How much does it cost to water a lawn?
An inch of water on a square foot is 0.623 gallons, so an inch over 5,000 sq ft is 3,115 gallons, and at $6 per thousand that inch costs $18.69. The season is that line repeated for every week the lawn needs watering — which is not "an inch a week from April to October": it's half an inch in the shoulder months, an inch through early summer, more in July, nothing when the grass is dormant. The calculator sums the months the planner uses.
Your bill states the rate per 1,000 gallons or per CCF (a hundred cubic feet, 748 gallons). If sewer is charged on every gallon through the meter, add the sewer rate too — it's usually as large as the water rate, and it applies to irrigation unless you have a separate irrigation (deduct) meter. That single toggle is the biggest number on this page.
Gallons and dollars per inch, by lawn size
| Lawn | Gallons per inch | $3 / 1,000 gal | $6 / 1,000 gal | $12 / 1,000 gal |
|---|---|---|---|---|
| 2,500 sq ft | 1,558 | $4.67 | $9.35 | $18.69 |
| 5,000 sq ft | 3,115 | $9.35 | $18.69 | $37.38 |
| 7,500 sq ft | 4,673 | $14.02 | $28.04 | $56.07 |
| 10,000 sq ft | 6,230 | $18.69 | $37.38 | $74.76 |
One inch of irrigation. $3 is cheap municipal water; $6 is typical; $12 is water plus sewer, or an arid-West summer tier. An inch a week for a month is 4.33 of these.
What a whole season costs
The planner's monthly targets for 5,000 sq ft at $6 per thousand, no rain credited — what a timer set correctly, and never touched, would use:
| Month | Cool-season, in/week | Gallons | Cost | Warm-season, in/week | Gallons | Cost |
|---|---|---|---|---|---|---|
| April | 0.5 | 6,744 | $40.46 | 0.4 | 5,395 | $32.37 |
| May | 1 | 13,488 | $80.93 | 0.8 | 10,790 | $64.74 |
| June | 1 | 13,488 | $80.93 | 0.8 | 10,790 | $64.74 |
| July | 1.25 | 16,860 | $101.16 | 1 | 13,488 | $80.93 |
| August | 1 | 13,488 | $80.93 | 0.8 | 10,790 | $64.74 |
| September | 1 | 13,488 | $80.93 | 0.8 | 10,790 | $64.74 |
| October | 0.5 | 6,744 | $40.46 | 0.4 | 5,395 | $32.37 |
| Season | 27.1 in | 84,300 | $506 | 21.7 in | 67,440 | $405 |
Targets from the planner template (extension calendars); warm-season grasses use about 80% of the water. Months not listed are dormant. Subtract whatever rain falls.
| Rate | Cool-season | Warm-season | Cool-season, sewer applies |
|---|---|---|---|
| $3 / 1,000 gal | $253 | $202 | $506 |
| $6 / 1,000 gal | $506 | $405 | $1,012 |
| $12 / 1,000 gal | $1,012 | $809 | $2,023 |
5,000 sq ft, full template, no rain. "Sewer applies" assumes a sewer rate equal to the water rate on every gallon — the common case without a deduct meter.
On 5,000 sq ft of cool-season lawn, the two peak months are $182 of the $506 season at $6 per thousand — and they're the months a cool-season lawn is perfectly capable of sleeping through. Dormancy isn't neglect; it's the grass's own strategy, and it costs nothing. The watering guide makes the case (with the one rule: commit to it — half-reviving is what actually kills turf). No gadget saves $182. Not watering does.
What does a smart sprinkler controller actually save?
Whatever your current timer is wasting — and nothing more. EPA WaterSense says a labeled controller saves "up to 15,000 gallons" a year per home; at $6 per thousand that's $90, and "up to" is doing the work. A controller saves in two ways the calculator models separately: it tapers with the season instead of running the same minutes from April to October, and it skips when rain has done the job. Both savings are measured against the timer you have, so the answer depends on how badly that timer is set:
| Schedule | Inches / season | Gallons | Cost at $6 |
|---|---|---|---|
| Timer left on 3 × 20 min a week on sprays, April–October | 45.5 | 141,623 | $850 |
| The planner template, no rain credited | 27.1 | 84,300 | $506 |
| The template with 2 in of rain a month credited | 13.1 | 40,690 | $244 |
5,000 sq ft, cool-season. 3 × 20 min on 1.5 in/hr spray heads is 1.5 in a week — a very common "set and forget" program. Rain is credited in full, which is the ceiling for any rain sensor or weather-based controller.
