EDT Library and Water Quality Analyses Data and Download Page

Drinking Water Quality Data

To streamline the flow of water quality data, DDW launched a portal known as CLIP (California Laboratory Intake Portal) on September 1, 2021. This change to the electronic submission of water quality analyses replaces the WQM (Water Quality Management) portal and ensures that data from laboratories flow to DDW’s database of record, the Safe Drinking Water Information System (SDWIS). This process will not only allow for quicker compliance determinations but will also provide for improved data quality by ensuring that minimum data validations have been met. For more information about CLIP, please visit the following link – California Laboratory Intake Portal (CLIP) web page.

Monitoring Schedules

DDW's drinking water quality monitoring schedules identify upcoming required contaminant testing of drinking water for water systems in California. To access, go to the Drinking Water Watch website, enter the Water System Number or the Water System Name for which you would like to search and click the ‘Search For Water Systems’ button. You will then arrive at the ‘Water System Details’ page. On the left-hand side of the page, click the ‘Monitoring Schedules’ link to arrive at the ‘Monitoring Schedules’ page. On this page, you will have the option to click ‘Monitoring Schedules for All Sampling Points’ or to click on the three digit ‘Sampling Point’ link which corresponds to individual sources (PS Codes). Once a monitoring schedule is accessed, you can export to excel, pdf, or word.

Water Quality Database Files

For the Water Quality files available below, it is recommended that you copy the files into a folder on your drive and import into most well know database software programs, such as Microsoft Access, FoxPro, or Paradox. Note that spreadsheet programs such as Excel are not able to handle the sheer volume of records produced.

Notice to User of the Data – Care should be taken in interpreting the data. A single detection of a contaminant may not indicate contamination of a drinking water supply. If this detection is not confirmed with a follow-up detection, it may represent a false positive. Additionally, the presence of a contaminant in raw water at a given concentration does not necessarily mean that the water was served by the water system to its customers, or if served, that the contaminant was present at that concentration. Water systems may not use certain sources or may treat or blend them prior to service. Data that does not meet DDW data quality objectives is not included. Questions about contaminants in particular sources are best addressed by the specific public water system, or by the associated DDW District Office.

For data from 2011 to present

As mentioned at the top of this page, DDW now receives water quality data via CLIP with the data then being passed to SDWIS. In addition to implementing CLIP, DDW copied water quality data from WQM to SDWIS for the time period spanning January 1, 2011 up to September 1, 2021. As a result, the following .TAB files extracted from SDWIS represent data that was received via WQM (prior to September 1, 2021) and via CLIP (post September 1, 2021).

[Note - TAB files are "tab" delimited files. If using Access to open these files, ensure that the delimiter is set to "tab". Also, due to the size of these files, it is recommended that the files be "linked" instead of "imported" into Access in order to prevent the application from crashing.]

  • SDWIS4.tab – contains data from January 1, 2023 to Present (last updated December 17, 2024)
  • SDWIS3.tab – contains data from January 1, 2019 through December 31, 2022
  • SDWIS2.tab – contains data from January 1, 2015 through December 31, 2018
  • SDWIS1.tab – contains data from January 1, 2011 through December 31, 2014

Data Dictionary – Supporting file for SDWIS.CSV files (last Update December 24, 2021)

For historical data, from 1974 to 2010
The following historical water quality data are available to download and are divided among three files in both .DBF and .CSV formats (Chemhist, Chemarch, and Chemxarc). There are also four supporting data files in both .DBF and .CSV formats (Siteloc, Watsys, Lab, and Storet) along with a Word file that provides explanation.

CHEMHIST contains chemical data from 2008 through 2010

CHEMARCH.ZIP contains chemical data from 2000 through 2007

CHEMXARC contains chemical data from 1974 through 1999

Supporting database files - Last Update August 16, 2021

Drinking Water Source identification number (PS Code), name and type

Water Systems identification number, name, and address

Laboratories reporting water quality analyses

Chemical (Storet) Reported

Information for Laboratories