This document specifies a method for the determination of drainability of flocculated sludge. It 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 origins.