Why removing turf saves water
Outdoor watering is one of the largest controllable uses of water at most homes and businesses. The U.S. EPA's WaterSense program estimates that landscape irrigation accounts for roughly a third of all residential water use nationwide, and much more than that in dry climates during summer. Turfgrass is usually the thirstiest part of a landscape, because it's watered over its entire surface and, depending on the species, needs close to as much water as a well-watered agricultural crop.
Replacing turf with plants suited to the local climate, or with a surface that needs no irrigation at all, cuts that demand directly. How much it cuts depends on three things: how much water your climate calls for in the first place, how thirsty your current turf is, and how thirsty the replacement will be. This calculator combines those three factors into one estimate.
| Landscape type | Relative water need | Notes |
|---|---|---|
| Cool-season turf | Higher | Fescue, bluegrass and ryegrass generally need more water than warm-season species. |
| Warm-season turf | Moderate to higher | Bermuda, zoysia and St. Augustine typically use less water than cool-season turf, but still cover the full area. |
| Climate-adapted or native plants | Lower | Once established, many need only occasional supplemental water. |
| Artificial turf, mulch or hardscape | None to minimal | No routine irrigation, though some surfaces are occasionally washed down. |
The lawn watering by grass type chart breaks this down by individual species.
How this calculator works
The calculator finds the difference in water need between your current turf and your replacement planting, applies that difference to your local reference evapotranspiration (ETo), and converts the result to a volume and a dollar figure.
1. Depth difference
Depth difference
Depth difference = Turf crop coefficient (Kc) − Replacement plant factor
If the replacement needs as much water as the turf or more, the difference is treated as zero. Removing turf for an equally thirsty replacement doesn't save water in this model.
2. Water saved per year
Reference ET, in depth per year, is scaled by the depth difference and your area. The unit conversion depends on which units you're using.
US units
Gallons per year = Area (sq ft) × Reference ET (in/yr) × Depth difference × 0.623
0.623 converts inches of depth over square feet to gallons (144 ÷ 231), the same conversion used for any lawn watering estimate.
Metric units
Liters per year = Area (m²) × Reference ET (mm/yr) × Depth difference
One millimeter of water over one square meter is exactly one liter, so no extra conversion factor is needed.
3. Money saved
Money saved per year
Money saved = (Water saved ÷ 1,000) × Water rate
Rate is entered per 1,000 gallons (US) or per cubic meter (metric); 1,000 liters equals 1 cubic meter, so the same formula works in both unit systems.
4. Payback period
Payback period
Payback (years) = (Project cost − Rebate) ÷ Money saved per year
Shown only once a project cost is entered. A rebate equal to or larger than the project cost brings payback to zero, not a negative number.
Results are rounded to a sensible level, because reference ET and plant factors are themselves typical values rather than site measurements. For a straightforward depth-to-volume conversion on its own, see the inches of water to gallons calculator.
When this calculator isn't the right tool
It estimates savings from removing turf entirely. Use a different approach for:
- Keeping your lawn but reducing its water use, such as with weather-based scheduling. See the smart controller savings calculator.
- Switching sprinklers to drip irrigation without removing the plants. See the drip conversion savings calculator.
- A full water budget across a mixed landscape with several plant zones. See the landscape water budget calculator.
- Designing the new planting's irrigation once you've decided to convert. See the drip irrigation calculator.
Turf removal savings example
A homeowner is removing a 500 sq ft strip of cool-season fescue lawn and replacing it with low water-use native plants. Their local reference ET is 45 inches per year, their water rate is $7.00 per 1,000 gallons, the project costs $2,000, and their water agency offers a $500 rebate.
- Depth difference: 0.8 (cool-season turf) − 0.2 (low water-use plants) = 0.6.
- Water saved: 500 × 45 × 0.6 × 0.623 ≈ 8,416 gal, shown as about 8,420 gallons per year.
- Money saved: 8.416 (thousands of gallons) × $7.00 ≈ $58.91, shown as about $59 per year.
- Net cost after rebate: $2,000 − $500 = $1,500.
