Prop 218 Notices

Prop 218 Notices

The Irvine Ranch Water District is a public agency that provides water and sewer service. Rates are based on the actual cost to provide these services and are set each year during the annual budget process. The annual budget is adopted by the Board of Directors and goes into effect on July 1. A critical IRWD business objective is to keep costs, and therefore rates, as low as possible for our customers. When compared with other agencies providing similar services in Orange County, IRWD’s rates are consistently among the lowest.

Proposed Rate Changes for FY 2017-18

For specific details on proposed rate changes that apply to you, please read the Proposition 218 notice that was mailed to your home or business. You can also select from the links below. A copy of the FY 2017-18 Operating Budget is available here.

FY 2017-18 Proposition 218 Notices

Please select from the following links to learn about the rate changes that apply to you.

Irvine Rate Area
Los Alisos Rate Area*

IRWD Irvine Residential Customers
IRWD Irvine Commercial Customers
IRWD Irvine Landscape Customers
IRWD Irvine Newport North Customers

IRWD Los Alisos Residential Customers
IRWD Los Alisos Commercial Customers
IRWD Los Alisos Landscape Customers

The Los Alisos Rate Area will Transition to the IRWD Rate Area  on July 1, 2017*

Effective July 1, there will no longer be a Los Alisos Rate area. There will only be one rate area for ALL IRWD customers. The Proposition 218 notice reflects this transition.  Please see the Los Alisos Rate area notice in the above chart.


Water Budget and Bill Calculator for FY 2017-18 Rates

The Water Budget and Bill Calculator can be used to estimate your FY 2017-18 water budget and estimated bill for any month of the year. Please note the calculator is only an estimate and may not reflect other factors which could affect your monthly bill, such as variances, credits or other adjustments. If you have any questions about the calculator or your bill, please contact customer service at or 949-453-5300.


Understanding the IRWD Budget Based Rate Structure

Since 1991, the District has utilized a budget based rate structure to encourage conservation and water use efficiency. As customers use more water relative to their monthly water budgets, usage gets billed at increasingly higher rates based upon the increased costs of supplying the additional water supplies. Customers who stay within their monthly water budgets pay lower rates, while inefficient and wasteful users pay the added costs that IRWD incurs to purchase more expensive imported water, to operate its water supply reliability programs and to invest in the additional resources needed to help customers in the Inefficient and Wasteful tiers conserve water. FY 2017-2018 rates reflect the actual costs associated with supplying water for each tier as required under California State law, Proposition 218. This is referred to as the “cost of service” for each tier.

Why Rates are Proposed to Change

Uncontrollable costs of service are the major factors why rates have increased including: 1) Increases in pass-through costs from the Orange County Water District (11%) for pumping groundwater (our lowest cost of source water) and 2) Increases from the Municipal Water District of Orange County (4%) in pass through charges from the Metropolitan Water District of Southern California for imported water (the most expensive source of water) purchased through the regional water wholesaler, the Municipal Water District of Orange County.

How are the Costs of Water Assigned to Rate Tiers?

Each rate tier is assigned a rate based on the actual cost of service for the water.  Each source has a different cost of water. Local ground water from the Dyer Road Wellfield is the District's lowest cost of water - while imported water is the District's highest cost of water. The Low Volume rate tier rewards customers who use the least amount of water, which reduces the need for IRWD to purchase more expensive water supplies.  The Base rate tier is for customers that stay within their monthly water budget allocation.  The Ineffecient and Wasteful tiers are for customer who exceed their monthly budget.  The chart below shows how costs for different sources of water are assigned to each rate tier based on the actual cost of service.

Water Source Low Volume Tier Base Tier Inefficient Tier Wasteful Tier
  Lowest Cost of Water Melded Cost of Water Blended Cost of Baker & Potable Imported Water Loaded Cost of Imported Water
Dyer Road Well Field 100% 32%
Deep Aquifer Treatment System 23%
Irvine Desalter Project 17%
Wells 21 & 22 7%
Orange Park Acres and Lake Forest Wells 3%
Baker Water Treatment Plant 18% 61%
Imported Water from Metropolitan Water District( MWD) 39% 100%
Costs of Service Low Volume Tier Base Tier Inefficient Tier Wasteful Tier
Total Water Source Cost $1.32 $1.66 $2.95 $3.40
District Wide Conservation $0.04 $0.04 $0.04 $0.04
Conservation Targeted to Over Budget Customers and Natural Treatment System Costs $1.10 $8.62
Total Cost Per Tier Proposed FY 2017-18 $1.36 $1.70 $4.09 $12.06
FY 2016-17 Rates by Tier $1.21 $1.65 $4.01 $12.01
Change $0.15 $0.05 $0.08 $0.05
* Why are Rates in the Low Volume Tier Increasing More than Other Tiers

While local groundwater pumped by IRWD continues to be our lowest cost water, the OCWD has increased associated fees (11%) for pumping this water.  Because Low Volume customers get our lowest cost water, the 11% increase has the greatest impact on Low Volume customers.

