Irrigation Cost Calculator
What does your watering schedule cost in dollars? Combine flow, run time and your utility rate to see the cost of every session, month and season - and what each schedule change saves.
Inputs
Result
Planning estimate - not a substitute for a pressure-tested engineering design.
Formula
Gallons per cycle = GPM × minutes × zones. Monthly gallons = per cycle × runs per week × 4.33. Cost = gallons ÷ 1,000 × water rate.
Example
10 GPM, 15 min, 4 zones, 3 runs/week at $6/1,000 gal: 600 gal per full cycle → 1,800 gal/week (~7,800/month) → about $47/month, roughly $560/year at that schedule. Each trimmed run saves ~$16/month.
Assumptions
- Constant flow per zone; rate is your combined water + sewer effective rate.
- Seasonal adjustment and rain-sensor skips reduce real totals.
- Monthly figure averages 4.33 weeks; yearly assumes the same schedule all year (peak-season schedules cost more).
Limitations
This tool is a planning aid for DIY design and pre-design work. It does not replace an on-site pressure and flow test, a catch-cup uniformity test, or local code and backflow requirements. For steep slopes, long pipe runs, large elevation changes or commercial-scale systems, have a qualified irrigation designer verify the plan before installation.
What This Means
Schedule changes are the cheapest savings: trimming one run per week saves about $16 a month at these numbers, and tiered rates make summer over-watering even pricier. ET-based scheduling (watering to the calculated need instead of a fixed calendar) typically cuts 20-40% - see the Water Budget Calculator for your target.
Next Step
Find the schedule you actually need with the Water Budget Calculator, then rebuild your timer plan with the Run Time Calculator.
Frequently Asked Questions
How much does it cost to run sprinklers?
A typical 4-zone system at 10 GPM, 15 minutes per zone, 3 days a week uses about 7,800 gallons a month - roughly $30-60 a month at combined water/sewer rates of $4-8 per 1,000 gallons. Your exact number depends on local rates and season length.
Why is my irrigation bill higher than this estimate?
Many utilities charge sewer or stormwater fees on irrigation metering, or use tiered rates that push summer usage into expensive blocks. Use your effective summer rate, not the base rate.