Novel real-time or near real-time monitoring technologies and methods that can be utilized to monitor the performance of water reuse treatment systems (for both potable and non-potable water) and allow for rapid detection of upsets to a system and related water quality issues. The ability to detect such issues in a time frame measured in minutes rather than hours or days can allow for rapid responses from facility operators to ensure the protection of public health. Ideally technologies would have potential for robust data management capabilities to support the collection and utilization of the large amount of data collected while providing operators with sufficient information to utilize such data in a meaningful way. Monitoring technologies could target quantification of specific chemical or microbial contaminants that provide an accurate indication of system performance or utilize surrogate parameters to evaluate treatment system performance in way that can be correlated with the removal or inactivation of specific contaminants. Chemicals of interest can include regulated chemicals or other emerging compounds of concern including disinfection byproducts. Microbial contaminants of concern include pathogenic bacteria, viruses, and protozoa.