Updates to Budget Based Rate Structure and Rates

The following sections provide updated information on FY 2017-18 indoor and outdoor water budgets, billing tiers, fixed service charges, pumping surcharges and other technical data. For additional details, please view your Prop 218 Notice.

 Click on the sections below for additional information.

Sample Bills for Residential Customers

  fy17 18 bill compare       

Download Sample Bill Comparison Chart Here 

Note: Sample bills do not include any potential pumping surcharge amounts


Indoor Water Budgets Are Unchanged

The indoor water budget for all customers remains unchanged at 50 gallons per resident per day.


Outdoor Water (Potable) Budgets Have Not Changed

Your outdoor monthly water budget is based on 60% warm season turf and 40% drought tolerant landscaping.

Your outdoor water budget is not based on 100% drought tolerant landscaping.

Those customers with lawns may be over their monthly outdoor water budget.

Customers who continue to irrigate non-turf landscape with sprinklers and over-head spray may go over their monthly budget because these systems are less efficient at delivering water to the plants.

Drip irrigation is the most efficient form of irrigation for non-turf areas.

Outdoor Landscape Drinking (Potable) & Recycled Water Monthly Budget


Monthly Budget Basis

Irrigated with Potable Water

60% warm-season turf + 40% drought tolerant landscape

Irrigated with Recycled Water

100% warm-season turf

Average Monthly Residential Water Budget for a 30-Day Bills Period

Residence Type

Indoor ccf

Average Outdoor ccf

Total Average Monthly Budget ccf

Attached Home Condo








Single Family Residence





Fixed Water Service Charges Have Not Changed

There are no changes to the monthly fixed water service charges.

The fixed charge is based on the meter size which appears on the bill.

The water service charge is a fixed charge based on a 30-day billing cycle. Billing cycles that are longer or shorter than 30 days will produce service charges that are proportionally larger or smaller. See below for examples for a customer with a $10.30 monthly fixed water service charge:


  • 30-day billing cycle produces $10.30 water service charge
  • 34-day billing cycle produces $11.67 water service charge
  • 26-day billing cycle produces $8.93 water service charge


Water Conservation (Leaseback) Credit

A water conservation, or “leaseback” credit recognizes low volume users that don’t fully use their reserved flow capacity. IRWD will provide the credit to users who are underutilizing that flow and effectively “leasing back” to the system for other users. This prevents the District from having to upsize infrastructure as quickly as capacity is exhausted.

Note: The leaseback credit is noted as "Water Conservation Credit” on the monthly bill.

Customers that remain in the Tier 1 – “Low Volume” tier for 9 out of 12 months for the previous calendar year will receive a $2.00 monthly credit during the following year.

This credit is also based on a 30-day billing period and will be adjusted up or down depending on the actual length of the billing cycle. See below for examples:


  • 30-day billing cycle produces $2.00 credit
  • 34-day billing cycle produces $2.26 credit
  • 26-day billing cycle produces $1.73 credit
  • Note: New customers must be with the District for a full calendar year before they can receive the credit.


Fixed Sewer Service Charges Have Not Changed

There are no changes to the monthly fixed sewer service charges.

There are three tiers of sewer service charges which are based on the three months with the lowest potable water usage from the previous calendar year.

Note: New customers will be billed at the highest tier service charge until the customer has established a full calendar year of water usage history.

The sewer service charge is a fixed charge based on a 30-day billing cycle. Billing cycles that are longer or shorter than 30 days will produce service charges that are proportionally larger or smaller. See below for examples of a customer with a $25.75 monthly fixed sewer service charge:


  • 30-day billing cycle produces $25.75 sewer service charge
  • 34-day billing cycle produces $29.18 sewer service charge
  • 26-day billing cycle produces $22.32 sewer service charge


Pumping Surcharges Have Decreased (Maps Here)

IRWD incurs additional pumping costs in order to provide service to customers who reside at higher elevations.

The pumping surcharge is based on actual prevailing energy costs and varies depending upon the elevation of the area served. If a customer lives in an area affected by a pumping surcharge, it will be itemized on the monthly bill.

PDF maps of the potable and recycled water pumping zones are availabe below.


