Page 4 - Consumer Confidence Report 2024

pg. 3
Water Quality Standards
In order to ensure that tap water is safe to drink, the United States Environmental
Protection Agency (USEPA) and the State Water Resources Control Board,
Division of Drinking Water (DDW) prescribe regulations that limit the amount of
certain contaminants in water provided by public water systems. The U.S. Food
and Drug Administration regulations and California law also establish limits for
contaminants in bottled water that provide the same protection for public
health.
Definitions, Acronyms, and Abbreviations
Drinking water standards established by USEPA and DDW set limits for
substances that may affect consumer health or aesthetic qualities of drinking
water. The chart in this report shows the following types of water quality
standards:
Maximum Contaminant Level (MCL): The highest level of a contaminant
that is allowed in drinking water. Primary MCLs are set as close to the PHGs
(or MCLGs) as is economically and technologically feasible. Secondary
MCLs are set to protect the odor, taste, and appearance of drinking water.
Maximum Residual Disinfectant Level (MRDL): The highest level of a
disinfectant allowed in drinking water. There is convincing evidence that
addition of a disinfectant is necessary for control of microbial contaminants.
Primary Drinking Water Standard: MCLs for contaminants that affect health
along with their monitoring and reporting requirements and water treatment
requirements.
Regulatory Action Level (AL): The concentration of a contaminant, which, if
exceeded, triggers treatment or other requirements that a water system
must follow.
Notification Level (NL): An advisory level which, if exceeded, requires the
drinking water system to notify the governing body of the local agency in
which users of the drinking water reside (i.e. city council, county board of
supervisors).
In addition to mandatory water quality standards, USEPA and DDW have set
voluntary water quality goals for some contaminants. Water quality goals are
often set at such low levels that they are not achievable in practice and are not
directly measurable. Nevertheless, these goals provide useful guideposts and
direction for water management practices. The chart in this report includes
three types of water quality goals:
Maximum Contaminant Level Goal (MCLG): The level of a contaminant in
drinking water below which there is no known or expected risk to health
MCLGs are set by USEPA.
Maximum Residual Disinfectant Level Goal (MRDLG): The level of a drinking
water disinfectant below which there is no known or expected risk to health.
MRDLGs do not reflect the benefits of the use of disinfectants to control
microbial contaminants.
Public Health Goal (PHG): The level of a contaminant in drinking water below
which there is no known or expected risk to health. PHGs are set by the
California Environmental Protection Agency.