Water System Resources

Baseline vs Initial Inventory

The Lead and Copper Rule Improvements (LCRI) require community and non-transient non-community water systems to develop an updated Initial Lead Service Line Inventory (LSLI) of service line and connector locations and materials in their distribution system, known as the Baseline Inventory. Baseline Inventories are due November 1, 2027, and must be submitted to the Division of Drinking Water (DDW) Lead and Copper Rule (LCR) Unit for review and approval.

The Initial LSLI required under the Lead and Copper Rule Revisions (LCRR) was due on October 16, 2024. Water systems that have not submitted their Initial LSLI are out of compliance with the LCRR inventory requirement and should contact the LCR Unit to determine their next steps and begin working on their Baseline Inventory.

Inventory Submission

The preferred method for submitting the Baseline Inventory is by email to the LCR Unit at DDW-LCR@waterboards.ca.gov.

Submission through the Lead Service Line Inventory Portal is also acceptable starting January 11, 2027. A WBKey account is required to submit a Baseline Inventory in the LSLI Portal and one account per water system is recommended.

• LSLI Submission Portal (ca.gov)
• LSLI Portal User Guidance Document
• WBKey Account Getting Started Guide

Inventory Templates

Template Update

The Division of Drinking Water (DDW) inventory spreadsheet template was updated in October 2026 to help water systems comply with the new LCRI Baseline Inventory requirements for service lines and connectors. DDW strongly recommends, but does not require, water systems to use the DDW template.

If exporting data from a different database, use the Metadata Guide below to add the required information for the Baseline Inventory. If you have compatibility issues with Excel or need a template for over 20,000 service lines, please contact the LCR Unit.

• LCRI Inventory Template – Up to 100 Service Lines
• LCRI Inventory Template – Up to 500 Service Lines
• LCRI Inventory Template – Up to 5,000 Service Lines
• LCRI Inventory Template – Up to 20,000 Service Lines
• LCRI Inventory Template Metadata Guide

Data Transfer Service for New Template

To complete the Baseline Inventory, Initial Inventory data may need to be transferred to the new template. Please submit a Transfer Request Form to request the LCR Unit transfer your Initial Inventory data to the new Baseline Inventory template for you.

• Transfer Request Form

Inventory Guidance and Resources

LCRI Baseline Inventory

Each community and non-transient non-community water system must maintain the required inventory information described in the resources below.

• Baseline Inventory Instructions (Oct 2026)
• Baseline Inventory Template Walkthrough Video (Oct 2026)
• Baseline Inventory Zoom Training (Video | PDF, Oct 2026)

LCRR Initial Inventory

Most of the Initial Inventory guidance below can assist water systems in developing the service line portion of the Baseline Inventory.

• Inventory FAQ (updated Jul 2025)
• Inventory Methods (updated Dec 2023)
• Initial Inventory Overview (Video | PDF, Jul 2024)
• Initial Inventory for Small Systems (Video | PDF, Sep 2024)
• LCRR - Part 1: Overview
• LCRR - Part 2: Starting the Private Side Inventory
• US EPA Guide for Developing and Maintaining a Service Line Inventory (Aug 2022)
• US EPA Guide for Small Entity Compliance (Jun 2023)
• ASDWA papers, communications, webinars, and resources for the LCRR

Summary of Inventories

*Typically, this is the utility-owned portion which includes the pipe, tubing, and fittings connecting a water main to an individual water meter or service connection.

SB427 Lead Service Line Requirement

Resources for lead service line inventory and replacement under Senate Bill No. 427 (SB427) are available at the Lead Service Line Replacement Collaborative website. For more information, please visit the Health and Safety Code 116885 User Service Line Inventory page.

Public Notification Templates

90th Percentile Lead Action Level Exceedance (Tier 1)
All community and non-transient non-community water systems are required to issue a Tier 1 public notice within 24 hours after discovering a 90th percentile lead action level exceedance (ALE) starting October 16, 2024. (40 CFR 141.202(a)(10)).  See the standard operating procedure below for instructions on what to do if your system has a 90th lead ALE.

• PN Standard Operating Procedure - Lead ALE
• PN Template - Lead ALE (English)
• PN Template - Lead ALE (Spanish)
• PN Certification - Lead ALE

Failure to Complete an Initial Inventory by October 16, 2024 (Tier 2/Tier 3)

Water systems that fail to develop an initial service line inventory by 10/16/2024 must provide Tier 2 public notice to its customers within 30 days. Systems that fail to submit an inventory by the deadline must provide Tier 3 public notice to its customers or include the Tier 3 notice in their Consumer Confidence Report (CCR) for that year (40 CFR 141.203, 40 CFR Appendix A to Subpart Q – I.C.1).

• PN Template - Failure to Complete Initial Inventory
• PN Template - Failure to Complete Initial Inventory (Spanish)
• PN Certification - Failure to Complete Initial Inventory

Notification for Lead, GRR, and/or Unknown Service lines

Pursuant to 40 CFR 141.85(e), water systems with known or potential service lines containing lead must provide public notice to all persons served by lead, galvanized requiring replacement (GRR) and/or lead status unknown (unknown) service lines. The first notification must be posted by November 15, 2024, and repeated annually until the service line is classified as non-lead. Notifications must be certified to DDW by July 1 of the following calendar year.

• PN Template - Lead Service Lines
• PN Template - GRR Service Lines
• PN Template - Unknown Service Lines
• PN Template - Lead, GRR, or Unknown Service lines (Spanish)
• PN Certification - Systems with Lead, GRR, and/or Unknown Service Lines

Inventory Public Accessibility

Water systems must make their lead service line inventory publicly accessible. For systems serving over 50,000 persons, inventories must be accessible online.

Water systems with only non-lead service lines in their inventory may provide a written statement instead of a publicly accessible inventory. The written statement must include a general description of the methods used to determine service line materials as noted in the templates below.

• Non-lead Statement Template - All Service Lines Verified
• Non-lead Statement Template - Stratified Random Sampling
• Non-lead Statement Template - Interpolation
• Non-lead Statement Template - Interpolation, Systems with Less Than 1,500 Services
• Non-lead Statement Template - Other Method(s) Used

Consumer Confidence Reports (CCR)

Public water systems are required to provide information to their customers and consumers about the quality of their drinking water in their CCR. Updates to the mandatory lead and copper health effects language in the CCR will be required under the LCRR and LCRI. Instructions to access the service line inventory or the non-lead statement must be included in water systems’ annual CCR.

Implementing the Lead Public Education Provision

• US EPA LCR Public Education Guide for Community Water Systems
• US EPA LCR Public Education Guide for Non-Transient Non-Community Water Systems

Under both the LCR and LCRI, water systems are required to periodically obtain tap samples for lead and copper testing. Systems that have a 90th percentile lead action level exceedance (ALE) must notify DDW, US EPA, and all consumers within 24 hours of discovery. Below are guidelines and forms to assist with 90th percentile level calculation and reporting to meet current LCR requirements.

• DDW LCR Tap Sampling Guidance Document
• DDW LCR Tap Sampling Reporting Form
• DDW LCR Tap Sampling Site Change Form
• US EPA memo clarifying recommended tap sampling procedures for the LCR
• US EPA Suggested Homeowners Tap Sample Procedures