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Monitoring and Reporting

Monitoring and Reporting

U.S. EPA sets national limits on contaminant levels in drinking water to ensure that the water is safe for human consumption. These limits are known as maximum contaminant levels (MCLs). For some regulations, U.S. EPA has established treatment techniques in lieu of a MCL to control unacceptable levels of contaminants in water by measuring the level of treatment. To ensure drinking water safety, public water systems are required to test their water for contaminants on a regular basis. The tests must be conducted at laboratories that are certified to perform such testing.

Generally, the larger the population served by a water system, the more frequent the monitoring requirements. However, the frequency varies depending on which contaminant is being evaluated and the type of source water used by the public water system (e.g., surface water systems and systems that use ground water under the direct influence of surface water typically monitor more frequently than a ground water system).  Monitoring requirements also vary by public water system type, which is based on how long a person is likely to have access to the water. 

Typically, testing would be most limited at a church that people attend only once per week, more expanded at a school or office building, and most extensive in a village or city. This is because the health effects of some contaminants are acute, such as E. coli bacteria, meaning they have the potential to pose an immediate risk to health. Other health effects are chronic, meaning that adverse health effects may result if the contaminant is consumed over an extended period of time. Examples of contaminants with chronic effects include arsenic and lead. Some contaminants can aesthetically impact drinking water, meaning the effects are in appearance or odor. Examples of these contaminants include iron or sulfate.

  • Microbiological contaminants, such as viruses and bacteria, which may come from sewage treatment plants, septic systems, agricultural livestock operations and wildlife
  • Inorganic contaminants (IOCs), such as salts and metals, which can occur naturally or result from urban stormwater runoff, industrial or domestic wastewater discharges, oil and gas production, mining or farming
  • Synthetic organic chemicals (SOCs), such as pesticides and herbicides, which may come from a variety of sources such as agriculture, stormwater runoff and residential uses
  • Volatile organic chemicals (VOCs), such as industrial chemicals and solvents, which can be byproducts of industrial processes and petroleum production, and can also come from gas stations, urban stormwater runoff and septic systems
  • Radiological contaminants (Rads), which can be naturally occurring or be the result of oil and gas production and mining activities
  • Disinfection byproducts (DBPs), which can form when disinfectants such as chlorine, chlorine dioxide or ozone react with organic and inorganic substances present in the raw water.

More detailed information on specific contaminants can be found in the Common Contaminants section tab.


Reference Information

Monitoring Schedules

View monitoring schedules using the drop-down list below. The list will be updated whenever revised schedules are generated. If you have any questions regarding specific monitoring requirements, please contact one of the following staff at (614) 644-2752:

Current Monitoring Schedules By County

Adams Darke Hocking Miami Scioto
Allen Defiance Holmes Monroe Seneca
Ashland Delaware Huron Montgomery Shelby
Ashtabula Erie Jackson Morgan Stark
Athens Fairfield Jefferson Morrow Summit
Auglaize Fayette Knox Muskingum Trumbull
Belmont Franklin Lake Noble Tuscarawas
Brown Fulton Lawrence Ottawa Union
Butler Gallia Licking Paulding Van Wert
Carroll Geauga Logan Perry Vinton
Champaign Greene Lorain Pickaway Warren
Clark Guernsey Lucas Pike Washington
Clermont Hamilton Madison Portage Wayne
Clinton Hancock Mahoning Preble Williams
Columbiana Hardin Marion Putnam Wood
Coshocton Harrison Medina Richland Wyandot
Crawford Henry Meigs Ross  
Cuyahoga Highland Mercer Sandusky  

Current Revised Schedules by Month

January April July October
February May August November
March June September December

Sample Collection Services List

This list contains labs and sampling services that can assist you with collecting and analyzing a water sample:

Certified Labs Lists

The following laboratories have been approved by Ohio EPA's Laboratory Certification program, which ensures laboratories are able to perform accurate testing using U.S. EPA approved Methods.