Proposed Pumping Zones





Zone 1

$ 0.21

$ 0.21

Zone 2

$ 0.35

$ 0.35

Zone 3

$ 0.65

$ 0.64



Zone A

$ 0.22

$ 0.21

Zone B

$ 0.36

$ 0.34

Zone C

$ 0.49

$ 0.47



There Are Still Four Billing Tiers

Billing tiers are based on cost of service and on proportional use.

The number of billing tiers remains unchanged at four, as follows:


  • Tier 1 – Low Volume
  • Tier 2 – Base Rate
  • Tier 3 – Inefficient
  • Tier 4 - Wasteful


Billing Tier Percentages Have Changed Slightly

The billing tiers are based on cost of service and on proportional use.

The number of billing tiers remains the same.

The percentage of your monthly water budget allowed within each tier has changed for all customer types except condominiums

Residential multi-family homes with no outdoor water use will continue to have a lower percentage of monthly water budget formula than residential homes that have outdoor water use. Most Multi-Family residents can only reduce water use indoors; usage over the monthly budget is most likely a leak.


Rate Tier Proposed Changes

Low Volume Tier

Proposed Low Volume

Base Tier

Proposed Base Rate


Proposed Inefficient


Proposed Wasteful

By Customer Type









Single Family Home

0 – 40%

No Change

41 – 100%

No Change

101 - 130%

101 - 140%




0 – 40%

No Change

41 – 100%

No Change

101 -130%

No Change


No Change


0 – 60%

0 – 50%

61 – 100%

51 – 100%

101 - 120%

No Change


No Change

Potable   Landscape

0 – 60%

0 – 40%

61 – 100%

41 – 100%

101 - 160%

No Change


No Change

Recycled Landscape

0 – 40%

No Change

41 – 100%

No Change

101 - 130%

101 - 140%





Efficiency Factor for Functional Turf and Recycled Water Budgets Has Not Changed

The water budget for recycled water use and for functional turf irrigated with drinking (potable) water, such as a sport field will be based on 75% irrigation efficiency. This results in a landscape factor of 0.87.


IRWD Rate Increase History

The rate increase proposed for FY 2017-18 is the lowest since FY 2010-11


Technical Formula for Monthly Water Budgets (All customer types)

Technical Formula for the Monthly Water Budget
Account Type Number of Residents
Landscape Area (Default) Indoor Budget
50 gallons per personper day
Water Budget*LA x ET x LF
Total Monthly
Water Budget
Attached Home Condo 3 435 sq. feet # Residents x 50 gpd x days in bill period LA x ET x LF (0.75) Indoor + Outdoor
Apartment 2 N/A # Residents x 50 gpd x days in bill period N/A Indoor
Single Family Residence 4 1,300 sq. feet # Residents x 50 gpd x days in bill period LA x ET x LF (0.75) Indoor + Outdoor
Irrigation Potable N/A Site specific based on irrigated acreage N/A LA x ET x LF (0.75) Outdoor
Irrigation Recycled N/A Site specific based on irrigated acreage N/A LA x ET x LF (0.87) Outdoor
Functional Turf irrigated with Potable Water N/A Site specific based on irrigated acreage N/A LA x ET x LF (0.87) Outdoor
Commercial, Industrial Institutional N/A N/A Site specific Site specific, based on irrigation needs Site Specific
*the outdoor water budget is multiplied by 36.3 to convert to ccf


gpd Gallons per day
ccf 100 cubic feet. 1 ccf = 1 billing unit or 748 gallons
LA Irrigated landscape acreage of the specific property (acres)
ET - evapotranspiration Reference evapotranspiration: The amount of water that evaporates into the air and the amount of water that is transpired through the vegetation. Evapotranspiration values are computed daily from IRWD’s three weather stations for the bill period. This data is provided from IRWD weather stations located in the coastal, central or foothill zones.
Landscape Factor
The landscape factor measures the specific amount of irrigation water needed for the plants in your yard. The rate structure is based on the assumption that your landscaped area is 60% grass and 40% drought tolerant plants, which combine for a landscape factor of 0.75.For recycled water and functional turf irrigated with potable water, the landscape factor is 0.87, based on 100% warm season turf.
Indoor Use Based on the number of people per household for residential accounts. Based on the number of employees and business process water for commercial/industrial accounts
N/A Not applicable


State of California Ends Drought Emergency

On April 7, 2017, Governor Brown ended the drought State of Emergency in most of California, including Orange County.  However, the prohibitions on wasteful water use practices are still in effect including:

·       Hosing off sidewalks, driveways and other hardscapes;

·       Washing automobiles with hoses not equipped with a shut-off nozzle;

·       Using non-recirculated water in a fountain or other decorative water feature;

·       Watering lawns in a manner that causes runoff, or within 48 hours after measurable precipitation; and

·       Irrigation ornamental turf on public streets and medians








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