Water at the Right Place, Right Time, Right Amount

Pure Euphoria Botanicals • Nored Farms • Austin, Texas

1. Introduction

Every irrigation system answers one question: can you deliver the right volume of water to a plant's root zone at the rate the soil can absorb it, on the schedule the plant's physiology demands? The difference between getting that answer right and getting it wrong is enormous. Flood irrigation — still the most common method globally — delivers water at 50–70% application efficiency. That means for every gallon pumped, only 0.30–0.50 gallons reach the root zone. Drip irrigation, properly designed, operates at 90–95% efficiency. Same water source, same crop, radically different outcomes.

The history of irrigation is the history of civilization. Mesopotamian canal systems date to 6000 BCE. The qanat systems of Persia — underground tunnels that moved water by gravity from mountain aquifers to arid valleys — operated continuously for over 2,000 years without any pumping energy. Roman aqueducts delivered pressurized water to farms and cities across an empire. Every one of these systems solved the same physics problem: moving water from where it is to where it needs to be, at a rate the land and crop can use.

Modern irrigation adds precision. We can now match application rates to soil intake rates, schedule deliveries to evapotranspiration demand, automate adjustments based on real-time soil moisture, and inject dissolved nutrients directly into the water stream. But the principles have not changed. Water flows downhill. Friction reduces pressure. Soil absorbs water at a fixed rate determined by particle size and structure. Plants transpire water at rates governed by temperature, humidity, wind, and solar radiation. Design with these physics — not against them — and the system works.

This document covers residential, market garden, and small farm scales. The principles apply at any scale, but the equipment and pipe sizing examples focus on systems from 1/4 acre to 20 acres.

2. Water Sources

Well Water

Wells provide consistent temperature and (usually) consistent quality, but flow rate is fixed by the aquifer and pump. Before designing any system, you need two numbers from your well:

  • Flow rate — gallons per minute (GPM). Run the pump into a container of known volume and time it. A typical residential well produces 5–15 GPM. Agricultural wells range from 20–500+ GPM depending on the aquifer.
  • Static pressure — pounds per square inch (PSI) at the wellhead with the pump running and no downstream flow. Residential systems typically operate at 40–60 PSI. Booster pumps can increase pressure if needed.

Well water often contains dissolved minerals — iron, calcium, manganese — that can precipitate and clog drip emitters. Test the water. Iron above 0.3 ppm and calcium above 50 ppm create clogging risk. Filtration (sand media, disc, or screen) addresses particulate issues. Acidification (sulfuric or phosphoric acid injection) keeps dissolved minerals in solution.

Surface Water

Ponds, creeks, rivers, and canals. Surface water requires filtration at minimum — sand media filters for organic-heavy sources, disc filters for moderate sediment. Algae, organic debris, and silt will destroy a drip system in weeks without proper filtration.

Flow rate from surface sources depends on the pump size and lift height. Total dynamic head (TDH) — the vertical lift plus friction loss in the suction and delivery pipe — determines how much flow a given pump can deliver. Every pump has a performance curve plotting GPM against TDH. Match the pump to the system's actual head requirement, not its maximum rating.

Rainwater Harvesting

Gravity-fed from storage tanks. One inch of rain on 1,000 square feet of roof produces approximately 620 gallons. Storage volume determines how much irrigation you can support between rain events. Rainwater is naturally soft and low in dissolved minerals — excellent for drip systems with minimal filtration (screen filter to catch leaf debris).

Pressure from rainwater tanks depends on elevation. Every foot of elevation above the point of use produces 0.433 PSI. A tank elevated 10 feet delivers only 4.33 PSI — insufficient for most sprinklers (which need 25–45 PSI) but adequate for gravity-fed drip systems with low-flow emitters rated at 3–8 PSI.

Municipal Water

Reliable pressure (typically 40–80 PSI) and consistent flow. May contain chlorine or chloramine. Neither damages plants at municipal concentrations, but chlorine can degrade some drip tape over time. The main limitation is cost — municipal water rates make large-scale irrigation expensive. Backflow prevention is required by code on any municipal connection feeding an irrigation system.