For more information about certified laboratories, please consult the laboratory certification page.

Common Contaminants 

Total coliform bacteria are naturally present in the environment and are used as an indicator that other potentially-harmful bacteria may be present. If total coliform bacteria are present, the sample results will be "positive." "Negative" means total coliform bacteria are not present in the sample.

E. coli and fecal coliform bacteria are bacteria whose presence indicates that the water may be contaminated with human or animal wastes. Microbes in these wastes can cause short-term effects, such as diarrhea, cramps, nausea, headaches or other symptoms. They may pose a special health risk for infants, young children, some of the elderly and people with severely compromised immune systems. 

Nitrate is a chemical contained in fertilizer and human and animal wastes. Infants younger than six months who drink water containing high levels of nitrate could become seriously ill and, if untreated, may die.  Symptoms include shortness of breath and blueness of the skin. 

Arsenic is a naturally occurring chemical. Some people who drink water containing high levels of arsenic over many years could experience skin damage or problems with their circulatory systems and may have an increased risk of getting cancer. 

Total trihalomethanes are byproducts formed as a result of disinfection. Some people who drink water containing high levels of trihalomethanes over many years may experience problems with their liver, kidneys or central nervous systems and may have an increased risk of getting cancer. 

Haloacetic acids are byproducts formed as a result of disinfection. Some people who drink water containing high levels of haloacetic acids over many years may have an increased risk of getting cancer.  

Radionuclides are unstable forms of elements that break down over time and release radiation. Some people who drink water containing levels of radionuclides above the MCL may have an increased risk of having kidney damage or getting cancer. 

Volatile organic chemicals (VOCs) are a variety of compounds composed primarily of carbon and hydrogen. They are used as solvents, degreasers, cleaning solutions, dry cleaning fluids and components of pesticides and plastics. Some people who drink water containing levels of VOCs above the MCL may have an increased risk of having organ damage, cancer or blood and nervous system disorders.

Public Information

The majority of water testing shows that Ohio's drinking water meets standards. When water does not meet a standard, the public water system is required to inform its consumers of the results. Public notification is required to include a clear and understandable explanation of the nature of the violation, its potential adverse health effects, steps that the public water system is taking to correct the violation and the possibility for the need to obtain alternative water supplies during the violation. Notification is required within 24 hours for acute contaminants and within 30 days for chronic contaminants.

Additionally, all community public water systems are required to prepare a Consumer Confidence Report (CCR) annually and distribute the report to their customers. The reports contain information on the community's drinking water, including the source of the water, the contaminants detected, the likely sources of detected contaminants, the health effects of contaminants when violations occur and the availability of source water assessments.

Finally, Ohio EPA’s Drinking Water Use Advisories page is available to help make water testing results for health-related contaminants more accessible to the public.

Additional Resources Include:

Reduction of Lead in Drinking Water Act - FAQs


A list of frequently asked questions is now available to assist manufacturers, retailers, regulators and the general public in complying with and understanding the requirements of the Reduction of Lead in Drinking Water Act. The FAQs address the definition of lead free, the effective date, calculating lead content, third-party certification, product labeling, repair and replacement parts and exemptions.

Electronic Drinking Water Reporting (eDWR) and Paper Forms

Results of water samples are reported to Ohio EPA by public water systems and certified laboratories to demonstrate that the water meets health based standards. The Division of Drinking and Ground Waters has developed the electronic Drinking Water Reports (eDWR) program to assist in the reporting process. This program can be accessed through the Ohio EPA eBusiness Center, which is a secure portal for online business services. Please visit the eDWR web page for more information on reporting forms, submitting data and getting started with eDWR and the eBusiness Center. 

Please note that the eDWR web page also includes various paper forms related to lead and copper, LT-2, chemical SSRs, microbiological SSRs, etc. 

Join one of DDAGW's electronic mailing lists to receive updates on electronic reporting.