Irrigation Calculator

Most gardens need 1-2 inches of water per week, including rainfall. Vegetables typically require 1-1.5 inches weekly, while lawns need 1-1.5 inches and established trees need deep watering every 2-3 weeks. Hot, dry climates may require double these amounts. Sandy soils need more frequent watering, while clay soils retain moisture longer. One inch of water equals 0.623 gallons per square foot, so a 500 sq ft garden needs 310-620 gallons weekly.

Drip irrigation is most efficient, delivering water directly to plant roots with 90-95% efficiency compared to 50-70% for sprinklers and 40-50% for hand watering. Drip systems reduce evaporation, prevent foliar diseases, and minimize weed growth. They cost $0.50-$3 per square foot installed. Soaker hoses offer similar benefits at lower cost ($0.20-$0.50 per foot). Efficiency savings pay for installation in 2-4 years in most climates.

DIY drip irrigation costs $0.50-$1.50 per square foot for materials. Professional installation runs $1.50-$4 per square foot. Sprinkler systems cost $2-$5 per square foot installed. A 500 sq ft garden drip system costs $250-$750 DIY or $750-$2,000 professionally. Larger systems (1,000-5,000 sq ft) benefit from economies of scale. Smart controllers add $100-$300 but reduce water use by 20-40%.

Calculate weekly water needs (area × inches needed × 0.623 gallons per sq ft per inch), multiply by weeks per season, then by your water rate. For example, 500 sq ft needing 1.5 inches weekly for 26 weeks equals 12,145 gallons. At $0.01 per gallon (typical municipal rate of $5-10 per 1,000 gallons), annual cost is $120. Efficient irrigation can reduce this by 30-50%.

Key factors include plant type (vegetables need more than native plants), climate (hot/dry climates double requirements), season (summer peak vs spring/fall), soil type (sand drains fast, clay retains moisture), sun exposure (full sun needs more), wind exposure (increases evaporation), mulch (reduces needs 25-50%), and plant maturity (established plants need less). Monitor soil moisture and adjust accordingly.

Drip irrigation excels for vegetable gardens, raised beds, rows, and individual plants, offering 90%+ efficiency and disease prevention. Sprinklers work better for lawns, large areas, and overhead coverage, with 50-70% efficiency. Consider drip for water conservation, precise delivery, and low pressure. Choose sprinklers for uniform lawn coverage and ease of installation. Many gardens use both: drip for beds, sprinklers for lawn.

Run duration depends on system output and plant needs. Drip systems typically run 30-90 minutes per zone, delivering 0.5-1 inch per hour. Sprinklers need 20-40 minutes for 1 inch of water. Use catch cans to measure output. Water deeply and infrequently rather than shallow and often. Early morning (4-8 AM) is ideal, minimizing evaporation and disease. Adjust seasonally: more in summer, less in spring/fall.

Payback varies by water costs and system efficiency. In areas with expensive water or mandatory conservation, drip systems pay for themselves in 2-4 years through reduced consumption. They also save 50-100+ hours annually versus hand watering (worth $500-$1,000 in time). Add improved plant health, higher yields, and convenience. Systems lasting 10-15 years provide excellent long-term ROI. Smart controllers accelerate payback through optimized scheduling.

Yes, properly designed automated systems save 20-50% water versus hand watering. Drip irrigation eliminates overspray, runoff, and evaporation. Timers prevent over-watering and ensure consistent schedules. Smart controllers adjust for weather, soil moisture, and plant needs. Hand watering tends toward either over-watering (waste) or under-watering (stress). Automation provides optimal amounts at ideal times, improving both conservation and plant health.

Drip systems need annual flushing, emitter cleaning (check for clogs monthly during season), filter replacement, and line inspection for damage. Sprinkler systems require head cleaning, adjustment, leak checks, and winterization in cold climates. Budget $50-$100 annually for maintenance supplies. Spring start-up and fall winterization are critical. Controllers need battery replacement. Well-maintained systems last 10-15 years; neglected systems fail in 5-7 years. Regular maintenance prevents costly repairs.

In freezing climates, winterization prevents pipe damage. Shut off water supply, drain all lines using compressed air (hire professional or rent compressor), insulate above-ground components, and bring controllers/timers indoors. Drip systems are easiest to winterize (drain and flush). Sprinkler systems need professional blow-out service ($50-$100). Skip winterization risks hundreds to thousands in spring repairs. Warm climate systems need minimal winterization but benefit from off-season inspection.

Smart controllers use weather data, soil sensors, and algorithms to optimize watering schedules automatically. They adjust for rain, temperature, humidity, and seasonal changes. Benefits include 20-40% water savings ($50-$200 annually), convenience, remote control via smartphone, and rebates (many utilities offer $50-$100 rebates). Controllers cost $100-$300. Payback occurs in 1-3 years through water savings alone. Ideal for busy homeowners, travelers, and conservation-minded gardeners.