Lawn vs low-water landscape: water use calculator
How much water does a lawn actually use compared with the alternatives? This estimates a season’s irrigation for the same area planted different ways, from your climate and water price.
How this is worked out
Plants lose water through their leaves at a rate set mainly by weather: sun, heat, wind and dry air. Weather networks express that as reference evapotranspiration (ETo): what a well-watered grass would use. Each planting uses a share of it: bluegrass close to 80%, buffalograss under half, established low-water shrubs a third or less. Subtract the rain the plants can use, allow for watering that’s never perfectly efficient, and you have the irrigation.
The factors used here are typical values for planning. They’re useful for comparing options, not for setting a controller: for that, use the catch-cup test.