Drinking Water Notification Level for Manganese
Last Update: February 22, 2005
CDPH's drinking water notification level for manganese is 0.5 milligram per liter (0.5 mg/L).
Manganese is a required nutrient. A healthful diet provides adequate manganese for good nutrition. Typical dietary intake of about 1–10 mg manganese per day appears adequate for daily needs, according to ATSDR (2000).
However, manganese at very high levels can pose a neurotoxic risk (ATSDR, 2000; US EPA, 1996). For example, neurologic damage (mental and emotional disturbances, as well as difficulty in moving—a syndrome of effects referred to as "manganism") has been reported to be permanent among manganese miners exposed to high levels of airborne manganese for long periods of time. Lower chronic exposures in the workplace resulted in decrements in certain motor skills, balance and coordination, as well as increased memory loss, anxiety, and sleeplessness (ATSDR, 2000). USEPA (1996), in developing an oral reference dose for manganese based on dietary intake, mentions an epidemiological study in Greece that showed an increase in neurologic effects such as weakness and fatigue, disturbances in gait, and neuromuscular effects, in people whose drinking water contained 1.6 to 2.3 mg/L. Uncertainties about the levels of dietary manganese and the amount of drinking water consumed did not enable USEPA to use these data for risk assessment purposes.
ATSDR (2000) reports several studies that showed decreased ability in neurobehavioral performance testing and in several educational parameters, in children exposed to high level of manganese in drinking water and diet for at least several years.
Children are considered to be particularly susceptible to possible effects of high levels of manganese exposure because they absorb and/or retain more manganese than adults (ATSDR, 2000; USEPA, 1996).
Attention to the potential health concerns of high levels of manganese in drinking water is appropriate, given the possibility of neurologic effects.
Manganese is regulated by a 0.05-mg/L secondary maximum contaminant level (MCL) (see drinking water regulations), a standard established to address issues of aesthetics (discoloration), not health concerns. Secondary MCLs are enforceable standards, but are applicable only to community systems. Thus, noncommunity systems, particularly nontransient noncommunity (NTNC) systems such as schools and workplaces, do not receive the benefits of the secondary standard.
Although the aesthetic effects related to elevated manganese in drinking water are likely to be encountered at concentrations below the notification level, the notification level provides an extra layer of protection to consumers of water from systems subject to the secondary MCL requirements.
A health-based notification level for manganese is helpful in addressing high manganese levels in drinking water sources, in several ways:
- It provides guidance and information to systems with manganese above the secondary MCL, as they deal with the regulatory requirements associated with exceeding the standard, i.e., addressing costs associated with treatment.
- It provides guidance to CDPH Drinking Water Program staff in evaluating waivers from treatment requirements to meet the secondary MCL. Currently, consumers are to be surveyed about their acceptance of exceeding a secondary MCL. A notification level allows health-based considerations to enter into the consumer survey and waiver from treatment process.
- It allows consumers of water from NTNC systems to be informed about the potential for health concerns associated with sources that have high levels of manganese.
When manganese is present in concentrations greater than the notification level, the following requirements and recommendations apply:
- Systems with drinking water sources with manganese concentrations greater than the notification level are required to notify local city and county governing bodies, just as for other contaminants with notification levels and for contaminants that exceed MCLs.
- Consumer notification is recommended at levels greater than the notification level. This may be handled through the water systems' annual consumer confidence reports. Other means could be used as well, if more appropriate, such as direct mailing, or posting a notice. These should be coordinated with the local CDPH Drinking Water Program district office.
- Source removal is recommended at ten times the notification level.
Monitoring for manganese is required within the framework of secondary MCL regulations, but generally not outside that framework. For sources not subject to the secondary MCL requirements, CDPH recommends analyses of sources that are near other sources that have very high manganese levels.
In 2003, when CDHS (the California Department of Health Services, now CDPH) established the 0.5-mg/L notification level (then called an "action level"), CDHS recommended follow-up monitoring for those systems that historically had shown manganese higher than the 0.5-mg/L concentration, but which lacked recent data. Current monitoring allows water systems to confirm earlier values, and to allow them to meet the requirement for notifying its local government body with timely information. If a water system chose not to take a contemporary follow-up sample for manganese analysis, then CDHS recommended notification of the governing body based on prior data. Consumer notification should follow the recommendations mentioned above.
For community systems subject to the secondary MCL monitoring and compliance requirements (22 CCR §64449) with manganese greater than the notification level, CDPH recommends that information about the health concerns associated with high manganese exposures be provided to consumers as part of the required consumer dissatisfaction determination.
Historically, about 30 percent of drinking water sources monitoring for manganese have reported detections, reflecting its natural occurrence, and about 20 percent have reported detections greater than the 0.05-mg/L secondary MCL. The detection limit for purposes of reporting (DLR), the level at which DHS is confident about the quantification of manganese's presence in drinking water, is 0.02 mg/L.
For example, monitoring results from 2001-2004 show that 276 sources from 199 systems reported a detection above 0.5 mg/L. [For purposes of comparison, there are ~12,000 sources belonging to ~4,400 community and NTNC systems.] Sources with a detection above 0.5 mg/L occurred in 42 of the state's 58 counties, most often in the counties of Sonoma (47 sources), San Diego (20), San Bernardino (15), San Luis Obispo (14), San Joaquin (14), Ventura (13), Santa Barbara (12), and Riverside (10).
| Drinking Water Sources with Manganese Detected above 0.5-mg/L* |
| Concentration |
No. of Sources |
No. of Systems |
No. of Counties |
| Mn > 0.5 mg/L |
276 |
199 |
42 |
| *These draft data are from manganese detections above 0.5 mg/L (2001 - 2004). In determining the number of sources for this table, agricultural wells and monitoring wells have been excluded. |
Readers interested in the levels of manganese in their drinking water should refer to their water systems' annual Consumer Confidence Reports (CCRs). A number of CCRs for California water systems are available on the US EPA's website.
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ATSDR, 2000, Toxicological Profile for Manganese, Agency for Toxic Substances and Disease Registry, September, 2000.
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US EPA, 1996, Manganese, Integrated Risk Information System, US Environmental Protection Agency, Reference Dose last updated May 1, 1996.