Water Loss Standard

Published: July 22, 2021

The Basics

  • The water loss standard is derived from separate but related legislation, Senate Bill 55 (2015), which also requires urban water retail suppliers to submit annual validated water audit.  Supplier annual validated water audits can be found here on DWR’s website.
  • The water loss standard focuses on real losses expressed in gallons per connection per day or gallons per mile (of pipe) per day depending on system size.  The vast majority of suppliers will have a standard in gallons per connection per day.
  • Supplier specific 2028 water loss targets (maximum loss) are calculated from a State Water Resource Control Board (SWB) created economic model (link to the final model version below) that incorporates both water loss and economic metrics.
  • The majority of the economic model’s inputs can be customized by a supplier, if documentation is submitted to the SWB.  However not all inputs are weighted equally in the model.  Additional information on model inputs can be found below:


April 2023

Update provided by Amy Talbot, former Chair of CA-NV AWWA Water Loss Committee

The SB 555 Water Loss Regulation was adopted on October 19, 2022, by the State Water Board (SWB).  Here is final Board Resolution and final draft regulation documents.   This water loss targets created in this regulation are also incorporated into the SB 606/AB 1668 supplier budget calculations.

We are now in implementation mode!  There are several required actions for suppliers in 2023 including:

  • Data Quality/Apparent Loss and Pressure Management Questionnaires– Due July 1, 2023
    • The SWB staff are currently updating all the questionnaire documents.  SWB staff indicated the updated questionnaires will be similar to previous drafts and should be posted here at the end of May.
    • Note: The pressure management questionnaire will need to be updated again by July 1, 2026.
    • SWB staff reached out to ACWA to help identify 10-15 suppliers that would be willing to pilot the updated set of water loss questionnaires before the final documents are posted online.  Email Chelsea if you are interested in participating ([email protected]).
  • Initial Economic Model Input Parameter Adjustments - Due July 1, 2023
    • For those suppliers seeking a more locally appropriate water loss target, the SWB provides the opportunity to submit documentation justifying changes to the model’s statewide default input values.  Suppliers can choose which default inputs to modify, however, the modifications must be accompanied with supplier specific backup documentation.  The SWB produced a guidance document that outlines what documentation is required for specific input adjustments.
    • While suppliers can technically submit adjustment requests anytime, if requests are submitted after July 1, 2023, suppliers will need to provide additional information about why documentation could not have been submitted before the initial deadline of July 1, 2023.
      • Relevant Regulation Text: “Parameter adjustment requests submitted after July 1, 2023, will not be accepted unless accompanied by a satisfactory explanation for the supplier’s inability to submit that request prior to that date. Satisfactory explanations include that the supplier, with reasonable diligence, did not yet have access to measured data necessary for parameter calculations or that the supplier is replacing obsolete data with more recent, higher-quality data.”
    • Adjustment documentation must be submitted to [email protected].
    • Examples of previous supplier adjustment documentation submitted to and approved by SWB staff here.  Thank you, city of Sacramento and STPUD.
    • CA NV AWWA hosted a supplier focused model adjustment training in January 2022 to help suppliers get started on this process.  The training PowerPoint can be found here. Please note the presentation recording will be updated soon.
    • Not sure what your supplier water loss target is?  Find out here.  File updated April 7, 2023.

The SWB staff contact for the water loss regulation is Beti Girma.  Please contact Beti with any additional questions at [email protected].


December 2022

Update provided by Amy Talbot, former Chair of CA-NV AWWA Water Loss Committee

The State Water Board (SWB) adopted the water loss regulation on October 19th at their Board meeting.  

The only change from the proposed materials is the addition of a formal assessment/review of the regulation’s implementation after the first compliance period in 2028 that was added to the adoption resolution (not regulation text).  Here is the final resolution with the additional text (#5 on page 4).

Next Steps for Suppliers:

  • Check your baseline audit data (2017-2020 audits) for any errors and/or update audits with any newly available information. This set of audits is the baseline data that feeds into the SWB economic model to produce a supplier’s water loss standard(s).  If you make changes to your annual audits, they must be re-validated and re-submitted to DWR.  If you identify any issues or errors, contact DWR with edits and/or to resubmit audits at [email protected]
  • Check your supplier/system water loss standards. The SWB has released the most current water loss standards here.  Review your supplier/system audits to determine if a review of annual audit data or customization of the economic model inputs is necessary.  If you have any questions regarding your standards, contact the SWB staff at [email protected].
  • OPTIONAL: A supplier can choose to customize the economic model default inputs to produce a revised water loss standard.  Not sure where to start?  The CA NV AWWA Model Input Training for Suppliers and associated resources referenced above can help.  Although you can officially submit model input customizations at any time during the regulation period, suppliers should aim for submitting changes to SWB staff before July 1, 2023.  After this date, a supplier will also have to submit justification as to why the input customizations were not possible by July 1, 2023.

Water Loss Standard Requirements and Timeline:

More information:  CalWEP December Plenary


October 2022

Update provided by Amy Talbot, former Chair of CA-NV AWWA Water Loss Committee

The State Water Board staff will present the SB 555/SB 606/AB 1668 Water Loss Regulation for Board approval at their October 19th Board meeting (starting at noon).  Please see the agenda (page 3, item #9), item details, and draft resolution for approval for more information. 

