Comparison of MCLs and PHGs for Regulated Contaminants in Drinking Water
Last Update: June 12, 2008
This page compares maximum contaminant levels (MCLs) adopted by CDPH and public health goals (PHGs) established by Cal/EPA's Office of Environmental Health Hazard Assessment (OEHHA).
MCLs
MCLs are health protective drinking water standards to be met by public water systems. MCLs take into account not only chemicals' health risks but also factors such as their detectability and treatability, as well as costs of treatment. Health & Safety Code §116365(a) requires CDPH to establish a contaminant's MCL at a level as close to its PHG as is technically and economically feasible, placing primary emphasis on the protection of public health (see the MCL process). Along with the MCL, a regulated chemical also has a detection limit for purposes of reporting (DLR), the level at which CDPH is confident about quantification being reported.
PHGs
PHGs are concentrations of drinking water contaminants that pose no significant health risk if consumed for a lifetime, based on current risk assessment principles, practices, and methods. OEHHA establishes PHGs pursuant to Health & Safety Code §116365(c) for contaminants with MCLs, and for those for which CDPH will be adopting MCLs.
Public water systems use PHGs to provide information about drinking water contaminants in their annual Consumer Confidence Reports. Certain public water systems must provide a report to their customers about health risks from a contaminant that exceeds its PHG and about the cost of treatment to meet the PHG, and hold a public hearing on the report.
Review of MCLs in Response to PHGs
Once OEHHA establishes or revises a PHG for a contaminant with an MCL, CDPH determines whether the MCL should be considered for possible revision. For a chemicals so designated, CDPH subsequently conducts an in-depth risk management analysis to determine whether or not to propose a revision. For more information, see MCL review status.
Go to MCLs, DLRs, and PHGs (Excel)