Are you concerned about the presence of dichloroacetic acid and trichloroacetic acid in your drinking water? These substances, often referred to as disinfection byproducts (DBPs), are formed when chlorine and other disinfectants react with natural organic matter during water treatment. Understanding where these compounds are found, why they are regulated, and how to access information about them is crucial for ensuring water safety.
Dichloroacetic acid and trichloroacetic acid belong to a group of chemicals known as Haloacetic Acids (HAA5). These are not intentionally added to your water supply but are created as a consequence of the disinfection process, which is essential for killing harmful pathogens. While disinfection is vital for public health, the resulting DBPs are monitored due to potential long-term health risks.
What are Haloacetic Acids and Why Dichloroacetic & Trichloroacetic Acid Matter?
Haloacetic acids (HAAs) are a class of disinfection byproducts that form when chlorine or other chemical disinfectants are used to treat drinking water. Among the various HAAs, dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) are significant due to their prevalence and potential health effects.
- Dichloroacetic acid and trichloroacetic acid formation: These acids arise from the reaction between disinfectants and naturally occurring organic matter present in source water. This organic matter can include decaying vegetation and soil runoff.
- Regulation: Recognizing the potential health risks, regulatory bodies like the Environmental Protection Agency (EPA) in the United States and state agencies like the Texas Commission on Environmental Quality (TCEQ) set limits for HAAs in drinking water.
Health Concerns and Regulatory Limits for Dichloroacetic and Trichloroacetic Acid
Prolonged exposure to high levels of certain DBPs, including dichloroacetic acid and trichloroacetic acid, raises health concerns. The EPA has established Maximum Contaminant Level Goals (MCLGs) and Maximum Contaminant Levels (MCLs) to regulate these substances in public drinking water systems.
| Contaminant | MCLG (mg/L) | MCL (mg/L) | Potential Health Effects from Long-Term Exposure Above the MCL |
|---|---|---|---|
| Bromate | zero | 0.010 | Increased risk of cancer |
| Chlorite | 0.8 | 1.0 | Anemia; infants and young children: nervous system effects |
| Haloacetic acids (HAA5) | N/A* | 0.060 | Increased risk of cancer |
| Total Trihalomethanes (TTHMs) | N/A* | 0.080 | Liver, kidney or central nervous system problems; increased risk of cancer |
*Note: While there is no collective MCLG for HAA5 and TTHMs, individual MCLGs exist for some components, including dichloroacetic acid (zero) and trichloroacetic acid (0.3 mg/L).
These regulations are in place to minimize potential health risks, primarily the increased risk of cancer associated with long-term exposure to HAAs above the MCL. It’s important to note that the MCLs are set significantly below levels where health effects have been observed, providing a margin of safety.
Where to Find Dichloroacetic and Trichloroacetic Acid: In Your Drinking Water
Dichloroacetic acid and trichloroacetic acid, as components of HAA5, are primarily found in treated drinking water systems that utilize chlorination or similar disinfection methods. They are not naturally occurring contaminants in source water but are byproducts of the necessary disinfection process.
The levels of these DBPs can vary depending on factors such as:
- Source water quality: Higher levels of natural organic matter in the raw water can lead to increased DBP formation.
- Disinfection practices: The type and amount of disinfectant used, as well as the disinfection process itself, influence DBP formation.
- Water age: DBP levels can sometimes increase as water travels through distribution systems and ages.
Public water systems are mandated to monitor and control DBP levels to comply with regulatory standards.
Accessing Information: Finding DBP Levels in Your Water
If you are concerned about the levels of dichloroacetic acid and trichloroacetic acid or other DBPs in your drinking water, there are several avenues to access this information:
- Consumer Confidence Reports (CCR): Community water systems are required to provide annual water quality reports, also known as CCRs, to their customers. These reports summarize the detected contaminants, including HAAs and TTHMs, and compare them to the MCLs. Your CCR is a valuable resource for understanding your local water quality.
- Drinking Water Watch: Many states have online databases, like Texas Drinking Water Watch, which provide public access to drinking water quality data. These databases often include sample results for DBPs, monitoring schedules, and any violations. You can typically search by water system name or location to find relevant information.
- Contacting Your Water Supplier: Your local water utility is the most direct source of information about your drinking water quality. They can provide specific data on DBP levels, treatment processes, and compliance with regulations. Water systems often have dedicated customer service departments to address water quality inquiries.
You can use online tools like Drinking Water Watch to access DBP sample results and sample schedules related to your water system.
To find DBP sample results within Drinking Water Watch, you can look for analyte codes such as:
- 2456: Total Haloacetic Acids (HAA5)
While individual results for dichloroacetic acid and trichloroacetic acid may not always be explicitly listed separately in summary reports, the total HAA5 level provides an indicator of the overall Haloacetic acid concentration, which includes these two compounds.
Understanding Compliance and Addressing Violations
Water systems must adhere to the MCL for HAA5 (0.060 mg/L, Locational Running Annual Average – LRAA) to avoid violations. The LRAA is calculated at each monitoring location by averaging the HAA5 results from the four most recent quarters.
LRAA Formula: (Q1 + Q2 + Q3 + Q4) / 4 = LRAA
- MCL Violation: If the LRAA for HAA5 exceeds 0.060 mg/L at any monitoring location, it constitutes an MCL violation.
- Monitoring and Reporting Violation: Failure to collect required samples or report results also results in a violation.
- Public Notice Violation: Water systems are legally obligated to notify their customers if a violation occurs. This includes providing public notice about the violation, potential health effects, and corrective actions.
In case of a violation, water systems are required to take corrective actions to reduce DBP levels and ensure compliance. This might involve optimizing treatment processes, changing disinfectants, or implementing other strategies to minimize DBP formation.
Unregulated DBPs and Future Considerations
It’s worth noting that regulatory agencies continuously evaluate other DBPs for potential regulation under rules like the Unregulated Contaminant Monitoring Rule (UCMR). This ongoing monitoring and research ensure that drinking water standards remain protective of public health as scientific knowledge evolves.
Conclusion: Staying Informed About Your Water Quality
Dichloroacetic acid and trichloroacetic acid are disinfection byproducts present in drinking water treated with chlorine and similar disinfectants. While regulations are in place to limit their levels and minimize potential health risks, staying informed about your water quality is essential. Utilize resources like Consumer Confidence Reports, online databases, and your water supplier to access information and ensure your drinking water meets safety standards. Understanding where to find information about these substances empowers you to make informed decisions about your water consumption and advocate for safe and high-quality drinking water in your community.
