Understanding EBMUD's Wastewater Rates

EBMUD Wastewater – Protecting Public Health and the San Francisco Bay

Since 1951, EBMUD has helped protect public health and water quality in the San Francisco Bay by providing wastewater treatment. Today, EBMUD’s wastewater system serves an area of 88 square miles and a population of 740,000. The wastewater system consists of 37 miles of sewer interceptors, 15 pumping plants, 3 wet weather facilities, and the main wastewater treatment plant at the base of the Bay Bridge.

Sewage from Alameda, Albany, Berkeley, El Cerrito, Emeryville, Kensington, Oakland, Piedmont, and part of Richmond flows through city and locally-owned collection systems and into the EBMUD sewer interceptors leading to the main wastewater treatment plant. There the sewage is treated, meeting stringent state and federal standards, before the water is recycled or released into the San Francisco Bay. During severe storm events, the wet weather facilities provide additional pumping and pipeline capacity, storage, and treatment to manage excess water that enters the sewer system.

EBMUD also operates a Pollution Prevention Program as required by the Regional Water Quality Control Board and United States Environmental Protection Agency. Through the Pollution Prevention Program, EBMUD develops and implements strategies to monitor and minimize pollutants from residential and non-residential sources.

Protecting public health and the environment by collecting and treating wastewater 24 hours a day, year-round, requires substantial investment in major infrastructure, chemicals, equipment maintenance, and around-the-clock staff to operate the facilities.

Wastewater Rates Overview

EBMUD is a public, not-for-profit agency. Part of our mission is to provide fair and reasonable rates for EBMUD customers. Rates are set to recover the cost of providing service. EBMUD rates are in full compliance with the law, including Proposition 218 requirements for notices and public hearings on proposed rate increases (Proposition 218 notice available on the Budget and Rates page). EBMUD’s rates and related analysis are also evaluated through a cost-of-service study, conducted by an independent, outside firm.

Almost 80 percent of EBMUD’s wastewater revenues come directly from customers via wastewater rates and charges. The remaining 20 percent of revenue comes from fees collected from trucked waste, property taxes, reimbursements from other agencies and other revenue sources. There are three categories of EBMUD wastewater rates and charges: wastewater treatment charges and pollution prevention fees, which are both collected on the EBMUD bill, and the wet weather facilities charge collected on the property tax bill. Of the revenue collected from wastewater rates and charges, about 73 percent comes from wastewater treatment charges, 1 percent from pollution prevention fees, and 26 percent from the wet weather facilities charge.

Wastewater Treatment Charge

There are three charges that make up the wastewater treatment charge collected on the EBMUD bill: the service, flow, and strength charges.

  • The service charge is a fixed monthly charge per service connection and is calculated to recover a portion of EBMUD’s fixed costs of providing wastewater services.
  • The flow charge is a variable monthly charge based on a customer’s metered water use and assumptions about how much water is returned to the sewer system to be treated at the EBMUD wastewater treatment facilities. The flow charge recovers a portion of EBMUD’s costs of conveying and treating wastewater and is based on the volume of water discharged.
  • The strength charge is based on the estimated concentration of waste contaminants that a customer discharges into the sewer system and is calculated to recover EBMUD’s costs of treating these contaminants.

San Francisco Bay Pollution Prevention Fee

The San Francisco Bay Pollution Prevention Fee is a fixed monthly charge collected on the EBMUD bill for residential and non-residential customers based on the costs of EBMUD’s pollution prevention programs for residential and non-residential customers including the Main Wastewater Treatment Plant tour program and a pharmaceuticals disposal program. EBMUD’s pollution prevention programs were established to reduce pollutants at the source and protect San Francisco Bay through education, public outreach, and permit requirements for commercial businesses.

Wet Weather Facilities Charge

The Wet Weather Facilities Charge is a fixed annual charge collected on the property tax bill assessed by lot size for properties connected to the wastewater system. It is calculated based on EBMUD’s costs for the wet weather program mandated by the U.S. Environmental Protection Agency to improve EBMUD’s ability to collect and treat increased wastewater flows during rainy weather.

