The EZ Series Toxicity analyzer is able to detect and measure wastewater streams that present an acute or chronic toxicity to the biomass of a treatment plant. This allows operators to take corrective measures to protect the viability of the waste water treatment plant, e.g. by storing the toxic water in a buffer tank. With a response time of 15 minutes, toxic compounds present in the wastewater can be detected in an early stage by the Toxicity analyzer. The on-line analyzer thus functions as an early warning system and, indirectly, as a continuous assessment of a healthy respiration rate of the biomass.