Flow Rate and Pressure Testing

Every irrigation design starts with two measurements from your actual water source:

  1. Available flow rate: Open the source valve fully. Measure GPM with a flow meter or by timing how long it takes to fill a 5-gallon bucket. Never design a system that demands more than 75% of your available flow — this leaves margin for pressure fluctuations and prevents pump damage.
  2. Available pressure: Attach a pressure gauge to the source connection with all valves open and no flow. Record static pressure. Then open flow to the design rate and record dynamic pressure. The difference is your system friction loss at that flow — it tells you how much pressure is available for the irrigation zones.

3. Irrigation Types Compared

Method Application Efficiency Water Distribution Pressure Required Labor Best For
Flood / Basin 40–60% Surface, uncontrolled Gravity / low High Rice paddies, level fields, orchards on flat ground
Furrow 50–70% Surface, channeled Gravity / low Medium Row crops on graded fields
Sprinkler (overhead) 65–80% Aerial spray 25–60 PSI Low Turf, pasture, field crops, frost protection
Drip (surface) 85–95% Point-source at soil surface 8–25 PSI Low Vegetables, orchards, vineyards, raised beds
Sub-surface drip (SDI) 90–97% Below-grade point-source 8–20 PSI Very low Permanent plantings, turf, high-value row crops

Flood and furrow irrigation are ancient, require almost no equipment, and work well on perfectly level ground with cheap water. Their inefficiency comes from surface evaporation, deep percolation past the root zone, and uneven distribution across the field.

Sprinkler systems simulate rainfall. They distribute water relatively evenly over large areas but lose 15–30% to wind drift and evaporation — more in hot, windy climates. They also wet the foliage, which promotes fungal disease in susceptible crops.

Drip irrigation delivers water directly to individual plant root zones through emitters rated at specific flow rates (typically 0.5–2.0 GPH). Almost no water contacts the soil surface between plants, suppressing weed germination and eliminating foliar disease from irrigation.

Sub-surface drip buries the drip line 4–12 inches below the soil surface. Eliminates surface evaporation entirely. Requires careful design to prevent root intrusion into emitters and makes maintenance more difficult since you cannot visually inspect emitter function.

4. Drip Irrigation

Drip is the most efficient irrigation method available for the widest range of crops and landscapes. Understanding its components is essential.

Emitter Types

  • Inline drip tape: Thin-walled polyethylene tube with emitters molded into the wall at fixed spacing (typically 6, 8, 12, or 18 inches). Wall thickness from 4 mil (single-season disposable) to 15 mil (multi-year). Best for annual row crops.
  • Inline drip tubing: Thicker-walled (0.5–0.7 mm) PE tubing with pre-installed emitters. Lasts 10–20 years. Standard for permanent plantings — orchards, vineyards, perennial beds.
  • Button emitters: Individual drip emitters punched into blank PE tubing. Allows custom spacing. Available in fixed-flow and pressure-compensating models.
  • Micro-sprayers and micro-spinners: Small spray heads attached to drip tubing via spaghetti tube risers. Wet a larger area (2–6 foot diameter) than point-source emitters. Used for ground cover, wide-rooted trees, and container nurseries.

Pressure Compensation

Standard (non-compensating) emitters deliver flow proportional to pressure. At the head of a long lateral where pressure is high, they over-deliver. At the tail where friction has reduced pressure, they under-deliver. The result is uneven watering across the zone.

Pressure-compensating (PC) emitters contain a flexible silicone diaphragm that restricts flow as pressure increases. Within their rated range (typically 10–50 PSI), they deliver the same GPH regardless of elevation changes or friction losses. PC emitters cost 15–25% more than non-compensating models. They are worth it on any lateral run longer than 100 feet, any terrain with elevation changes, or any system where uniformity matters — which is most systems.

Spacing and Flow Rates

Emitter spacing depends on soil type and root zone width:

Soil Type Recommended Emitter Spacing Wetting Pattern Diameter
Sand 6–8 inches 8–12 inches (deep, narrow)
Sandy loam 12 inches 12–18 inches
Loam 12–18 inches 18–24 inches
Clay loam 18–24 inches 24–36 inches (wide, shallow)

Sandy soils drain vertically — water moves straight down with minimal lateral spread. Closer emitter spacing compensates. Clay soils spread water horizontally — wider spacing works because the wetting fronts merge underground.

Standard emitter flow rates: 0.5, 1.0, and 2.0 GPH. Lower flow rates are better for clay soils (prevents ponding) and longer lateral runs (less friction loss). Higher flow rates suit sandy soils where you need to fill the root zone before gravity pulls water below it.

