Building a Small-Farm Irrigation Plan: Materials, Costing, and Step-by-Step Implementation

Goal: turn your site into a buildable irrigation plan

This chapter stitches your prior design and scheduling knowledge into a complete implementation package: a zone map, system choices per zone, a quantified materials takeoff, a budget with phases, an installation sequence, commissioning tests, and documentation you can maintain. The capstone deliverable at the end is a one-page plan you can fill in for your own garden or small farm.

1) Create a site map with irrigation zones

A. Make a base map you can measure from

• Start with a simple scaled sketch (graph paper or a digital drawing). Include: water source point(s), pump/pressure regulator/filter location (if used), main paths, beds/rows, greenhouse/high tunnel, orchard blocks, slope direction, and any areas you will not irrigate.
• Add dimensions: bed lengths, row spacing, distance from source to each area, and elevation changes if significant.
• Mark “hard constraints”: places you cannot trench, where hoses must cross paths, and where you need quick-disconnects for equipment access.

B. Draw zones as operational groups

A zone is a group of plants watered together by one valve (or one manual shutoff) and one runtime. On your map, outline zones with labels (Z1, Z2…). Keep zones practical: close together, similar crop needs, similar sun/wind exposure, and compatible irrigation method.

• Zone boundaries should follow plumbing logic: minimize long runs of small tubing and avoid crossing driveways repeatedly.
• Limit zone size to what your water supply can support: if a zone would exceed available flow or pressure, split it into two zones.
• Plan for expansion: leave a “future stub” (capped tee) near likely new beds.

C. Add a zone legend

2) Choose system types per zone (implementation-focused)

You already know the strengths of drip, soaker, overhead, and gravity systems. Here you decide what you will actually build, based on install complexity, durability, and how easily you can verify performance.

Decision checklist per zone

• Access and traffic: Will lines be stepped on, tilled near, or driven over? Favor buried mainline and protected manifolds.
• Filtration sensitivity: If the water source is dirty or algae-prone, choose components that tolerate filtration limits and plan easy filter servicing access.
• Seasonal removal: For annual beds, consider quick-connect headers so drip laterals can be removed before bed prep.
• Verification: Prefer layouts where you can easily measure flow and spot clogs/leaks (e.g., flush ends, visible pressure gauges at key points).

Typical small-farm pattern

• Mainline (buried or protected) from source to a central manifold.
• Manifold with multiple valves (manual or electric) feeding zones.
• Zone submains to each block, then laterals (dripline, micro, or sprinklers).

3) Calculate materials (a practical takeoff method)

Materials planning is easiest when you separate the system into layers: (1) source and headworks, (2) mainline and manifold, (3) zone distribution, (4) application hardware (dripline/emitters/sprinklers), (5) controls and accessories.

A. Use a takeoff worksheet

B. Measuring tubing lengths (repeatable method)

• Mainline length = measured path from source to manifold + manifold to each zone tie-in + 5–15% slack for routing and mistakes.
• Zone submain length = manifold to the start of the irrigated block (often along a path edge) + slack.
• Lateral length (dripline/soaker) = number of rows or bed lines × length per line. Add 1–2 ft per line for connections and end treatment.

Example (bed block): 8 beds, each 50 ft long, 2 drip lines per bed. Lateral = 8 × 2 × 50 = 800 ft. Add 2 ft per line for connections/end: 16 lines × 2 ft = 32 ft. Total ≈ 832 ft (round up to the nearest roll size).

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C. Counting fittings and connectors (count by “nodes”)

Instead of guessing fittings, count connection points on the map.

• Each time a line branches, you need a tee (or a multi-outlet header).
• Each time a line changes direction, you may need an elbow (unless flexible poly can bend within safe radius).
• Each lateral connection needs an adapter (e.g., submain-to-dripline barb) plus a clamp if required.
• Each lateral end needs a flush valve/cap or a figure-8 end clamp.

Example node count: A header feeds 16 drip laterals: you need 16 takeoffs (barb adapters or grommet takeoffs), 16 end clamps/caps, and typically 1 flush point per header section.

D. Valves, timers, and control wiring (what to list)

• Valves: one per zone, plus one master shutoff upstream of the manifold.
• Backflow prevention: list the correct device for your jurisdiction and water source (often required for potable supplies).
• Controller/timer: number of stations ≥ number of electric valves (add 1–2 spare stations if expansion is likely).
• Wire: measure controller-to-valve path length and add slack for service loops; include waterproof connectors.
• Pressure gauges: at least one at headworks and optionally one at the far end of the longest zone for diagnostics.

