| Account Type | Base number of residents | Landscape Area (LA) | Base water budget — indoor | Base water budget — outdoor | Total water budget |
|---|---|---|---|---|---|
| Residential detached | 4 | 1,300 square feet (0.03 acres) | Number of residents x 50 gpd | ET x Kc x 1.25 x LA | (Indoor x number of days in bill service period) + outdoor |
| Residential condo (attached / detached*) | 4 | 435 square feet (0.01 acres) | Number of residents x 50 gpd | ET x Kc x 1.25 x LA | (Indoor x number of days in bill service period) + outdoor |
| Apartments* | 2 | N/A | Number of residents x 50 gpd | N/A | Indoor x number of days in bill service period |
| Potable irrigation | N/A | Site-specific based on irrigated landscape | N/A | ET x Kc x 1.25 x LA | Outdoor based on bill service period |
| Recycled irrigation | N/A | Site-specific based on irrigated acreage | N/A | ET x Kc x 1.33 x LA | Outdoor based on bill service period |
| Commercial, industrial, institutional | N/A | N/A | Site-specific, adjusted for number of days in a bill service period | Site-specific, based on irrigation needs | Site-specific, adjusted for number of days in a bill service period |
How your water budget is calculated
Water budgets are based on the number of residents, landscape square footage, and actual daily weather and evapotranspiration (ET) data for your area.
ET is the amount of water required for a landscape to be healthy and attractive. Grass is the highest water-using plant in a landscape, while trees and shrubs use far less water.
IRWD’s water budget system assumes that 40% of your landscape is planted with drought-tolerant varieties irrigated with a water-efficient system, such as drip irrigation. If you continue to maintain a lawn on 60% or more of your property, you will likely be over your monthly water budget.
Helpful definitions
Cost of water
This is the charge for the amount of water you use and is based on the costs to purchase water.
Service charge
This is the fixed cost of maintaining the water distribution system (e.g., pipes and treatment plants).