A filtration-free liquid sampling system may be used to extract particulate or debris-containing liquid samples that may otherwise plug a filter over its service life. For example, such a system may be used to extract liquid sample from an industrial textile washer to monitor and/or validate the quality of wash conditions within the washer. In some examples, the system includes a pump that creates a vacuum on a backstroke, drawing liquid into a sensor housing positioned between the pump and the washer. After holding the liquid in the sensor housing long enough to measure its properties, the pump can be driven in a reverse stroke to pressurize the contents in the sensor housing and force the liquid back into the washer. This vacuum fill/pressure purge can keep the sensor housing free of debris.