E. Emitters/sprinklers: count by plant or by spacing

• Row crops with dripline: count by dripline length (already handled in lateral takeoff).
• Trees/shrubs with point-source emitters: count emitters per plant × number of plants, plus 5–10% spares.
• Sprinklers: count heads by spacing grid; list nozzles separately if interchangeable.

F. Build a “spares and consumables” line item

Include: extra couplers, goof plugs, clamps, a short roll of repair tubing, PTFE tape, primer/cement (if PVC), and a few spare emitters/nozzles. These prevent downtime during peak season.

4) Budgeting and prioritizing phased build-outs

A. Organize costs by phase, not by component

Phasing keeps you irrigating something quickly while you refine the rest. A practical approach is to fund the backbone first, then add zones.

• Phase 1 (Backbone + highest-value crops): headworks, mainline to manifold, 1–2 critical zones, basic controller/timer.
• Phase 2 (Expand zones): additional valves, submains, laterals, and improved distribution hardware.
• Phase 3 (Optimization): extra gauges, better filtration, automation upgrades, permanent burial, quick-connect hydrants, redundancy.

B. Budget table template

C. Prioritization rules that work in the field

• Protect yield first: irrigate the crops with the highest revenue or highest failure risk.
• Build the trunk before the branches: invest in mainline/manifold sizing that supports future zones, even if you don’t build them yet.
• Reduce daily labor: prioritize zones that currently require hand watering.
• Choose reliability over complexity in early phases: fewer moving parts, easier troubleshooting.

5) Installation sequence: build from the source outward

Installing in a consistent order prevents rework and makes testing straightforward. The guiding principle is: install and verify each upstream section before adding downstream complexity.

Step-by-step sequence

1. Stake and mark mainline routes, manifold location, and zone boundaries on the ground. Mark crossings and service access points.
2. Assemble headworks at the source (shutoff, backflow device if required, filter, regulator as needed, pressure gauge, and a hose bib/test port if you want one). Keep it accessible for cleaning and winterizing.
3. Install mainline from source to manifold. If burying, trench to appropriate depth for your climate and traffic; if surface-running, protect from UV and crushing where possible.
4. Build the manifold: a header with one valve per zone, plus unions or threaded connections for service. Label each valve (Z1, Z2…).
5. Run zone submains from each valve to its block. Add flush points at low ends where sediment may collect.
6. Install laterals/application hardware: dripline, micro, or sprinklers. Keep ends accessible for flushing and inspection.
7. Add controls: mount controller/timer, connect valves (and wiring if electric), and create drip loops and strain relief for cables.
8. Label everything as you go: valve boxes, zone lines, and controller stations.

Field tips to prevent common rework

• Dry-fit first (especially PVC manifolds) and confirm clearances for valve handles and unions.
• Install isolation points: a shutoff before the manifold and, if practical, a shutoff for each major block.
• Plan for flushing: every zone should have a way to flush debris at the end of the line.

6) Testing and commissioning: verify pressure, flow, and application

Commissioning is not “turn it on and see if it runs.” It is a short set of checks that confirm the system matches your plan and will be diagnosable later.

A. Pressure check (static and operating)

• Static pressure: with all valves closed, read the gauge at headworks. Record it.
• Operating pressure per zone: open one zone at a time and record pressure at headworks; if you have a far-end gauge, record that too. Large drops can indicate undersized lines, excessive elevation change, or restrictions.
• Leak walk: while each zone runs, walk the line and look for geysers, wet spots, and hissing at fittings.

B. Flow verification (compare expected vs actual)

Use a flow meter if installed, or a timed bucket test at a known outlet/test port. Record zone flow rates so you can detect future clogs or breaks.

• Expected flow comes from your emitter/nozzle totals for that zone.
• Actual flow should be close; significant deviation suggests missing emitters, leaks, or pressure issues.

C. Catch-can test (overhead) or emitter output test (drip/micro)

• Catch-can (sprinklers/overhead): place identical containers in a grid, run for a fixed time, measure depths, and look for dry/wet patterns that indicate spacing/nozzle issues.
• Emitter output test: select a few representative emitters (near, middle, far), run for a fixed time into a measuring cup/bag, and compare volumes. Big differences point to pressure variation or clogging.