- Payback: $1,500 ÷ $58.91 ≈ about 25.5 years.
The same calculation in metric
A 100 m² area of warm-season turf, converted to low water-use plants, in a climate with 900 mm of annual reference ET, a $3.50 per m³ water rate, a $2,000 project cost and a $500 rebate:
- Depth difference: 0.5 (warm-season turf) − 0.2 (low water-use plants) = 0.3.
- Water saved: 100 × 900 × 0.3 = 27,000 L, shown as about 27,000 liters per year.
- Money saved: 27 m³ × $3.50 = $94.50, shown as about $95 per year.
- Net cost after rebate: $2,000 − $500 = $1,500.
- Payback: $1,500 ÷ $94.50 ≈ about 15.9 years.
Both examples show a payback measured in years rather than months, which is typical: water savings alone rarely cover the full cost of a landscape conversion quickly, especially where water is inexpensive. A larger rebate, a higher water rate, or a bigger gap between the turf and replacement's water needs all shorten it.
Turf and replacement plant water needs
The calculator's turf and replacement categories are built on two established ideas. The FAO-56 crop coefficient (Kc) method, developed by the UN Food and Agriculture Organization, describes how much a plant needs relative to reference ET. WUCOLS, the Water Use Classification of Landscape Species developed by the University of California, applies a similar idea to landscape plants, grouping them into water-use bands: very low, low, moderate and high.
| Category | Typical factor | Source range |
|---|---|---|
| Cool-season turf | 0.8 | WUCOLS "high" water use, about 0.7–0.9. |
| Warm-season turf | 0.5 | WUCOLS "moderate" water use, about 0.4–0.6. |
| Moderate water-use plants | 0.5 | WUCOLS "moderate" water use, about 0.4–0.6. |
| Low water-use / native plants | 0.2 | WUCOLS "low" water use, about 0.1–0.3. |
| Artificial turf, mulch or hardscape | 0 | No routine irrigation once installed. |
These are typical midpoints for broad categories, not exact figures for every species or cultivar. Local WUCOLS regional plant lists, a landscape professional, or your water agency's rebate plant list can narrow the number for a specific planting design; use the custom option to enter it directly.
Using your results
Measuring your turf area
Measure only the section you intend to convert, not your whole property. For an irregular lawn, break it into rectangles or triangles, calculate each one, and add them together. Leave out areas you're keeping as turf, and any beds, paths or paving already inside the boundary.
Finding your reference ET
Reference ET varies by climate and season; this calculator uses an annual figure. CIMIS stations serve California; other states typically have a comparable agricultural weather network or extension publication. If a station isn't nearby, the reference ET calculator can estimate a value from basic weather inputs.
Choosing a realistic replacement category
New plantings, including low water-use and native species, typically need regular watering for the first one to two growing seasons while roots establish. This calculator estimates steady-state savings once the planting is established, so your first-year water bill may not drop by the full amount shown.
Common mistakes
- Skipping the rebate program's rules. Many require pre-approval, photos before and after, a minimum converted area, or a list of acceptable replacement plants.
- Leaving out irrigation costs for the new area. Drip lines, emitters and a controller zone for the replacement planting are a real cost that a rebate alone may not cover.
- Assuming permanent zero water for hardscape. Artificial turf and some hardscape are periodically hosed down to remove debris or allergens, which this calculator doesn't include.
Check local rules first. Some water utilities and municipalities regulate how much impervious surface or artificial turf is allowed, and stormwater rules can apply to hardscape conversions. Confirm these before starting work.
