Drinking Water Health Advisories

The U.S. Environmental Protection Agency (EPA) develops Health Advisories (HAs) to provide information on contaminants that can cause human health effects and are known or anticipated to occur in drinking water. These HAs are not enforceable. The HAs are intended to provide technical guidance to public water supply systems and public health officials when contamination situations arise. The guidance includes limits in drinking water below which health effects are not expected to occur. The HAs are updated as necessary. The tables contain HA values for certain contaminants based on non-cancer health effects for different exposure duration: one-day, ten-day, and lifetime.

2018 Edition of the Drinking Water Standards and Health Advisories Tables

One-day or 10-day health advisories are concentrations in drinking water that are not expected to cause any adverse health effects for up to one day or 10-days of exposure. These HAs are intended to protect a 10-kg (22 lbs.) child consuming 1 liter of water per day. They are considered acute or short-term health advisories.

Lifetime health advisories are concentrations that are not expected to cause adverse non-carcinogenic health effects after a lifetime of exposure. The Lifetime HA is based on exposure of a 70-kg (154 lbs.) adult consuming 2 liters of water per day, for a 70-year lifetime. It is considered a chronic or long-term health advisory.

Unregulated Contaminant Monitoring Rule: The Unregulated Contaminant Monitoring Rule (UCMR) is the rule that requires systems serving more than 10,000 people and selected smaller systems to monitor during a specific time period for a group of contaminants that could be present in drinking water and which have adverse human health effects. The purpose of the UCMR is to provide occurrence data that is used to determine if a specific contaminant should be regulated on a national basis. The current UCMR is UCMR5. More information on the UCMR is available on the EPA website.

Any community system that participates in UCMR monitoring must also include in its annual Consumer Confidence Report that the data is available, and, if a contaminant was detected, must contain the average and range at which the contaminant was detected.

Home Water Treatment Devices: The Iowa Department of Public Health administers the Water Treatment System Registration Program, which is responsible for:

• Confirming that water treatment systems sold in Iowa with claims to reduce health-related contaminants have appropriate third-party verification of the claims.
• Reviewing third-party testing agencies to ensure proper qualifications and capabilities.
• Maintaining a registry of water treatment systems that comply with Iowa law.
• Technical assistance to consumers and preliminary investigation of complaints regarding sale of unregistered water treatment systems or that are making unsubstantiated claims.

See the IDPH website for more information and registry lists.

Contaminants of Current Interest

EPA has over 70 health advisories for contaminants that are not regulated by a maximum contaminant level, maximum residual disinfectant level, or treatment technique. Cyanotoxins and manganese are contaminant groups of public interest at this time.

Cyanotoxin Information

Cyanobacteria (blue-green algae) are photosynthetic bacteria that share some properties with algae and are found naturally in all surface waters, both freshwater and marine.  Cyanobacteria helped form the Earth’s atmosphere by producing oxygen from photosynthesis.

There are several types of cyanobacteria, some of which can generate one or more chemicals that are toxic to humans and animals. When conditions are favorable, cyanobacteria can rapidly multiply and cause algal blooms. Sometimes the cyanobacteria produce toxins that can be harmful. Cyanotoxins, specifically microcystin, were the cause of the “Do Not Use” water event in Toledo, Ohio, for several days in August 2014.

Toxin-producing strains in the Midwest are typically seen in early summer and late summer. Under conditions that are not fully understood but involve light and nutrients, some types of cyanobacteria can form toxins. Both toxic and non-toxic varieties of the most common cyanobacteria can be present at the same time. It is impossible to tell whether or not a species is producing toxins just by looking at it.

Factors that affect cyanobacterial bloom formation and persistence include:

• Light intensity and total sunlight duration: stronger light and longer duration
• Nutrient availability (both nitrogen and phosphorus)
• Water temperature: warmer temperatures, in the range of 60°F – 80°F

Adverse health effects

Cyanotoxins can cause skin rashes, nausea, diarrhea, fatigue, and can cause toxic effects to the nervous system, liver, and kidneys.

EPA health advisories

In 2015, EPA issued 10-day health advisory levels for two cyanotoxins in finished (treated) drinking water: microcystin and cylindrospermopsin. These are non-regulatory levels that public water supply systems can use to interpret the results of their voluntary monitoring.

Microcystin:

• Children 5 years of age and younger, and pregnant women: 0.3 ug/L (microgram per liter, or parts per billion)
• Reminder of population: 1.6 ug/L

Cylindrospermopsin:

• Children 5 years of age and younger, and pregnant women: 0.7 ug/L
• Remainder of population: 3.0 ug/L

Iowa Microcystin Surveillance Study

From July 2016 to June 2017, many of the surface water and influenced groundwater public water supply systems in Iowa participated in a year-long study that monitored the microcystin level in the raw water each week. If microcystin was detected, the system followed with finished (treated) water sampling.  