D. Commissioning record sheet (what to write down)

7) Document the system for future maintenance (as-built package)

Your “as-built” documentation should let you (or a helper) locate, operate, and troubleshoot the system without guessing.

Minimum documentation set

• As-built map: final routes of mainline/submains, valve locations, zone boundaries, and flush points. Note burial depth and any crossings.
• Zone card (one per zone): method, number/type of emitters or heads, expected flow, operating pressure, and runtime notes.
• Controller schedule: station-to-zone mapping and seasonal runtime ranges.
• Parts list: model numbers for filters, regulators, valves, controller, and emitter types.
• Photo log: pictures of manifolds, valve boxes, headworks, and any buried junctions before covering.

Labeling standard (simple and durable)

• Use weatherproof tags on each valve: Z1, Z2, etc.
• At the controller, label stations with the same zone IDs.
• On the map, use the same IDs and include a legend.

Capstone deliverable: one-page irrigation plan (fill-in template)

Copy this template into a document and fill it out for your own site. Keep it to one page by using concise bullets and totals.

1) Site + zone summary

Site name/location: ___________________________   Date: ____________  Version: ________  Drawn by: ____________  Scale: ____________  Water source: ____________________  Notes (slope/constraints): ____________________________________________________________  ZONES  Z1: Area/crops: ____________________  Method: __________  Valve type/location: ____________________  Z2: Area/crops: ____________________  Method: __________  Valve type/location: ____________________  Z3: Area/crops: ____________________  Method: __________  Valve type/location: ____________________  (Add/remove zones as needed)

2) Parts list (materials takeoff)

HEADWORKS  - Main shutoff: ______ qty __  - Backflow device: ______ qty __  - Filter: ______ mesh/model ______ qty __  - Regulator (if used): ______ psi/model ______ qty __  - Pressure gauge(s): ______ qty __  - Test port/hose bib: ______ qty __  MAINLINE + MANIFOLD  - Mainline pipe/tubing: size ____ total length ____ ft  - Manifold fittings/unions: ________________________________  - Valves: size ____ qty ____ (Zone IDs: ____________________)  ZONE DISTRIBUTION  - Submain tubing/pipe: size ____ total length ____ ft  - Tees/elbows/couplers: ____ / ____ / ____  - Flush points/end caps: ____  APPLICATION HARDWARE  - Dripline: spec __________ total length ____ ft  - Point emitters: type ______ qty ____  - Micro-sprays/sprinkler heads: type ______ qty ____  - Stakes/clips: qty ____  CONTROLS + ELECTRICAL (if used)  - Controller: model ______ stations ____  - Wire: type ______ total length ____ ft  - Waterproof connectors: qty ____  SPARES/CONSUMABLES  - Repair couplers ____  - Goof plugs ____  - Extra emitters/nozzles ____  - Clamps ____  - Tape/primer/cement (as applicable)

3) Runtime schedule (by zone)

Controller mapping: Station 1 = Z__  Station 2 = Z__  Station 3 = Z__  (etc.)  BASELINE RUNTIMES (adjust seasonally)  Z1: Days: __________  Start time(s): __________  Runtime: ____ min  Notes: __________________________  Z2: Days: __________  Start time(s): __________  Runtime: ____ min  Notes: __________________________  Z3: Days: __________  Start time(s): __________  Runtime: ____ min  Notes: __________________________

4) Commissioning targets + recorded values

Record after installation and after major changes.  ZONE   Expected flow (gpm)   Actual flow (gpm)   Operating pressure (psi)   Test method   Notes  Z1     ______               ______             ______                   ______       __________________  Z2     ______               ______             ______                   ______       __________________  Z3     ______               ______             ______                   ______       __________________

5) Maintenance checklist (operational)

WEEKLY (in season)  [ ] Walk each active zone during operation; note leaks, dry spots, clogged emitters  [ ] Check filter pressure drop/clean as needed  [ ] Verify controller time/date and station mapping  MONTHLY  [ ] Flush line ends/flush valves for each zone  [ ] Inspect valve boxes/manifold for seepage and corrosion  [ ] Confirm zone flow/pressure is near commissioning values  SEASONAL (start/end)  [ ] Update runtime schedule for season  [ ] Replace worn tubing/emitters/nozzles; restock spares  [ ] Winterize/drain as required; protect headworks and controller  [ ] Update as-built map after any changes