This document specifies a method for the determination of the thickenability of sludge suspensions. This document is applicable to 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.