What changes your savings
The same square footage can save very different amounts of water and money depending on these factors.
| Factor | Effect | What to adjust |
|---|---|---|
| Local climate (ETo) | Hotter, drier and windier climates have higher reference ET, so the same conversion saves more water. | Use your actual local ETo, not a distant or average figure. |
| Existing turf type | Cool-season turf typically needs more water than warm-season turf. | Match the turf type field to what's actually growing. |
| Replacement choice | A lower water-use replacement produces a larger depth difference and more savings. | Compare low, moderate and no-irrigation options. |
| Current irrigation efficiency | Runoff, wind drift and uneven coverage waste water beyond what this calculator estimates. | Check your sprinklers with the distribution uniformity calculator before assuming this is your ceiling. |
| Water and sewer rate structure | Tiered or seasonal rates change what a given volume of savings is worth. | Use your highest-tier rate for a more realistic dollar estimate. |
| Rebate program rules | Rebates often require pre-approval, a minimum area, or specific replacement plants. | Confirm your local program's requirements before starting work. |
Frequently asked questions
How much water does removing a lawn actually save?
It depends on your climate, how much water your current turf needs, and what you replace it with. This calculator multiplies your area by your local reference evapotranspiration (ETo) and the difference between your turf's crop coefficient and your replacement planting's water-use factor, the same evapotranspiration-based approach used to estimate landscape water budgets. Enter your own numbers to get a site-specific estimate rather than a national average.
Where do I find my area's reference evapotranspiration (ETo)?
California properties can use CIMIS, the California Irrigation Management Information System; many other states publish similar data through a state agricultural weather network or university extension service. If you can't find a local station, the reference ET calculator estimates it from weather data you enter.
What is a crop coefficient or plant factor, and why does turf usually need more water?
A crop coefficient (Kc) or plant factor is a multiplier, developed from research on plant water use, that adjusts reference ET for a specific plant's needs. Turfgrass is generally classified as a higher water-use planting than climate-adapted or drought-tolerant landscaping under systems like WUCOLS, the Water Use Classification of Landscape Species, which is why swapping it out usually reduces water use.
Does this account for how efficiently my sprinklers apply water?
No. This calculator compares the water each planting needs, not how efficiently your irrigation system delivers it, so it doesn't include losses from runoff, wind or uneven coverage. If your current system is inefficient, your real-world savings from removing turf could be higher than this estimate, and a distribution uniformity test shows how much your sprinklers may be losing.
How is the payback period calculated?
Payback is your project cost minus any rebate, divided by the money you're estimated to save each year. It only accounts for water savings and rebates; it doesn't include other cost differences, like reduced mowing or fertilizer, or the cost of installing irrigation for the new planting.
Will removing turf lower my sewer bill too?
It might, if your water utility bases sewer charges on metered water use rather than a flat fee. This calculator only estimates the savings that come directly from your water rate; check your bill or water provider to see whether sewer charges would drop as well.
What if my replacement landscape still needs some water?
That's normal and expected. Choose moderate water-use plants if your new planting will still be irrigated regularly, or enter your own plant factor with the custom option if you know a more specific value. Reserve the no-irrigation option for artificial turf, mulch or hardscape with no permanent watering.
Can I use this for converting only part of my lawn?
Yes. Enter just the square footage of the section you're planning to convert, not your whole property. The calculator scales directly with area, so converting half your lawn saves roughly half as much water as converting all of it, for the same turf and replacement choice.
Who built and checked this calculator
Licensed Professional Engineer and Irrigation Association Certified Irrigation Designer with more than 20 years in irrigation design, system auditing and landscape water management. Full profile
How this page was checked
- Formulas, unit conversions and both worked examples verified by hand.
- Plant factor and crop-coefficient ranges checked against WUCOLS and FAO-56.
- Payback math checked against the entered project cost and rebate, including the zero-savings and no-cost cases.
Sources
- Allen, R.G., Pereira, L.S., Raes, D., Smith, M. Crop Evapotranspiration – Guidelines for Computing Crop Water Requirements (FAO Irrigation and Drainage Paper 56). Food and Agriculture Organization of the United Nations, 1998. [VERIFY URL]
- University of California Cooperative Extension. WUCOLS IV: Water Use Classification of Landscape Species. [VERIFY URL]
- U.S. EPA WaterSense. Outdoor Water Use in the United States. [VERIFY URL]
- California Department of Water Resources. Model Water Efficient Landscape Ordinance (MWELO). [VERIFY URL]