Pipe Sizing — Main Line, Sub-Main, and Laterals

A drip system has three tiers of pipe:

  1. Main line: Carries water from the source to the field. Sized to handle total system flow. Typically 1.5–3 inch PVC or PE.
  2. Sub-main (manifold): Distributes water from the main line to individual laterals within a zone. Typically 3/4–1.5 inch PE.
  3. Laterals: The drip lines themselves. Typically 1/2–5/8 inch (16–17 mm) drip tubing or tape.

Lateral length is limited by friction loss. The rule: total friction loss across a lateral should not exceed 20% of the operating pressure. For a system operating at 15 PSI, maximum allowable friction loss across the lateral is 3 PSI.

Example: 1/2-inch drip tubing with 1.0 GPH emitters at 12-inch spacing. Each emitter adds 1.0 GPH of flow demand. At 50 emitters (50-foot run), total lateral flow is 50 GPH (0.83 GPM). Friction loss at that flow in 1/2-inch PE tubing is approximately 1.5 PSI per 100 feet — within the 20% rule at 15 PSI operating pressure. Double the run to 100 feet (100 emitters, 1.67 GPM) and friction loss climbs to roughly 5 PSI — exceeding the 20% limit, causing the tail-end emitters to deliver significantly less water. Solution: use 5/8-inch tubing, reduce emitter flow to 0.5 GPH, or split into two shorter laterals fed from both ends.

Filtration

Every drip system needs filtration upstream of the emitters. Emitter orifices are small — typically 0.5–1.0 mm — and clog readily.

  • Screen filters: Simple, inexpensive. Effective for clean water sources (municipal, well). 120–200 mesh for standard emitters.
  • Disc filters: Stacked grooved discs. Better than screen filters for organic-laden water. Self-cleaning models available.
  • Sand media filters: Tanks filled with silica sand. Required for surface water with high organic or algae content. Most expensive but most effective.

Filter sizing rule: the filter must handle the zone flow rate at less than 5 PSI pressure drop when clean. Check and clean filters frequently — a clogged filter starves the entire system.

Pressure Regulation

Most water sources deliver pressure higher than drip system operating range. A pressure regulator downstream of the filter reduces and stabilizes pressure to the design point (typically 10–25 PSI for drip). Preset and adjustable models are available. Install after the filter and before the first lateral takeoff.

5. Sprinkler Systems

Head Types

  • Impact sprinklers: The classic rotating head driven by a spring-loaded arm deflecting off the water stream. Radius 25–45 feet. Flow rates 2–8 GPM. Durable, repairable, tolerant of dirty water. Ideal for pasture, field crops, and large garden areas.
  • Rotor heads: Gear-driven, pop-up heads common in residential and commercial landscapes. Radius 15–50 feet depending on nozzle. Flow rates 1–10 GPM. Quieter than impacts, more uniform distribution, but less tolerant of sediment.
  • Spray heads (fixed pattern): Pop-up heads with fixed spray patterns — full circle, half circle, quarter circle, or strip patterns. Radius 4–15 feet. Flow rates 0.5–3 GPM. High precipitation rates (1.5–2.0 inches per hour) mean short run times to avoid runoff on tight soils.

Head Spacing and Uniformity

Sprinkler spacing follows the head-to-head coverage rule: each sprinkler's throw must reach the adjacent sprinkler head. For a rotor with a 30-foot radius, maximum spacing is 30 feet (square pattern) or 26 feet (triangular pattern). Triangular spacing produces better uniformity.

Distribution uniformity (DU) measures how evenly water is applied across the irrigated area. A DU of 0.85 or higher is considered good. Below 0.70, some areas are severely under-watered while others are waterlogged. Poor DU wastes water because you must over-apply to ensure the driest areas receive minimum required moisture.

Factors that reduce uniformity:

  • Wind (use low-angle nozzles in windy areas)
  • Mixed head types on the same zone (never mix sprays and rotors — their precipitation rates differ by 3–4x)
  • Incorrect spacing (too far apart creates dry spots in the pattern overlap)
  • Pressure variation across the zone

Precipitation Rate

The precipitation rate is how fast the system applies water, measured in inches per hour. It determines how long each zone runs and whether runoff occurs.

