Understanding Your Water Budget

Understand how Moulton Niguel’s water budget based rates are designed to allow for efficient water use based on your personalized needs.

We All Use Water Differently

That’s why Moulton Niguel creates a customized monthly water budget for each customer. Below is a breakdown of how Moulton Niguel calculates indoor and outdoor water usage for residential and commercial customers. To understand how changes in your water use can affect your monthly bill, visit our Bill Calculator web page.

The Moulton Niguel Water District approved new rates in January 2022. Read our 2021 Prop 218 notice for detailed information.


Residential water budgets are calculated based on each customer’s landscaped area of their parcel, real-time localized weather data, and the number of residents in each home. These can vary month-to-month based on weather and number of billing days in each cycle. See below for how we calculate both our indoor and outdoor water budgets for our residential customers.

Indoor water budgets for residential locations are calculated using three factors:

1) 55 gallons of water used per person per day

2) the number of people in the household

3) the number of days in the billing cycle

Household sizes are based on Census averages unless updated through the customer Water Budget Modification process.  Based on these averages, a number of people per household is assumed for each account type: four people for single family homes, three people for condominiums, and two people for apartments. Please check your billing statement and contact us if you have a different number than what is stated on your bill. The District has updated the wastewater rate structure to account for cost increases passed through from the South Orange County Wastewater Authority.

Outdoor water budgets for residential locations are calculated using three factors:

  1. Irrigable area per parcel, including pools and spas
  2. Daily evapotranspiration (ET)
  3. Plant factor

Irrigable area is the amount of landscaped area on the property that receives regular watering. Evapotranspiration (ET) is the amount of water that is lost each day due to evaporation and plant transpiration. ET will vary due to factors such as length of day, wind, humidity, and temperature. Lastly, the plant factor equates to the specific amount of irrigation water required by each type of plant in your yard.

Moulton Niguel has developed an ET visualization map tool to illustrate the areas where ET levels are higher, and how it plays a role in your residential outdoor water budget.



Commercial customer water budgets are calculated based on a three-year rolling average of each commercial customer’s monthly use. If your business has separately metered landscape irrigation needs, the outdoor water budget is calculated based on the size of the landscaped area and real-time localized weather data, among other factors, as shown in the Irrigation Budgets section below.

Potable water irrigation water budgets are calculated using a 0.7 plant factor. If recycled water is in use, outdoor water budgets are calculated similarly to residential outdoor water budgets, but with a higher plant factor to account for areas with more turf. The same calculation applies to water budgets for potable water and public spaces.

 Irrigation Customers: 

Recycled Water Customers: 

Public Spaces Irrigation Customers: 


Customers whose water use remains within their water budgets are billed at the lowest available rates, and customers who exceed their water budgets are billed at higher rates for the amount of water they use above their water budget. All water rate revenue in excess of the cost of imported water will be designated for the Water Efficiency Fund to fund new water supply projects and invest in water efficiency improvements to maintain reliability.

To most effectively manage water resources, the Water Efficiency Fund was created to help promote water conservation, invest in new sources of water supply and develop water use efficiency programs. The program implements rebates for water efficient fixtures and appliances, water conservation educational campaigns, and more, to promote drought-friendly practices within the local community. The Water Efficiency Fund receives most of its funding through the “non‐budget tiers” (currently Tiers 3, 4, and 5 for residential customers and Tiers 2, 3, and 4 for non-residential customers) of water and recycled water rate revenue. The greater the demand for water, the greater the need to expand the Water Supplies, Conservation and Water Use Efficiency Programs and incur related costs. These incremental cost increases are therefore proportionately allocated to customers who use water within Tiers 3, 4, and 5.

We’re committed to ensuring that our customers have a customized water budget that promotes efficiency while providing the water necessary to meet their everyday needs. Should legitimate reasonable need for additional water arise for your home or business, our Water Budget Based Rate Structure includes simple steps to modify your water budget. Simply fill out a Water Budget Modification Request, either residential or commercial based on your needs, or call the District to provide us with some basic information and we will guide you through the process.

For more information about your water budget, please contact the Moulton Niguel Water Efficiency Department at (949) 448-4025.