Enter your irrigation and cost details
Example data table
| Scenario | Zones | Flow (L/min) | Minutes | Days/week | Months | Reduction | Annual water saved (L) | Annual net savings ($) |
|---|---|---|---|---|---|---|---|---|
| Small lawn | 3 | 10 | 18 | 3 | 7 | 20% | ~98,000 | ~$42 |
| Mixed beds | 5 | 12 | 22 | 4 | 8 | 25% | ~288,000 | ~$130 |
| Large garden | 8 | 15 | 25 | 5 | 9 | 30% | ~738,000 | ~$365 |
Example values are illustrative. Your costs and runtime drive results.
Formula used
events = days_per_week × 52 × (months_per_year ÷ 12)minutes = minutes_per_watering × events × effective_zonesliters = flow(L/min) × minuteswater_cost = (liters ÷ 1000) × cost_per_1000LkWh = pump_power(kW) × (minutes ÷ 60)smart = baseline × (1 − reduction%)savings = water_saved + energy_saved − maintenance“Effective zones” is estimated as zones × 0.70 to represent average operation. If your controller runs nearly all zones each cycle, treat effective zones as zones.
How to use this calculator
- Enter your current watering schedule and measured flow rate.
- Add your water and electricity rates from recent bills.
- Set the expected reduction percentage for a smart controller.
- Include controller price, rebate, and any annual upkeep costs.
- Click Calculate savings to view results above the form.
- Download a CSV or PDF summary for records and planning.
Water Use Baseline
Smart irrigation savings start with a reliable baseline. Record typical watering days, minutes per zone, and measured flow. Multiply flow by runtime to estimate weekly gallons. Note seasonal shifts, such as summer peaks and shoulder‑season reductions. Use a recent bill for validation. This calculator converts that baseline into monthly and seasonal totals, so you can compare before and after adjustments with confidence.
Weather-Responsive Adjustments
Smart controllers cut waste by responding to weather and evapotranspiration. When rainfall or cooler temperatures reduce plant demand, schedules are shortened or skipped. Sensor feedback and forecast data can also prevent watering during wind or heat spikes. Shade and mulch can amplify savings. Enter a realistic reduction percentage based on local climate and exposure. Conservative inputs produce steadier budgets, while aggressive values highlight best‑case outcomes.
Soil and Plant Factors
Landscape conditions influence achievable reductions. Sandy soils drain quickly and may need shorter, more frequent cycles, while clay benefits from longer soak and fewer starts. Plant type, slope, and sun hours change demand too. Micro‑sprays and drip lines often save more than high‑flow rotors when tuned correctly. Audit nozzle uniformity before adjusting runtimes. Use your most common zone conditions to avoid overstating savings across mixed beds.
Utility Cost Modeling
Costs depend on more than water rates. Pumps, well systems, or booster stations add electricity use. This tool estimates kWh from pump power and run hours, then applies your energy tariff. If your pump has variable speed, use average running wattage from a meter or label. Include demand charges if they apply. It also separates annual maintenance so the net savings reflect real ownership costs, not just utility bills.
Payback and Investment Planning
Financial planning should include incentives and simple payback. Subtract rebates from purchase price to get net investment. Annual net savings are compared to that investment to estimate payback years, while monthly savings support cash‑flow planning. Consider replacement batteries, valve servicing, and occasional sensor calibration in upkeep costs. Track meter reads each month. Revisit inputs each season to keep projections aligned with garden changes.
FAQs
Q1. How do I estimate the reduction percent?
Start with 10–20% for mild climates and 20–40% for hot, dry regions. Increase if you currently overwater, and decrease if your schedule is already efficient and seasonally adjusted.
Q2. What if my flow rate is unknown?
Use a water meter test: run one representative zone for 10 minutes and record gallons used. Convert to gallons per minute, then apply it across zones as an average.
Q3. Does the calculator work for drip irrigation?
Yes. Drip systems often show higher savings when schedules are optimized. Enter your typical runtimes and a measured drip flow rate from the mainline or zone meter.
Q4. How are electricity costs included?
If you use a pump, enter pump power and runtime. The calculator estimates kilowatt‑hours and multiplies by your energy rate, helping you see combined water and power savings.
Q5. How should I handle rebates or incentives?
Enter the expected rebate as a separate value. The tool subtracts it from the purchase price to compute net investment, which improves payback and ROI calculations.
Q6. Why does payback seem longer than expected?
Savings may be limited by low water rates, short watering seasons, or already efficient schedules. Try updating reduction percent, verified flow rate, and maintenance costs for a more accurate outlook.