SWB staff will be posting an updated version of the regulation text soon, however, staff stated via email “there will be no substantive changes between the reg text that was posted on September 2nd and the one that will be published.”   In the meantime, the September 2nd regulation text (tab 3) and the September 9th supplier targets/standards (under water loss model, standards and questionnaires heading, which also includes the economic model) can be reviewed.  I will send the updated regulation text as soon as it is available.  It is unclear if the supplier targets will also be updated.  We do not anticipate any additional changes to the economic model.

Stakeholders are welcome to attend the October 19th Board meeting online or in person to provide comments.  More information on how to provide comments here


September 2022

The 2nd formal rulemaking for the water loss regulation started on Friday, September 2nd and will run through Monday, September 19th at noon PST.

Here is the official notice and revised regulation text.  An updated version of the economic model and supplier specific water loss standards has also been posted here (dated September 2nd). 

NOTE #1:  Please check your supplier standards as they may have changed, especially those systems that had an initial benefit cost ratio <1 as your standard has reverted back to current loss. 

Note #2:  It looks like at least some of the small systems between 200 and 3,000 connections are not listed in the updated standards spreadsheet.  An inquiry has been sent to State Water Board staff to figure out why they were left out.

Main changes in regulation text and model between the August 8th version and the September 2nd version include:

  • Changes to the definition of urban retail water supplier regarding small systems
  • Error corrections to the leak volume related model calculations (shouldn’t change supplier standards overall but will change Benefit Cost Ratio for some suppliers)
  • Changes to the “off ramp” option text (only available as an option for suppliers with loss 16 gallons per connection per day or less that also meet a bunch of data quality criteria)
  • Overinvestment was removed and replaced with long term cost effectiveness

Next Steps:

The water loss coalition (ACWA, CMUA, CA NV AWWA and CWA) are working on a draft comment letter based on the various meetings we’ve had over the last month or so.  More information on the draft letter to come soon!

If you are interested in submitting a comment letter by the September 19th at noon PST deadline:

  • Send email to [email protected]. The State Water Board requests but does not require that email transmission of comments, particularly those with attachments, contain the regulation package identifier “Comment

Letter – Proposed Water Loss Performance Standards” in the subject line to facilitate timely identification and review of the comment

  • Comments should be focused on the CHANGES made after the February 2022 regulation text and model versions.

January 2022

  • Formal rulemaking started Dec. 24th and comments are due to the SWRCB by Feb. 11th
  • If there are major changes an additional 15-day comment period will be added
  • Regulation is expected to be adopted in Q2

For more updates about major changes and next steps, please review these slides prepared by Amy Talbot at RWA for CA-NV AWWA Water Loss Committee on January 13, 2022.

November 2021

The Standardized Regulatory Impact Assessment (SRIA) Report was publicly posted on October 13, 2021.  The SRIA is a required economic analysis of the costs and benefits of implementing the water loss regulation.  The SRIA is developed by the State Water Board and submitted to the California Department of Finance.  There is no formal comment period on the document. However, suppliers can submit informal comments to State Water Board staff.  This is the first step to initiate the formal rulemaking process, which is expected to start on December 24, 2021.  See timeline below for more information about the formal rulemaking process.

August 2021

The updated economic model was released in April 2021. The SWRCB is encouraging water suppliers to customize the inputs and submit to SWRCB staff for approval an updated 2028 target. Formal rulemaking is expected to start in Fall 2021.

Economic model found here.

Timeline of Events

  • April 15 – Revised draft economic model and performance standards
  • Ongoing discussions:
    • CMUA Compliance Path – >30% reduction
    • Changes to economic model
    • Supplier option to customize economic model inputs
    • Recent addition of apparent loss target (only real loss target originally)
  • October 13, 2021 – Release of the Standardized Regulatory Impact Assessment (SRIA)Report -Required economic analysis of regulation implementation
    • No formal comment period, CA NV AWWA to submit informal comments on November 19, 2021
  • Mid December 2021– Public posting of formal rulemaking materials (including proposed water loss regulation text)
  • December 24, 2021 – Start of formal rulemaking process, initial 45-day comment period (can extend up to 365 days)
  • January 3rd-7th, 2022  –State Water Board to host public workshop to discuss additions and change to the proposed water loss regulation
  • January 5, 2022 – ACWA/CMUA Workgroup meeting to discuss proposed water loss regulation
    • Contact Chelsea Haines, ACWA, for more information
  • Late January/Early February 2022 – State Water Board to host public hearing for stakeholder comments on proposed water loss regulation
    • Comments can be submitted to the State Water Board via email anytime during the 45-day comment period
  • September 2022 – Second comment period – 15 days
    • Comments can be submitted to the State Water Board by deadline
  • October 19, 2022 -  Regulation Adopted by State Water Board
  • TBD - Effective date of approved Regulation
  • January 1, 2024 – Suppliers start reporting progress toward water loss standards
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