A system for the determination of an electrical characteristic, in particular the streaming potential or zeta-potential, of a particles containing liquid in a measurement cycle, said system including: - a measurement apparatus which comprises: - a measuring conduit (2, 2a, 2b) for said liquid, - a first electrode and a second electrode spaced from each other along the measuring conduit, so that each electrode (4, 6) contacts said liquid in said measuring conduit during the measurement cycle, - a signal processing means connected to said first and second electrodes (4, 6) for the determination of the electrical characteristic of said liquid in said measurement cycle, - a particles retaining filter effective at a location in said measuring conduit during the measurement cycle, which particles retaining filter allows for the build up and retention of a plug of particles for said measurement cycle, - a controllable variable liquid flow means (40, 41)adapted to generate during said measurement cycle a controlled liquid flow variation across the plug of particles on said filter for the purpose of determination of said electrical characteristic of said liquid, characterized in that the system further comprises: - an intermittent filtering web feed mechanism (22, 25, 27), and - a roll of disposable filtering web or a zigzag folded continuous disposable filtering web, wherein the measurement apparatus has a path for the disposable filtering web that extends across the measuring conduit so that a portion of the web in said measuring conduit forms the particles retaining filter, and wherein the intermittent filtering web feed mechanism is adapted to advance said filtering web intermittently so that as to replace the portion of filtering web used as particles retaining filter in a measurement cycle for a clean and non-used portion of the filtering web for the next measurement cycle. - a measurement apparatus which comprises: - a measuring conduit (2, 2a, 2b) for said liquid, - a first electrode and a second electrode spaced from each other along the measuring conduit, so that each electrode (4, 6) contacts said liquid in said measuring conduit during the measurement cycle, - a signal processing means connected to said first and second electrodes (4, 6) for the determination of the electrical characteristic of said liquid in said measurement cycle, - a particles retaining filter effective at a location in said measuring conduit during the measurement cycle, which particles retaining filter allows for the build up and retention of a plug of particles for said measurement cycle, - a controllable variable liquid flow means (40, 41)adapted to generate during said measurement cycle a controlled liquid flow variation across the plug of particles on said filter for the purpose of determination of said electrical characteristic of said liquid, - a measuring conduit (2, 2a, 2b) for said liquid, - a first electrode and a second electrode spaced from each other along the measuring conduit, so that each electrode (4, 6) contacts said liquid in said measuring conduit during the measurement cycle, - a signal processing means connected to said first and second electrodes (4, 6) for the determination of the electrical characteristic of said liquid in said measurement cycle, - a particles retaining filter effective at a location in said measuring conduit during the measurement cycle, which particles retaining filter allows for the build up and retention of a plug of particles for said measurement cycle, - a controllable variable liquid flow means (40, 41)adapted to generate during said measurement cycle a controlled liquid flow variation across the plug of particles on said filter for the purpose of determination of said electrical characteristic of said liquid, - an intermittent filtering web feed mechanism (22, 25, 27), and - a roll of disposable filtering web or a zigzag folded continuous disposable filtering web, wherein the measurement apparatus has a path for the disposable filtering web that extends across the measuring conduit so that a portion of the web in said measuring conduit forms the particles retaining filter,