This TIP describes the methods and procedure for the measurement of press felt permeability to water. The method is suitable for the evaluation of felts on the run, without interrupting the operation of the paper machine. This technique could be used to follow changes in felt permeability which occur during felt life. The method also can be used to measure the cross direction (CD) permeability profile and machine direction permeability variation to identify localized areas of low permeability.