Precipitation rate = (96.25 x total GPM of heads in zone) / (area of zone in square feet)

Example: Four rotor heads, each flowing 4 GPM, covering a 30 x 30 foot area. PR = (96.25 x 16) / 900 = 1.71 inches per hour.

On a clay soil with 0.15 inches/hour intake rate, this system would need cycle-and-soak scheduling — run 5 minutes, soak 30 minutes, run 5 minutes — to prevent runoff. On sandy loam with 0.75 inches/hour intake, continuous run is fine.

6. System Design

Hydrozone Planning

A hydrozone is a group of plants with similar water requirements served by a single irrigation zone. Mixing high-water and low-water plants on the same zone guarantees that some plants are over-watered and others are under-watered. There is no timer setting that satisfies both.

Design process:

  1. Map your planting areas by water requirement — high, moderate, low, and no irrigation
  2. Assign each area to a zone with matched irrigation method and schedule
  3. Separate sun exposures from shade — full-sun areas may need 2x the runtime of shaded areas with identical plants
  4. Separate soil types — sandy areas drain faster and need more frequent, shorter irrigation cycles

ET-Based Scheduling

Evapotranspiration (ET) is the combined water loss from soil evaporation and plant transpiration. Reference ET (ET₀) is published daily by agricultural weather stations and extension services. Crop ET is calculated by multiplying ET₀ by a crop coefficient (Kc) specific to the plant species and growth stage.

Crop ET = ET₀ x Kc

Example: July in central Texas. ET₀ = 0.30 inches/day. Tomatoes at full canopy, Kc = 1.15. Crop ET = 0.30 x 1.15 = 0.345 inches/day.

For drip irrigation at 90% efficiency: Gross irrigation requirement = 0.345 / 0.90 = 0.383 inches/day, or 2.68 inches per week.

This is the volume your system must deliver to that zone each week to maintain zero soil moisture deficit. Deliver less, and the crop accumulates stress. Deliver more, and you waste water and leach nutrients below the root zone.

Soil Intake Rate Matching

The maximum application rate your system can deliver without causing runoff is dictated by the soil:

Soil Texture Intake Rate (inches/hour) Recommended Max Application Rate
Coarse sand 2.0–6.0 2.0
Sandy loam 0.75–1.0 0.75
Loam 0.50–0.75 0.50
Clay loam 0.20–0.40 0.20
Clay 0.10–0.20 0.10

If your sprinkler system applies water at 1.5 inches per hour on clay loam soil, 80% of the water runs off. The solution is either cycle-and-soak (short run, long pause, short run) or switching to drip irrigation, which applies water slowly enough that clay soils can absorb every drop.

7. Pipe Sizing

Friction Loss

Water moving through pipe loses pressure to friction. The longer the pipe run and the higher the flow velocity, the greater the loss. Two rules govern pipe sizing:

  1. Velocity limit: Keep water velocity below 5 feet per second (fps) in main lines and below 7 fps in laterals. Higher velocities cause water hammer, excessive friction loss, and pipe fatigue.
  2. Friction loss budget: Total friction loss from source to farthest emitter should not exceed 20% of the operating pressure.

Hazen-Williams Formula

The standard formula for friction loss in pressurized pipe:

hf = (4.73 x L x Q^1.852) / (C^1.852 x D^4.87)

Where:

  • hf = friction head loss (feet)
  • L = pipe length (feet)
  • Q = flow rate (cubic feet per second)
  • C = Hazen-Williams roughness coefficient (150 for PVC, 140 for PE/HDPE, 130 for aluminum)
  • D = inside pipe diameter (feet)

In practice, use manufacturer friction loss tables rather than calculating by hand. Every pipe manufacturer publishes tables showing PSI loss per 100 feet at various flow rates for each pipe size.

Quick Sizing Reference

Pipe Size (ID) Max Flow at 5 fps (GPM) Typical Use
1/2 inch 3.5 Drip laterals
3/4 inch 8 Drip sub-mains, small spray zones
1 inch 13 Sub-mains, small rotor zones
1.25 inch 22 Mains, medium rotor zones
1.5 inch 30 Mains
2 inch 52 Large mains, pump discharge
3 inch 115 Agricultural mains

Always size pipe for the actual flow demand of the zone it serves. Oversizing wastes money. Undersizing wastes pressure and creates velocity problems.

