Urban Water Use Efficiency

Water that is not used for agriculture or to support the environment is referred to as “urban water.”


Urban water includes water that is used for:


  • Drinking
  • Toilets and showers
  • Landscaping
  • Car washing
  • Businesses
  • Industrial processes


Climate change, population growth, land development, and increasing regulations on water use impact our water supply, which means that we must be more diligent in conserving the water we have now, so that we have sufficient supply for the future.  


Water waste costs everyone. Waste leads to higher water prices, and developing new water supply solutions such as building more reservoirs, water recycling, and desalination, are all expensive options.  


To help ensure that we use our urban water supplies wisely, the Urban Water Use Efficiency program provides information and assistance to water suppliers, agencies, and the public in several areas:


  • Urban water management planning and other water supplier management and reporting requirements
  • Leak detection information and resources to reduce water waste
  • Understanding and implementing the Model Water Efficient Landscape Ordinance (MWELO)
  • Commercial, Institutional, and Industrial water efficient practices
  • Tips on what individuals can to do save water

About half of the urban water is used for landscape irrigation in California. Large water savings can be gained by proper landscape design, installation, and maintenance. New development and retrofitted landscape water efficiency standards are governed by the Model Water Efficient Landscape Ordinance (MWELO). All agencies must adopt, implement, and enforce the MWELO or a more stringent ordinance.


In 2015, Executive Order B-29-15  tasked DWR with revising the 2010 updated MWELO to increase water efficiency standards for new and retrofitted landscapes through encouraging the use of more efficient irrigation systems, greywater usage, and onsite storm water capture, and by limiting the portion of landscapes that can be covered in turf. Updating the ordinance to incorporate these elements will help stretch our limited water supplies. The EO also required that agencies report on their implementation and enforcement of local ordinances by December 31, 2015.  DWR’s Water Use and Efficiency branch worked with several affected agencies, interested groups, and the public to prepare the current (2015) updated MWELO to improve landscape irrigation water savings in accordance with the EO.   

For Implementation Agencies Reports, previous submittals, and archived public process records, please contact WELO@water.ca.gov


For more information and public process records or to be placed on a list of interested parties, please contact Todd Thompson (Todd.Thompson@water.ca.gov).


The Legislature adopted Senate Bill 555 (SB 555) in October 2015 because it found that water conservation on the supply side of the state’s larger urban retail water suppliers (urban water suppliers) may be improved by performing validated water loss audits on their water systems. Accordingly, SB 555 added Section 10608.34 to the California Water Code, requiring DWR to establish rules for conducting and validating water loss audits, technical qualifications for persons performing water loss audit validation, and reporting requirements for submitting validated water loss audits to the Department.


Water loss audits are now a permanent requirement. SB 555 requires all urban retail water suppliers in the state to submit a completed and validated water loss audit annually to the DWR beginning October 2017.  Previously, Senate Bill 1420 established that urban water suppliers submit a report that quantifies water system losses with their urban water management plans.  As a result of the previous legislation, the department established validated water loss audit requirements for the submittal of annual validated water loss audits. On October 18, 2017, the California Water Commission approved the Regulations for Validated Water Loss Audit Reporting. The approved regulations will not be final until they are also approved by the California Office of Administrative Law (OAL).

+Water Loss Audit Submissions

The water loss audit reports submitted to DWR, as required by Senate Bill 555, are now posted online. Although DWR has posted the water loss audit reports, DWR has not reviewed the reports and will not review until the time when the regulations are approved by OAL. Please read further before continuing to view the water loss audits.

Water loss audits evaluate real and apparent water losses occurring in a potable water distribution system. Estimating the scale and cost of these losses allows utilities to identify opportunities for saving water and recovering revenue. For the first time in California, water loss audit submissions were reviewed by validators to guarantee consistency. The scope of this review followed the validation methodology detailed in Water Research Foundation project 4639: Level 1 Water Audit Validation. Level 1 water audit validation aims to:

  1. Identify and, where possible, correct inaccuracies in water audit data and application of methodology
  2. Evaluate and communicate the uncertainty inherent in water audit data

A Level 1 validation does not guarantee accurate estimations of losses. Level 1 water audit validation is conducted through review of the summary data supporting a water audit and an interview with staff about water audit data and operational procedures. As a result, a Level 1 validation improves audit reliability but does not diagnose and correct errors buried in raw data or resulting from instrument inaccuracy, both of which require deeper investigation (Level 2 or Level 3 validations respectively) to unearth.

The water loss audit database is available here

Technical Assistance

The Water Audit is an accounting procedure using agency data to identify water losses that may be due to distribution system leaks. The Water Audit requires the agency to gather an assortment of data for a defined audit period. The Water Conservation Guidebook No. 5: Water Loss and Leak Detection  lists the type of data necessary and provides worksheets as guidelines or for use in the audit.

Once an agency has determined the percentage of water loss and has performed a benefit-cost analysis to verify economic feasibility, a Leak Detection program may be established. The leak detection program is the field portion of the program. It requires knowledge of the layout of the distribution system and a good ear when using the sonic equipment for finding areas with leaks.  The Guidebook provides information on what steps are required to establish and perform a leak detection program.

A simple Microsoft Excel Workbook, Water Audit Workbook (v2.0 2000), was developed by DWR and is available upon request. However, Water Code Section 10631(e)(2)(B) refers to the use of the AWWA System Water Audit Software.

DWR’s Regional Offices have leak detection equipment available for short-term loan to a water agency and they will provide assistance to local water agencies seeking to conduct a water audit and leak detection survey of their distribution system.

Northern Region Office:                Mark Rivera        530-529-7301                    mark.rivera@water.ca.gov

North Central Region Office:        James Briggs       916-376-9628                    james.briggs@water.ca.gov

South Central Region Office:        Steve Ewert        559-230-3334                    steve.ewert@water.ca.gov

Southern Region Office:                Sergio Fierro       818-500-1645 x246         sergio.fierro@water.ca.gov 


For more information about the water audit and the distinct forms of water loss, please refer to American Water Works Association manual M36: Water Audits and Loss Control Programs.

Data and Transparency

As of June 9, 2017, the following UWMPs have been submitted to DWR:

394 Urban Water Suppliers
12 Suppliers voluntary (not required)

6 Regional Alliances

Submitted documents and data may be viewed on the WUE Data Portal.

Publications & Reports

Related Pages

Contact Information

What's New!

SB 555 added Section 10608.34 to the California Water Code, requiring DWR to establish rules for conducting and validating water loss audits, technical qualifications for persons performing water loss audit validation, and reporting requirements for submitting validated water loss audits to the Department.