This Technical Report specifies procedures for validating characterization methods for physical properties of sludge. This Technical Report is applicable to sludge and sludge suspensions from: - storm water handling; - urban wastewater collecting systems; - urban wastewater treatment plants; - treating industrial wastewater similar to urban wastewater (as defined in Directive 91/271/EEC); - water supply treatment plants. This method is also applicable to sludge suspensions from other origin.