Microbial water quality investigation through flow cytometry fingerprinting: from source to tap

Area of Science:

• Environmental microbiology
• Water quality analysis
• Analytical chemistry

Background:

• Traditional microbiological methods struggle with the complexity of drinking water bacterial communities.
• Ensuring drinking water quality is vital for public health and regulatory compliance.
• Microbial event detection is critical for maintaining safe water supplies.

Purpose of the Study:

• To evaluate the effectiveness of flow cytometry (FCM) fingerprints for microbial event detection in drinking water.
• To investigate the dynamics of bacterial communities during water treatment and in service reservoirs over one year.
• To assess the utility of FCM data for identifying operational issues and water quality deviations.

Main Methods:

• Daily interstage monitoring and flow cytometry (FCM) analysis were conducted over a 12-month period.
• Chlorine concentration contact time was analyzed for its impact on microbial reduction.
• Bray-Curtis dissimilarity index was used to quantify bacterial fingerprint diversity.

Main Results:

• FCM fingerprints showed significant deviations during operational disruptions but did not directly correlate with indicator organisms in tap water.
• Bacterial fingerprint diversity, measured by Bray-Curtis dissimilarity, indicated potentially poor microbial water quality.
• Chlorinated water background signals differentiated water sources and could characterize breakthrough events.
• Groundwater sources with simpler treatment showed higher indicator organism occurrence than surface water sources.

Conclusions:

• Flow cytometry (FCM) offers a valuable tool for real-time microbial event detection in drinking water treatment.
• Bacterial community diversity analysis using FCM can serve as an early warning for water quality degradation.
• Effective disinfection is crucial even for low-risk water sources, and statistical interpretation of FCM data aids decision-making.