result”. They are the same Designer with its choices biased, not three designers. Two that come out with the same heads and within 5% on cost collapse into one card.

Sprays on a big lawn were tried as the Good option and dropped: with this catalogue they need two to three times the zones, so they're neither cheaper nor easier. When the lean design still costs more than the usual one (a long lot where one box means twice the trench), Good is the usual design without extras.

DIY difficulty

Source: src/sim/designOptions.ts, src/sim/designer/heads.ts, src/sim/extras.ts

Phasing, required parts and optional extras

An owner can build part of a design now. Each kind of area (lawns, beds, veggies, pots, strips), or any single zone, can be:

• Build now: on this weekend's parts list.
• Later: its capacity stays in the plan: a station on the controller, a core in the cable, an outlet on the manifold (capped; the valve goes on in phase 2) and a 1 m capped stub of its lateral out of the box, so phase 2 never digs up the box, the mainline or the cable trench. Its heads, drip and the rest of its pipe are a separate phase 2 list.
• Leave out: gone. The manifold, box, cable, controller and program are re-fitted without it, and the mainline is trimmed back.

An extra's price is the whole bill with it less the bill without it. A master valve needs a free slot in the main box; when a jumbo box is full, the switch is off and says why.

Source: src/sim/phasing.ts, src/sim/extras.ts

Assumptions and limits

The model is honest about what it simplifies. A supplier or designer should know these before relying on a design.

• DU is geometric. It comes from a modelled wedge profile (flat to 30% of the radius, straight taper to the edge) on a grid, not from a manufacturer's measured catch-can data. Real nozzles' profiles differ, so the figure ranks layouts well but isn't a test result.
• Wind is only the 15% reach allowance. There is no wind speed or direction, no evaporation, and no drift.
• Flow by pressure runs through the pipe network, the pressures and the velocities; zone sizing, precipitation and DU use each nozzle's flow at its reference pressure (280 kPa; sprays 210), which the regulator's setpoint keeps the far heads close to. Throw isn't adjusted for pressure: the catalogue has no throw-by-pressure data.
• Friction is Hazen-Williams on each product's real bore with a C per material and a percentage for fittings, not a loss per fitting. The zone pressure cap assumes a 32 mm PVC mainline and a 6 m lateral; the full network check afterwards uses the real pipe.
• Supply losses come from a small table built around a 20 mm meter, a 15 m service by default and a fixed loss per backflow type. Working pressure is taken at the full design capacity, which is conservative when a zone draws less.
• The program scales fixed weekly needs (Melbourne's, seasonally scaled) by a capital city's January evaporation from Hargreaves' equation, not local daily ET, and doesn't net off rain (the rain sensor does); the tropical north's dry-season peak isn't modelled. It stretches run times by the scheduling multiplier from each zone's modelled DU. Soil intake is one generic figure per soil type.
• Not modelled: pumps, tanks, bores, greywater, frost drainage beyond the low-point drain, and anything imperial.
• The catalogue is invented. Its brands and lines are made up; their numbers are representative of the product types, not copies of any real product.
• Local rules vary. Backflow hazard ratings, which devices are accepted, plumbing codes and watering restrictions differ by water authority and change over time. The Designer treats a buried automatic system as medium hazard (a testable device, fitted and tested by a licensed plumber) and always labels it so; the owner should still check their water authority's current rules. A Sprinklers design is a well-reasoned starting point, not a certified design.