Epa Water Pollutant Allowances: Understanding The Limits

The US Environmental Protection Agency (EPA) regulates water pollutants through legally enforceable standards and treatment techniques that apply to public water systems. These regulations, known as National Primary Drinking Water Regulations (NPDWR) or primary standards, aim to protect public health by limiting the levels of contaminants in drinking water. The EPA sets legal limits for over 90 contaminants, including arsenic, lead, copper, and fluoride, to protect human health and ensure water quality. The EPA also establishes water-testing schedules, methods, and monitoring requirements for water systems to follow. In addition to NPDWRs, the EPA also recommends non-enforceable secondary standards, known as National Secondary Drinking Water Regulations (NSDWR), which address cosmetic and aesthetic effects of contaminants. The EPA's efforts to ensure safe drinking water involve multiple barriers, including the Safe Drinking Water Act (SDWA) and the development of contaminant lists, such as the Toxic Pollutant List and the Priority Pollutant List, to address the presence of toxic chemicals in waterways.

National Primary Drinking Water Regulations (NPDWR)

The National Primary Drinking Water Regulations (NPDWR) are a set of legally enforceable primary standards and treatment techniques that apply to public water systems in the United States. These regulations are designed to protect public health by limiting the levels of contaminants in drinking water and ensuring its safety for consumption.

The NPDWR sets specific limits on various contaminants, including:

• Lead and copper: Water systems must employ treatment techniques to control the corrosiveness of their water. If more than 10% of tap water samples exceed the action level, additional measures must be taken. The action level for copper is set at 1.3 mg/L, while for lead, it is 0.010 mg/L.
• Acrylamide and epichlorohydrin: Water systems must certify that the combination of dose and monomer level does not exceed the specified limits. Acrylamide should not exceed 0.05% dosed at 1 mg/L, while epichlorohydrin should not exceed 0.01% dosed at 20 mg/L.
• Turbidity: The cloudiness of water must not exceed specific limits, depending on the filtration method used. For conventional or direct filtration, turbidity must not go higher than 1 Nephelometric Turbidity Unit (NTU), and samples must be less than or equal to 0.3 NTUs in at least 95% of the samples in any month.
• Cryptosporidium and Giardia lamblia: Unfiltered systems must include provisions for controlling these contaminants in their watershed. For Giardia lamblia, a 99.9% removal/inactivation rate is required.
• Maximum Contaminant Level (MCL): This is the highest level of a contaminant permitted in drinking water and is set based on the Maximum Contaminant Level Goal (MCLG), which represents the level below which there is no known or expected risk to health. MCLs take into account the best available treatment technology and cost considerations.
• Maximum Residual Disinfectant Level (MRDL): This is the highest level of disinfectant permitted in drinking water, as there is evidence that disinfectants are necessary for controlling microbial contaminants.

The Environmental Protection Agency (EPA) sets legal limits on over 90 contaminants in drinking water, ensuring that these limits are achievable by water systems using the best available technology. The Safe Drinking Water Act (SDWA) gives individual states the authority to establish and enforce their own drinking water standards, as long as they meet or exceed the EPA's national standards.

Treatment Techniques (TT)

The US Environmental Protection Agency (EPA) enforces Treatment Techniques (TT) as part of its National Primary Drinking Water Regulations (NPDWR). These are required processes intended to reduce the level of contaminants in drinking water.

When there is no reliable or economically and technically feasible method to measure a contaminant at concentrations that indicate there is not a public health concern, the EPA sets a treatment technique rather than a maximum contaminant level (MCL). A TT is an enforceable procedure or level of technological performance that public water systems must follow to ensure control of a contaminant. The EPA determines the feasible MCL or TT, defined by the Safe Drinking Water Act (SDWA) as the level that may be achieved with the best available technology or treatment approaches.

The EPA regulates over 90 drinking water contaminants, and the legal limit for each contaminant reflects the level that protects human health and that water systems can achieve using the best available technology. The EPA also sets water-testing schedules and methods that water systems must follow.

Some specific examples of TTs include:

• Corrosiveness control for lead and copper. If more than 10% of tap water samples exceed the action level, water systems must take additional steps. The action level for copper is 1.3 mg/L, and for lead, it is 0.010 mg/L.
• Removal/inactivation of Giardia lamblia: 99.9% removal/inactivation required.
• Turbidity control: For systems using conventional or direct filtration, turbidity (cloudiness of water) cannot exceed 1 Nephelometric Turbidity Unit (NTU) at any time, and samples must be less than or equal to 0.3 NTUs in at least 95% of the samples in any month.