Public Notice examples for microcystin and cylindrospermopsin are listed on the DNR's Public Notice webpage.

In the 2016-2017 Iowa study, there was no confirmed detection of microcystin in the finished (treated) drinking water at any of the participating public water supply systems. Microcystin Surveillance Study of Iowa's Public Water Supply Systems, July 2016 - June 2017: Report of Findings

Resources

• AWWA-WRF: Managing Cyanotoxins in Drinking Water: A Technical Guidance Manual for Drinking Water Professionals, September 2016
• Center for Disease Control’s Cyanobacteria Fact Sheet – Frequently Asked Questions
• EPA: Cyanobacteria and Cyanotoxins - Information for Drinking Water Systems, June 2019
• EPA: Recommendations for Public Water Systems to Manage Cyanotoxins in Drinking Water, June 2015
• EPA Harmful Algal Blooms and Cyanobacteria website
• Iowa DNR Beach Monitoring Website, which lists the microcystin testing done on a weekly basis during the recreational season at state beaches.
• Ohio’s Public Water System Harmful Algal Bloom Response Strategy
• Ohio’s Harmful Algal Bloom website

What is manganese?

Manganese is a common, naturally-occurring mineral found in rocks, soil, groundwater, and surface water.

Manganese in the human diet

Manganese is a natural component of most foods, and is an essential nutrient. Eating a small amount of it each day is important to stay healthy. The majority of manganese exposure in the general population comes from food. Grains, beans, nuts, and teas are rich in manganese, and it is also found in infant formula. A normal diet typically provides adequate manganese intake. The principal source of exposure to manganese is from food, but in situations where manganese levels in drinking water are elevated, the contribution from drinking water can increase the overall intake of manganese. Manganese is found naturally in groundwater and surface waters in Iowa. Manganese may become noticeable in water at levels greater than 0.05 milligrams per liter (mg/L, or parts per million), above which level the water may have a brown color and may leave black deposits on sinks and bathroom fixtures.

Adverse human health effects

Some people who may be more sensitive to manganese would be those who absorb greater amounts of manganese or those who excrete less, which includes bottle-fed infants under 6 months old, the elderly, and those with liver disease. Some studies suggest that prenatal and early childhood exposures to manganese can have adverse effects on learning and behavior. When manganese levels in drinking water are above 0.3 mg/L, infants under 6 months of age should immediately stop consuming the water and formula that was prepared with the tap water.

Many years of exposure to high levels of manganese can cause harm to the nervous system, including tremors, shaking, and an unsteady gait, which are characteristic of very high exposure to manganese. The US EPA’s health advisory is intended to protect against this effect.

Manganese is poorly absorbed through the skin. There are no concerns about manganese exposure through skin contact with food or water containing manganese. Anyone concerned about their health from manganese exposure should discuss their concerns with their healthcare provider.

Manganese health advisories in drinking water

EPA has three health advisories for manganese in drinking water:

The US EPA health advisory levels of 0.3 mg/L and 1 mg/L were set based upon typical daily dietary manganese intake levels not known to be associated with adverse health effects. This does not imply that intakes above these levels will necessarily cause health problems. As a precaution, the general population should consider limiting their consumption of drinking water which has levels of manganese above the EPA health advisory to decrease their exposure and to decrease the possibility of adverse neurological effects.

Public Notice examples for manganese are listed on the DNR's Public Notice webpage.

Manganese regulation

Currently, there is no regulatory limit for manganese in drinking water set by the EPA or the DNR. EPA has set a secondary maximum contaminant level for manganese, which addresses levels that cause aesthetic concerns, such as staining and taste. EPA has set this non-enforceable guideline at 0.05 mg/L of manganese in drinking water. EPA is the process of determining whether to regulate manganese in drinking water due to updated health effects information and additional occurrence data. As part of that process, EPA included manganese in the UCMR4, with monitoring to be completed in 2020. In addition to the occurrence data from UCMR4, EPA will also consider the health effects in their regulatory determination and evaluate potential risks to children and infants based on recent studies.

How do I find out about manganese levels in my drinking water?

If you obtain your water from a public water supply system, contact your public water supply system and request the concentrations of manganese. Please be aware that not all systems are required to test for manganese.

If you obtain your water from a private well and suspect high manganese in your drinking water, contact your local county health department or visit the DNR’s Private Well Program website. This website includes testing and treatment information.

Treatment to remove manganese

Do not boil the water because boiling increases the manganese levels through concentration. Filtration can be effective at lowering manganese levels, however any treatment device requires regular maintenance and cleaning.

The DNR Private Well Program website has treatment information for homeowners, including a reference to the SHL Well Water Quality and Home Treatment Systems brochure. The Iowa Department of Public Health (IDPH) maintains the registry of water treatment devices on their website.

Resources

IDPH Contact Information: For additional health related inquiries regarding manganese in drinking water, contact Mindy Uhle at 515-499-1395 or melinda.uhle@idph.iowa.gov.