A geotextile filtration testing method termed a hanging‐bag test was used to treat dairy lagoon sludge, swine lagoon sludge, liquid dairy manure, and liquid swine manure. Hanging‐bag performance was evaluated by: (1) determining solids and plant nutrient mass retention efficiencies, (2) quantifying the overall volume reduction, and (3) characterizing the dewatered manure or liquid dairy manure, geotextile filtration reduced the total influent volume to less than 1%, concentrated the solids and nutrients in the dewatered material 16 to 21 times greater than the influent, and retained 38.4% of total solids, 25.8% of total ammoniacal nitrogen, and 45.0% of total phosphorous, making this an effective liquid‐solid separation technique.