Maximum Contaminant Level Goals (MCLG)

The Maximum Contaminant Level Goal (MCLG) is the maximum level of a contaminant in drinking water that is considered safe for human health. It is a non-enforceable public health goal, which means that it is a target level rather than a legally binding limit. The MCLG is determined by the US Environmental Protection Agency (EPA) based on health effects data and allows for a margin of safety. The goal is to ensure that there are no known or anticipated adverse health effects from contaminants in drinking water.

The MCLG is an important concept in the National Primary Drinking Water Regulations (NPDWR), which are legally enforceable primary standards and treatment techniques that apply to public water systems. These regulations are designed to protect public health by limiting the levels of contaminants in drinking water. The NPDWR includes both MCLGs and Maximum Contaminant Levels (MCLs). While MCLGs are non-enforceable goals, MCLs are legally enforceable standards that set the highest permissible level of a contaminant in drinking water.

The process of setting MCLGs involves reviewing health effects data and considering the potential adverse health risks to sensitive subpopulations. For microbial contaminants and chemical contaminants that are carcinogens, the EPA sets the MCLG at zero, as even small amounts can cause adverse health effects. In other cases, the MCLG may be set at a level where there is no known or expected risk to health, allowing for a margin of safety.

It is important to note that MCLGs are not always achievable by water systems due to technological limitations. In such cases, the EPA sets a "treatment technique" instead of an MCL. Treatment techniques are enforceable procedures or levels of technological performance that public water systems must follow to ensure the control of contaminants. Additionally, the EPA also establishes water-testing schedules and methods that water systems must adhere to.

Maximum Residual Disinfectant Levels (MRDL)

The Maximum Residual Disinfectant Level (MRDL) is the highest level of disinfectant that is allowed in drinking water. MRDL is set at 4.0 mg/L, which is based on a running annual average of all samples in the distribution system. The Environmental Protection Agency (EPA) set this limit due to the increased risk of cancer for people who drink water with very high levels of free or total chlorine over an extended period.

The MRDL is a legally enforceable standard that applies to public water systems. It is a required process intended to reduce the level of disinfectant in drinking water. The level is usually measured in milligrams per liter (mg/L) unless otherwise noted. Milligrams per liter are equivalent to parts per million (PPM).

The EPA's surface water treatment rules require systems using surface water or groundwater under the direct influence of surface water to meet specific criteria for avoiding filtration. This ensures that contaminants such as Cryptosporidium and Giardia lamblia are controlled at acceptable levels.

Public water systems must regularly monitor and record disinfectant levels in their distribution systems. This is done through the Disinfectant Level Quarterly Operating Report (DLQOR), which is reported to the Texas Commission on Environmental Quality (TCEQ) every quarter. Systems are required to keep records of disinfectant levels for at least three years and make them available to TCEQ staff during routine inspections and upon request.

The EPA sets legal limits on over 90 contaminants in drinking water, reflecting levels that protect human health and that water systems can achieve using the best available technology. These limits are reviewed every five years, largely based on the Contaminant Candidate List.

Health-Based Water Concentration (HBWC)

The US Environmental Protection Agency (EPA) sets legal limits on over 90 contaminants in drinking water. The National Primary Drinking Water Regulations (NPDWRs) are legally enforceable primary standards and treatment techniques that apply to public water systems. These standards protect public health by limiting the levels of contaminants in drinking water.

The EPA's goal is to maintain drinking water quality and protect public health. To achieve this, the agency sets Maximum Contaminant Level Goals (MCLGs) and Maximum Contaminant Levels (MCLs). MCLGs are health-based goals that represent the level of a contaminant in drinking water below which no known or expected risk to health exists. They allow for a margin of safety and are non-enforceable. On the other hand, MCLs are the highest permissible levels of contaminants in drinking water and are enforceable standards.

The EPA also establishes Treatment Techniques (TTs), which are required processes intended to reduce contaminant levels. Additionally, the agency sets Maximum Residual Disinfectant Levels (MRDLs), which represent the highest allowable level of disinfectants in drinking water. The addition of disinfectants is crucial for controlling microbial contaminants.

The Safe Drinking Water Act (SDWA) gives states the authority to set their own drinking water standards, provided they are at least as stringent as the EPA's national standards. The EPA's Unregulated Contaminant Monitoring Program collects data on contaminants without health-based standards, and the agency regularly reviews the list of contaminants to ensure water safety.

Furthermore, the EPA provides Drinking Water Health Advisories (HAs), which serve as informational resources for water systems and officials during emergencies or contamination events. These HAs offer guidance on health effects, analytical methods, and treatment technologies. While not legally enforceable, they help states, tribes, and local governments protect public health and determine necessary actions.

Overall, the EPA's regulations, including the concept of HBWC, play a vital role in safeguarding drinking water quality and protecting the health of communities across the nation.

Frequently asked questions