According to the Centers for Disease Control and Prevention, which has conducted studies on E. coli and chlorine, “both pathogenic and nonpathogenic strains (of E. coli) were significantly reduced within 1 minute of exposure to free chlorine.

Results indicate that chlorine levels typically maintained in water systems are sufficient to inactivate these organisms.”

So, to address the question of whether the children in the accompanying story might have gotten sick at the Riverside Sprayground: While E. coli is generally not chlorine-resistant, certain factors can contribute to its presence even in chlorinated environments.

Here are a few possibilities: 1. Inadequate Contact Time: Even if chlorine levels are within the recommended range, the chlorine might not have had enough contact time with the bacteria to kill all of it. This can happen if the water is circulating too quickly or if there are dead spots where the water is not properly mixed.

2. Biofilms: Bacteria can form biofilms on surfaces within the splash pad system. These biofilms can protect bacteria, including E. coli, from being exposed to chlorine. Biofilms can form on surfaces that are not regularly cleaned or disinfected.

3. High Organic Load: A high level of organic matter (like leaves, dirt, or body fluids) in the water can consume chlorine and reduce its effectiveness.

This can allow bacteria to survive even if chlorine levels are initially adequate.

4. Intermittent Treatment: If the chlorination system is not consistently maintaining the proper levels of chlorine, there could be periods when the water is under-treated, allowing bacteria to survive and multiply.

5. Samp l ing Er r o r s o r Contamination: The way water samples are collected and handled can affect test results. If there is contamination during sampling or testing, it could lead to false positives for bacterial presence.

Given these factors, while it is unlikely that the E. coli found in the splash pad is chlorineresistant, it is possible that the water treatment protocols are not being followed as rigorously as the Riverside facility reported, or there are other issues in the system that are allowing bacteria to persist.