Sewer Collection Charge Administered by Local Cities and Sanitary Districts

While EBMUD provides the treatment of wastewater at the Main Wastewater Treatment Plant and wet weather facilities, the cities and sanitary districts are responsible for the local sewers that collect wastewater from customers’ sewer lines. Local sewer collections systems are owned and operated by cities and sanitary districts in our service area. To recover the costs for these systems, the cities and sanitary districts impose sewer service charges. EBMUD does not set or receive these sewer service charges. In some cities, for efficiency, EBMUD collects these local sewer service charges on the EBMUD water and wastewater bill on behalf of those cities and sanitary districts.

The Building Blocks for the Wastewater Rates and Charges - Flow, Strength and Inflow/Infiltration

The EBMUD wastewater facilities are designed, constructed, and operated to address three primary wastewater components: flow, strength, and inflow and infiltration.

Wastewater Flow and Strength

Wastewater flow is the volume of wastewater discharged into the sewer system from customers’ sanitary sewer connections. Wastewater strength is a measure of contaminants in the wastewater discharge that are removed by the treatment process. EBMUD uses two indicators to determine the strength of a wastewater discharge: Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS). COD is a measure of the amount of organic matter in  wastewater discharge expressed in milligrams per liter. While the level of COD from residential customers is relatively homogenous, the COD can vary significantly among non-residential customers depending on the type of business. For example, a wastewater discharge from a food processing plant will have much higher COD than an office building. Another strength contaminant from customers’ wastewater discharges is suspended solids, measured in milligrams of TSS per liter. TSS measures waterborne particles that are greater than two microns in size, which are primarily inorganic materials. “Stronger” wastewater costs more to treat, and EBMUD’s strength charges are designed to recover those extra costs from customers who tend to generate stronger wastewater.

Inflow and Infiltration

The other major component in wastewater is the groundwater and stormwater that enters the wastewater system through cracks and leaks in local city sewers and private sewer laterals. During storms, this inflow and infiltration can increase the flows to the wastewater treatment plant to more than 10 times the dry weather flow.  EBMUD uses special infrastructure to move, store, and treat these peak wet-weather flows which would otherwise overwhelm the system and result in discharges of untreated or partially treated sewage into San Francisco Bay. The Wet Weather Facilities Charge is EBMUD’s primary source of revenue to pay the cost of those facilities and continue our work to protect the Bay.

Wastewater Rates and Charges are Based on a Cost-of-Service Study

EBMUD’s wastewater facilities and processes address the three primary components of wastewater - flow, strength, and inflow and infiltration. EBMUD contracts with an independent, outside firm to conduct a cost-of-service study to look at each EBMUD wastewater facility and process to analyze how much of the costs are used to treat the three components. This analysis helps us to establish fair wastewater rates and charges. This approach is consistent with the Water Environment Federation Manual of Practice No. 27, Financing and Charges for Wastewater Systems and with best practices used by wastewater agencies throughout the state (see Water and Wastewater Pricing for a US EPA overview of water and wastewater pricing). EBMUD’s current COS study shows that approximately 24 percent of the wastewater system costs are attributed to flow, 38 percent of costs are attributed to strength, and 38 percent of costs are attributed to inflow and infiltration.  

Wastewater Treatment Charge Cost of Service

To equitably recover our costs from the customers who generate wastewater discharges, the cost-of-service study analyzes contributions to the flow, strength, and inflow and infiltration  components from single-family residential, multi-family residential, and non-residential customer classes. For example, EBMUD uses each customer’s metered water use to determine the volume of wastewater flow the customer discharges into the sewer system. EBMUD then charges the customer a wastewater flow charge commensurate with the measured water use. Because some of the metered water use for residential customers is used for irrigation and not discharged into the sewer system, the flow charge for single family and multi-family residential customers is capped at 900 cubic feet per month (about 220 gallons per day) as an assumed maximum indoor water use volume. Water use above 900 cubic feet per month is assumed to be used for irrigation and is not assessed a wastewater charge.

