What does a high MPN (Most Probable Number) indicate in water testing?

A high Most Probable Number (MPN) in water testing specifically indicates the presence of high levels of coliform bacteria. MPN is a statistical method used to estimate the number of viable microorganisms in a sample, particularly in water. Coliform bacteria, which are often utilized as indicators of water quality, signify potential contamination by fecal material or other harmful pathogens. Therefore, when MPN results show elevated levels, it suggests that the water may pose health risks due to bacterial contamination, making it unsuitable for drinking and recreational uses.

The other options relate to different types of contaminants or conditions in water that are not directly indicated by MPN testing. High chemical levels, heavy metals, and turbidity require different testing methods and parameters to assess and measure their presence, highlighting why the MPN specifically points to coliform bacteria.