U.S. EPA and Ohio EPA use a multiple barrier approach to defend against waterborne pathogens and chemical contaminants in drinking water. Protection against contaminants occurs at each step from source to tap, beginning in the watershed or aquifer recharge area, continuing at the treatment facility and extending through the distribution system.
Source Water Selection and Protection
Selection of the best source of water available is an important step in protecting against contamination. For surface water sources, this means locating and constructing water intakes to ensure little or no contamination. For ground water sources, this means constructing wells in appropriate locations, at appropriate depths and with approved construction methods (e.g., casing and grouting).
Source Water Assessment and Protection helps public waters systems understand where the drinking water comes from, how contaminants can get into the water supply and how to protect the water from contamination at the source. Ohio EPA completes source water assessments for every public water system. Each assessment includes:
- Delineating (or mapping) the source water assessment area;
- Conducting an inventory of potential sources of contamination in the delineated area;
- Determining the susceptibility of the water supply to those contamination sources; and
- Releasing the results of the determinations to the public.
The results of the assessment can be used to organize, develop and implement a source water protection plan.
System Design and Operation
Plan approval ensures that the system is well-engineered and constructed to reliably protect finished water from contamination. The type of treatment required depends on the physical, microbiological and chemical characteristics and the types of contaminants present in the source water. Also, storage facilities and distribution systems must have full circulation and avoid stagnant water conditions that might facilitate contamination.
Sanitary surveys are routine inspections of public water systems to ensure proper construction and operation. The purpose of the sanitary survey is to evaluate and document the capabilities of a water system’s sources, treatment, storage, distribution network, operation and maintenance and overall management to continually provide safe drinking water and to identify any deficiencies that might adversely impact a public water system’s ability to meet applicable regulations and provide a safe reliable water supply.
Competent operating personnel are vitally important to the safety of drinking water. Ohio EPA's Operator Certification rules require that certain public water systems have a certified operator that is qualified to operate the system. To become a certified operator, a person must meet educational and experience requirements, pass an exam and maintain their certification through continuing education (contact hours).
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.
Contaminants that may be tested for include:
- 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 Contaminant Information section of the 'Monitoring' tab.
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:
Action level: The concentration of lead or copper in water that may trigger requirements for corrosion control, source water treatment, lead service line replacement and public education. Compliance with an action level is based on multiple samples.
Human consumption: The ingestion or absorption of water or water vapor as the result of drinking, cooking, dishwashing, hand washing, bathing, showering or oral hygiene.
Maximum contaminant level (MCL): The maximum allowable level of a contaminant in public drinking water. Most often, compliance with an MCL is based on an average of multiple samples.
Maximum residual disinfectant level (MRDL): The maximum allowable level of disinfectant in public drinking water. Most often, compliance with an MRDL is based on an average of multiple samples.
Milligrams per liter (mg/L): Milligrams of contaminant per liter of drinking water.
Public water system (PWS): A system that provides water for human consumption to an average of at least 25 individuals daily at least 60 days out of the year, or has at least 15 service connections. This includes water used for drinking, food preparation, bathing, showering, tooth-brushing and dishwashing.
Community PWS: Serves at least 15 service connections used by year-round residents or regularly serves at least 25 year-round residents. Examples include cities, mobile home parks and nursing homes.
Non-transient, non-community PWS: Regularly serves at least 25 of the same persons over six months per year. Examples include schools and businesses.
Transient, non-community PWS: Regularly serves at least 25 different persons over 60 days per year. Examples include restaurants and gas stations.
Public water system identification number (PWSID): A unique identifier for each public water system.
Secondary maximum contaminant level (SMCL): The advisable maximum allowable level of a contaminant in public drinking water.
Treatment technique: A method for treating water to achieve acceptable levels of contaminants in lieu of establishing a maximum contaminant level.
See Ohio Administrative Code (OAC) 3745-81-01 for additional definitions.