The charges for the wastewater strength components of COD and TSS for each customer class are determined by a combination of sampling and testing of customer discharges and analysis of strength assumptions used in other studies and reports. As the discharge of wastewater strength is fairly homogeneous for each single or multi-family residential household, residential customer accounts pay a fixed strength charge based on the number of dwelling units served by that account and meter. For example, if the residential customer is a duplex, the account would be assigned two dwelling units and assessed a charge equal to two times the dwelling unit fixed strength charge. For non-residential customers, the amount of wastewater strength discharged varies significantly with the amount of flow and the characteristics of the wastewater discharge, so the strength charge is assessed based on two factors: (1) metered water use, and (2) strength assumptions for the type of business operated. For wastewater customers with unique strength characteristics, or for customers who have wastewater discharges that require special testing and monitoring for pollutants, high flow and/or high strength wastewater, EBMUD issues a discharge permit that may include unique strength assumptions and treatment rates for the permit holder along with conditions of discharge.

Wet Weather Facilities Charge Cost of Service

During large storms, when flows coming in exceed the capacity of the main wastewater treatment plant, EBMUD manages the high flows by operating three wet weather facilities constructed for the sole purpose of treating high flows during large storm events. The cost for providing this expanded capacity and facilities is recovered through the wet weather facilities charge, which is collected on each parcel connected to the local sewer collection systems. The amount of inflow and infiltration that enters the wastewater system during storms is generally proportional to the miles of sewer pipe that serves the community. For example, a large sewer collection system with more miles of sewer pipe will likely have more inflow and infiltration than a smaller collection system. The volume of inflow and infiltration is unrelated to the monthly water or wastewater usage of the wastewater customers.

The structure of the wet weather facilities charge is based on the rationale that larger parcels contribute proportionally more to wet weather flows than smaller parcels because larger  parcels generally require more linear feet of pipe in the collection system than smaller parcels, resulting in more opportunity for groundwater and storm water to enter through defects in the wastewater collection system. For these reasons, EBMUD uses parcel size rather than customer monthly water or wastewater use as the basis for this charge. The wet weather facilities charge is structured into three categories of parcel sizes:

  • 0 to 5,000 square feet
  • 5,001 to 10,000 square feet
  • greater than 10,000 square feet

The charge is collected on the property tax bill for all parcels with connections to the local sewer collection systems in EBMUD’s wastewater service area. The charge for public agencies that are exempt from property taxes is collected through the EBMUD’s billing process.

Rate-setting Process

EBMUD adopts new wastewater rates and charges governed by Proposition 218 on a two-year cycle, with new rates and charges taking effect at the start of EBMUD’s fiscal year on July 1. When developing the proposed rate changes, EBMUD holds a series of Board rate and budget workshops that are open to the public and noticed in advance on the EBMUD website and on social media. These workshops typically begin in January and end in May before the formal public hearing in June. EBMUD has also held regular media briefings and at least one evening public meeting in recent years. The public is encouraged to attend and provide comments at these Board workshops and public meetings. When significant changes to rates are being considered, the cost of service study generally needs to be updated, and EBMUD may hold additional Board workshops which are also open to the public and noticed in advance. Members of the public interested in EBMUD’s wastewater rates can check the Board agenda and materials posted on the EBMUD website to monitor Board discussion of proposed wastewater rates (see Board meetings).

Before adopting proposed changes to the charges collected on the EBMUD bill and property tax bill, the EBMUD Board holds a public hearing, typically in June, to hear all oral comments and consider all formal written protests to the proposed rate changes. For wastewater charges governed by Proposition 218, a notice of the public hearing and proposed rate changes is sent in advance of the public hearing to all parcel owners and tenants who are directly responsible for payment of the wastewater charges. If written protests against the proposed rate changes are not presented by the majority of property owners (or tenants directly responsible for the charges), the EBMUD Board is authorized to adopt the rate changes (Proposition 218 notice available on Budget and Rates page).

Update - January 2022