Bill Calculator
Use our bill calculator and learn how Moulton Niguel maintains the lowest average bill in South Orange County!
Maintaining the Lowest Average Bill in South Orange County
Moulton Niguel Water District continues to deliver the lowest average combined water and wastewater bill in South Orange County. We constantly strive to control costs and make prudent investments to provide the highest level of service and value to our customers.
Effective January 1, 2026 Moulton Niguel’s bills began to reflect updated water, recycled water, and wastewater rates that were approved by our Board of Directors in December 2025.
Key Rate Drivers:
- $605 MILLION CAPITAL INFRASTRUCTURE PLAN: Over the next decade, Moulton Niguel will invest more than $605 million in infrastructure improvements to support reliable water service, maintain wastewater treatment and regulatory compliance, and enhance local fire protection services.
- RISING IMPORTED WATER COSTS: Moulton Niguel imports all of our drinking water from Northern California and the Colorado River through the Metropolitan Water District of Southern California. In 2024, Metropolitan approved substantial increases to its wholesale water rates and forecasts additional increases for its imported water costs. These higher costs impact our customers and 19 million people throughout Southern California.
- INVESTMENTS IN DIVERSIFIED WATER PORTFOLIO: Moulton Niguel is building a resilient water portfolio that is diversified across regions. We are investing in the next generation of water reuse technology to prepare for ongoing water supply uncertainties.
Bill Calculator Tool
Click here for Moulton Niguel’s Water Budget Bill Calculator
You can use the bill calculator to see how changes in your water usage may affect your bill. For more information on our water budget based rate structure,
visit staging-mnwdnewtheme.kinsta.cloud/waterbudgetbasedrates
To determine the Evapotranspiration amount for your microzone, refer to your bill statement or go to our water saving tools page and use the Evapotranspiration Map.
Questions?
Every month, each customer receives a calculated “water budget” that represents an efficient volume of water that meets his or her individualized water needs. There are five customer classes:
- Single-Family Residential
- Multi-Family Residential
- Commercial
- Irrigation
- Recycled Water Customers
Single-family and Multi-family Residential Customers
Total Household water budget = Indoor water budget + Outdoor water budget
All water used by a single-family or multi-family residential customer within their calculated
indoor water budget is billed at the Tier 1 rate and the outdoor water budget is billed at the
Tier 2 rate.
Indoor Water Budget is based on these factors:
Household Size: The number of people living in your household.
Number of Days in Billing Cycle (Days Billed): The number of days you are being billed for service. This information can be found on your water bill and comes from the meter
read dates.
Base Water Allocation (GPCD): Gallons per capita per day. Every residential customer receives a base water budget of 55 gallons per capita per day
Outdoor Water Budget is based on these factors:
Irrigable Area: The outdoor square footage of your property requiring water. Pools and spas are also included in the irrigable area. A Geographic Information System or on-site survey data was used to determine your irrigable area.
Landscaping Factor: A factor applied to account for plant water requirements and irrigation efficiencies. Your bill uses a landscaping factor based on the type of water applied: 0.7 for single-family and multi-family residential, 0.7 for potable irrigation,
0.8 for recycled water, and 1.0 for public spaces irrigation.
Evapotranspiration (ET): The amount of water that is lost each day due to evaporation and plant transpiration. Evaporation will vary due to factors such as wind, humidity and temperature. Transpiration is the amount of water that plants lose from their leaves and
plant tissue. The ET rate is measured every day in inches. For your water budget, the ET for each day in the billing cycle is added up. Moulton Niguel measures ET using weather stations that can calculate precise data for 110 distinct microclimate zones within our
service area. Visit https://gram.mnwd.com/etmap/ to see your ET rate.
Public Spaces Irrigation Customers:
Total water budget = Irrigable area (square footage per parcel) x Evapotranspiration x 1.0 Landscaping Factor x 0.62 / 748 (conversion factor to calculate budget in HCF). All water used by a public spaces irrigation customer within his or her calculated outdoor water budget is billed at the Tier 1 rate.
Recycled Water Customers:
Total water budget = Irrigable area (square footage per parcel) x Evapotranspiration x 0.8 Landscaping Factor x 0.62 / 748 (conversion factor to calculate budget in HCF). All water used by a recycled water customer within his or her calculated outdoor water budget is billed at the Tier 1 rate.
Potable Irrigation Customers:
Total water budget = Irrigable area (square footage per parcel) x Evapotranspiration x 0.7 Landscaping Factor x 0.62 / 748 (conversion factor to calculate budget in HCF). All water used by an irrigation customer within his or her calculated outdoor water budget is billed at the Tier 1 rate.
Commercial Customers:
For commercial customers, your water budget is based on a rolling average of the current month and the same month in the prior two years. Each month’s usage is weighted by the number of days in that bill to account for the potential difference in meter read dates for the different years. Water budgets for commercial customers shall be calculated such that a minimum budget of one billing unit shall be provided. For commercial customers with less than 3-years of data, the water budgets are calculated as follows: (a) for the first year, the customer’s budget is equal to water used; and (b) for the 2nd year, it is an average of current and the previous year’s usage in that month (e.g. February 2021 and February 2022) weighted by the number of days in each bill period.
You can use the bill calculator app to see how changes in your water usage may affect your monthly bill. For more details of the approved changes and annual rate schedules, please see our 2021 Notice of Public Hearing.
Your wastewater bill is comprised of two components:
- A fixed monthly service charge representing the share of the District’s fixed costs associated with providing ongoing wastewater service to your property.
- A per-person charge representing the share of variable costs associated with providing wastewater service to a household of your size to accurately capture the wastewater treatment cost increases.
Your water bill is comprised of two components:
- A fixed monthly service charge that is designed to recover a significant portion of the District’s fixed costs (e.g. facility repairs and maintenance, meter reading, billing, customer service costs) based on the size of the water meter serving your property.
- A variable volumetric water consumption charge, which is based on the number of units of water you use (one unit of water is equal to one hundred cubic feet (HCF), or 748 gallons). Each billing unit of water you use is grouped into a tier based on your individualized water budget, with higher rates assessed for usage in excess of your budget.