The Filter Judge can benefit the operator of a facility that uses gravity filter media for the filtration of liquids. The operator can quickly take an accurate sample of the media during a backwash cycle without taking the filter out of operation. There is no need to send a worker down into the filter to dig a hole in the media. Downtime is reduced, and the hazards of sending a worker into the filter (confined space) are eliminated. Furthermore, multiple samples can be taken in a short period of time.