Disinfection Byproducts in Shawnee RWD#1: What Happened and How It's Being Resolved

Additional information regarding your District's non-compliance letter

Understanding Drinking Water Disinfection Byproducts and Our Commitment to Safe Water

Dear Valued Customers,

As part of our ongoing commitment to transparency and providing safe, high-quality drinking water, we want to address recent concerns regarding our compliance with the EPA's standards for disinfection byproducts (DBPs). While our water supplier has remained in compliance, our district has been out of compliance with the regulatory limits for DBPs. We’d like to explain why this has happened and assure you that your drinking water remains safe.

What Are Disinfection Byproducts?

Disinfection byproducts are compounds that form when disinfectants, such as chlorine, react with natural organic matter in the water. These byproducts, including trihalomethanes (THMs) and haloacetic acids (HAAs), are regulated by the EPA to protect public health. The compliance level is determined by a locational running annual average (LRAA) of quarterly test results.

Why Are We Out of Compliance?

While we purchase all our water from a neighboring city (City of Topeka) that remains in compliance with DBP regulations, one of our quarterly tests conducted by the Kansas Department of Health and Environment (KDHE) lab returned exceptionally high DBP levels. This single high result significantly skewed our locational running annual average (LRAA) above the regulatory limit. Since switching to a different certified laboratory, our subsequent test results have been much lower and below the regulatory threshold, highlighting our belief that the initial result was biased high due to laboratory testing variations.

Laboratory Testing Variations

Laboratory testing can yield different results due to differences in methods, equipment, and calibration standards. For example, the EPA’s Method 552.3 is commonly used to measure haloacetic acids (HAAs) in drinking water. This method involves a complex process that includes extracting HAAs from the water sample, using specialized chemicals and equipment to isolate the compounds, and analyzing them with precise instruments such as gas chromatographs. Because this process is highly technical, small variations in equipment calibration, chemical handling, or procedural steps can result in differences between the reported values and the actual levels. These testing tolerances are normal and can lead to some discrepancies between labs, even when analyzing identical water samples.

Why Do We Feel Changing Labs Is Appropriate in This Situation?

When we first received notice of non-compliance, we immediately took multiple steps to determine the cause. One of our first actions was to contact KDHE directly and request their assistance in resolving the issue. With support from KDHE's Division of Water Resources, numerous additional samples were collected from various points in our distribution system and sent to the KDHE lab for analysis. However, the results from these samples were highly inconsistent, with some returning values that seemed implausible.

To rule out human error during sample collection, we conducted another round of sampling, with multiple individuals collecting water from the same source at the same time. Despite the identical conditions, the test results were again inconsistent. To further investigate, we sent identical water samples to both KDHE's lab and a private lab we have trusted in the past. The private lab consistently reported lower HAA levels than KDHE's lab for the same water samples, although both results exceeded the compliance threshold.

We initially began using KDHE's lab because of its lower testing costs, but the discrepancies in results and subsequent compliance issues have negated any cost savings. Additionally, the private lab provides more detailed and consistent reports, which increases our confidence in their findings. Moving forward, we will return to utilizing the private lab for all required disinfection byproduct testing to ensure accurate and reliable data.

Is the Water Safe to Drink?

Yes, your water remains safe to drink. The EPA’s DBP limits include a substantial margin of safety, ensuring that short-term exceedances do not pose an immediate health risk. While we believe the actual DBP values over the past year are lower than those reported by KDHE's lab, we take these exceedances very seriously. We are working diligently to address the issue and ensure future compliance. Our district is also continuously evaluating and implementing improvements to guarantee the consistent quality and safety of your drinking water.

Our Commitment to You

We are committed to providing you with safe and reliable drinking water. If you have any questions or concerns, please do not hesitate to contact our office. Thank you for your understanding and continued trust as we work to resolve this issue.

Sincerely,

Justin Kramer
District Manager
Shawnee Cons. Rural Water District #1