Against the set-and-forget timer, the controller saves $606 a year (71%) — and 57% of that is the taper, which a free afternoon with the dumb timer and the run-time calculator gets you too. Against a timer that was already set to the template, in a climate with an inch of rain a month, the controller's saving is the rain skip alone: $131. Same device, same lawn, a 5× difference, decided entirely by what it replaced.
| Annual saving | $75 net (after rebate) | $150 net | $250 net |
|---|---|---|---|
| Timer left on 3 × 20 min all season (sprays), 2 in rain a month — $606 / yr | 1 month | 3 months | 5 months |
| Timer already set to the template, 1 in rain a month — $131 / yr | 7 months | 1.1 years | 1.9 years |
| EPA’s "up to 15,000 gal" — $90 / yr | 10 months | 1.7 years | 2.8 years |
Payback in years = net price ÷ annual saving. Controllers run $100–250; rebates of $50–150 are common (some districts cover the whole unit), which is why the rebate column matters more than the model.
Is a smart controller worth it?
Run your own timer through the calculator and read the panel. The honest pattern: if your timer is a set-and-forget program, yes, easily — the taper alone pays for it in a season, and it also stops the daily-sprinkle habit that grows shallow roots. If you already adjust the timer monthly and turn it off when it rains, the saving is small and the case is convenience and the rebate. And if the calculator shows your timer under-watering the template, a controller will raise your bill — because it will water the lawn properly. That's not a strike against it; it's just not a saving.
Water price decides the rest. At $3 per thousand the same gallons are worth half as much and every payback doubles; with sewer on the meter they're worth twice as much and it halves. Cheap water and a deduct meter is the one combination where the numbers genuinely don't work — and a rebate that covers the unit makes even that moot.
Why is my water bill so high in summer?
Because the sprinklers are on, and the bill can tell you exactly how hard. Take a summer month's gallons, subtract a winter month's (that's the house — showers, laundry, the same all year), and what's left went on the lawn. Divide by your area and 0.623, then by 4.33 weeks, and you're looking at the inches per week your timer actually applies, which is the number to compare with the schedule:
| Extra gallons in a summer month | Inches per week on 5,000 sq ft | At $6 | Verdict |
|---|---|---|---|
| 5,000 | 0.37 | $30 | under the target — fine if it looks fine |
| 10,000 | 0.74 | $60 | under the target — fine if it looks fine |
| 15,000 | 1.11 | $90 | about right |
| 20,000 | 1.48 | $120 | over — taper it |
| 30,000 | 2.22 | $180 | way over — something is wrong |
| 40,000 | 2.97 | $240 | way over — something is wrong |
Summer minus winter usage. Bills in CCF: multiply by 748. The target in peak summer is about 1–1¼ in a week for cool-season turf, 0.8–1 for warm-season; a lawn reading 2 in or more a week has a timer set for sprays running rotor-length sessions, a leak, or a zone that runs twice.
Find the volume charge, not the total: it's stated per 1,000 gallons or per CCF (748 gal), often in tiers where the summer tier — the one irrigation lands in — is the expensive one; use that tier. Then look for a sewer or wastewater volume charge on the same gallons. If it's there and you don't have a separate irrigation meter, tick the box.
How to cut the bill, in order
Priced for the 5,000 sq ft cool-season example at $6 per thousand, largest first. The two biggest depend on your utility and how bad your system is; the next two are free; the gadget is last.
| Lever | Saves a season | How |
|---|---|---|
| Deduct meter, where sewer is billed on the meter | $506 | Removes the sewer half of every summer bill; ask the utility what the meter costs. |
| Fix poor uniformity (DU 0.55) — if the whole system is that bad | $414 | A zone run 1.8× longer to reach its driest quarter uses 1.8× the water. Nozzles, spacing, pressure. |
| Set the timer to the schedule instead of one program all season | $344 | Run-time calculator, once a month. Free. |
| Let it go dormant in July and August | $182 | Commit to it; water ½ in every 3–4 weeks to keep crowns alive. |
| Skip watering when it has rained (1 in a month) | $131 | A $20 rain sensor or a weather-based controller; or look at the sky. |
Each against the full template with no rain. The deduct-meter line assumes sewer equal to the water rate on every gallon. The uniformity line: a zone with a low-quarter DU of 0.55 needs a 1.8× multiplier (capped at 2× in the catch-cup calculator) to keep its driest corner green, so fixing the heads saves the excess.
Sources: planner watering targets adapted from Penn State, University of Maryland, Purdue, Clemson HGIC, UGA and Texas A&M lawn calendars; EPA WaterSense, Irrigation Controllers and the WaterSense rebate finder; AWWA / Circle of Blue water-rate surveys (rate ranges); Colorado State Extension, Watering Established Lawns.