Elevation Changes

Every foot of elevation gain between the water source and the point of use costs 0.433 PSI. Every foot of drop gains 0.433 PSI. On sloped terrain, add elevation loss to friction loss when calculating total pressure drop. A system that works on flat ground may fail on a 20-foot slope — that slope alone consumes 8.66 PSI.

8. Controllers and Automation

Basic Timers

Battery-operated or plug-in controllers that open and close zone valves on a programmed schedule. Set start time, run duration, and days of the week. Simple and cheap. The limitation: they deliver the same amount of water whether it rained 2 inches yesterday or the temperature hit 105°F.

Soil Moisture Sensors

Sensors buried in the root zone measure volumetric water content. Connected to the controller, they override scheduled irrigation when soil moisture is above a set threshold. Two common types:

  • Tensiometers: Measure soil water tension (how hard roots must pull to extract water). Accurate in sandy and loamy soils. Less reliable in heavy clay.
  • Capacitance sensors (TDR/FDR): Measure dielectric constant of the soil, which changes with moisture content. Work across all soil types. More expensive but more versatile.

Place sensors at two depths — one in the upper root zone (4–6 inches) to trigger irrigation start, and one at the bottom of the root zone (12–18 inches) to detect over-irrigation (if this sensor stays saturated, you are pushing water below the roots).

Weather-Based ET Controllers

Smart controllers that receive daily ET₀ data from local weather stations (via cellular, WiFi, or onboard weather sensors) and automatically adjust zone run times to match actual crop water demand. During a cool, cloudy week, they reduce irrigation by 30–50%. During a heat wave, they increase it. Over a full season, ET-based controllers reduce water use 15–30% compared to fixed timers with no change in plant health.

These controllers require accurate zone setup — plant type, soil type, slope, sun exposure, sprinkler precipitation rate. Garbage inputs produce garbage schedules.

Flow Meters

Installed on the main line downstream of the backflow preventer. Two functions:

  1. Usage tracking: Measures total gallons applied per zone, per day, per season. Essential data for optimizing schedules and detecting waste.
  2. Leak detection: If the controller expects a zone to flow at 12 GPM and the meter reads 18 GPM, there is a break. Advanced controllers with flow sensing can shut down the system automatically when flow exceeds a programmed threshold — preventing a broken head from flooding a zone for hours overnight.

9. Fertigation

Fertigation — injecting dissolved fertilizer into the irrigation water — delivers nutrients directly to the root zone at the same time as water. No separate application pass, no fertilizer sitting on the soil surface waiting for rain, no waste between rows.

Injection Methods

  • Venturi injector: A constriction in the water line creates a pressure differential that draws concentrated fertilizer solution from a stock tank into the water stream. Simple, no moving parts, no electricity required. The tradeoff: a Venturi injector creates a 20–30% pressure drop in the line, which must be accounted for in system design. Best for small to medium systems.
  • Dosatron (proportional injector): Water-powered, no electricity. Injects fertilizer at a fixed ratio to water flow (e.g., 1:100, 1:200) regardless of flow rate changes. Consistent concentration. More expensive than Venturi but more precise. The standard for commercial greenhouse and nursery operations.
  • Electric injection pump: Diaphragm or peristaltic pump controlled by the irrigation controller. Programmable injection rate. Required for large-scale operations needing precise PPM control.

Fertilizer Compatibility

Not all fertilizers are compatible in concentrated stock solutions. Calcium and sulfate precipitate when mixed. Calcium and phosphate precipitate when mixed. Use two stock tanks if your fertilizer program includes incompatible elements — inject from each tank through a separate injector or at separate points in the line.

Liquid fertilizers with a guaranteed analysis are easiest to work with. Dry soluble fertilizers must dissolve completely — any undissolved particles clog emitters. Agitate stock tanks continuously.

Backflow Prevention

Mandatory. Any connection between a fertilizer injection system and a potable water source must have a reduced-pressure backflow preventer (RP device) or an air gap. This is code, not suggestion. Fertilizer backflowing into a drinking water supply is a contamination event. An RP device is a spring-loaded, dual-check valve assembly with an intermediate relief port — if either check valve fails, the relief port dumps water to the atmosphere rather than allowing reverse flow.

Install the backflow preventer upstream of the injection point. Test annually per local code requirements.

10. Maintenance

Flushing Drip Lines

Drip emitters accumulate sediment, mineral deposits, and biological growth (algae, bacterial slime) over the irrigation season. Flush lateral lines monthly:

  1. Open the far end of each lateral (remove end caps or flush valves)
  2. Run the system until water flows clear from every lateral — minimum 1 minute of clean flow per line
  3. Re-cap all laterals
  4. Flush sub-mains and main lines at the same time

For mineral deposits (calcium, iron), inject phosphoric acid or citric acid at pH 2.0–3.0 and let it sit in the lines for 24 hours before flushing. For biological clogging, inject chlorine at 10–20 ppm free chlorine and flush after 30 minutes.

Winterization

In any climate where temperatures drop below 32°F:

  1. Close the water supply and open all drain valves at low points in the system
  2. Blow out remaining water with compressed air — 40–80 PSI maximum, never exceed the pressure rating of your components. Start at the farthest zone and work back toward the supply
  3. Remove pressure regulators, filters, and Venturi injectors — store indoors
  4. Disconnect and drain backflow preventers if exposed to freezing
  5. Shut off controller or set to rain mode

Residual water in a drip line that freezes will split the tubing. Residual water in a backflow preventer that freezes will crack the body — a $200–500 replacement.

Spring Startup

  1. Inspect all above-ground components for winter damage — cracked pipe, displaced heads, animal damage to exposed tubing
  2. Reinstall filters, pressure regulators, and backflow preventers
  3. Turn on water supply slowly — do not slam valves open. Check for leaks at every connection
  4. Run each zone manually and walk the entire system: check every sprinkler head for proper rotation and coverage, check every drip line for leaks and plugged emitters
  5. Flush all drip laterals (open end caps, run until clear)
  6. Reprogram controller for current-season ET schedule
  7. Check and calibrate soil moisture sensors if installed

Emitter Cleaning

Plugged drip emitters show up as dry spots in the pattern — one or several plants wilting while neighbors are fine. Before replacing emitters:

  1. Remove the emitter from the tubing
  2. Soak in a solution of one part white vinegar to one part water for 2–4 hours
  3. Use a fine wire or pin to clear the orifice
  4. Reinstall and verify flow

Pressure-compensating emitters can be disassembled to clean the diaphragm. If cleaning does not restore flow, replace the emitter — they cost $0.15–0.50 each.

Seasonal System Audit

Once per season, run a uniformity test:

  1. Place catch cups (identical straight-sided containers) at regular intervals across the zone
  2. Run the zone for a measured time (15–30 minutes)
  3. Measure the depth of water in each cup
  4. Calculate the distribution uniformity: DU = (average of lowest 25% of readings) / (average of all readings)

DU below 0.70 means the system has a design or maintenance problem — clogged emitters, pressure issues, or broken components.

11. Sources

  1. USDA-NRCS. Irrigation Guide. National Engineering Handbook, Part 652. United States Department of Agriculture, Natural Resources Conservation Service.
  2. Burt, C.M., Clemmens, A.J., Strelkoff, T.S., et al. "Irrigation Performance Measures: Efficiency and Uniformity." Journal of Irrigation and Drainage Engineering, ASCE, Vol. 123, No. 6, 1997.
  3. Texas A&M AgriLife Extension. Crop Coefficients and Evapotranspiration Data for Texas. AgriLife Research Station Network.
  4. Lamm, F.R., Ayars, J.E., Nakayama, F.S. Microirrigation for Crop Production: Design, Operation, and Management. Elsevier, 2007.
  5. ASAE. EP405.1: Design and Installation of Microirrigation Systems. American Society of Agricultural Engineers.
  6. Allen, R.G., Pereira, L.S., Raes, D., Smith, M. Crop Evapotranspiration: Guidelines for Computing Crop Water Requirements. FAO Irrigation and Drainage Paper No. 56. Food and Agriculture Organization of the United Nations, 1998.
  7. Schwankl, L.J., Hanson, B.R., Prichard, T.L. Maintaining Microirrigation Systems. University of California, Division of Agriculture and Natural Resources, Publication 21637, 2008.
  8. Hunter Industries. Irrigation Technical Handbook. Residential and commercial sprinkler design reference.
  9. Netafim USA. Drip Irrigation Design Manual. Emitter specifications, lateral sizing, filtration requirements.
  10. Hazen, A., Williams, G.S. Hydraulic Tables. Friction loss calculations for pressurized pipe systems.

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