The ceramic silver-impregnated pot filter (CSF) is a low-cost drinking water treatment system currently produced in many factories worldwide. CSFs from three production locations - Cambodia, Ghana and Nicaragua – were tested for effective pore size, removal efficiency of microorganisms, and water production [1,2].

Effective pores of the CSFs were measured with a mean of 40 micrometer, which is larger than many pathogenic microorganisms. Nevertheless, they successfully removed total coliforms and sulphite reducing Clostridium spores. High concentrations of Escherichia coli K12 were also removed, with log(10) reduction values consistently higher than 2. MS2 bacteriophages were only partially removed from the water, with significantly better results for filters without an impregnation of colloidal silver. It was concluded that the indicator organisms were removed by other mechanisms than absolute screening, namely mechanism of sedimentation, diffusion, inertia, turbulence and adsorption.

The main deficiency of the CSFs proved to be the low water production; after 12 weeks of use all filter discharges were below 0.5 litres per hour, which was insufficient to provide drinking water for a family.

[1] Halem, D. van … [et al.] (2007). Ceramic silver-impregnated pot filters for household drinking water treatment in developing countries. Water science & technology: water supply ; vol. 7, no. 5-6 ; p. 9–17. Download pdf (pay-per-view)

[2] Halem, D. van (2006). Ceramic silver impregnated pot filters for household drinking water treatment in developing countries. M.Sc. thesis. Delft, The Netherlands, Sanitary Engineering Section, Dept. of Water Management, Faculty of Civil Engineering, Delft University of Technology. PDF file (2.8 MB)

Related web sites: Potters Without Borders Canada ; Potters for Peace ; Get Them Ceramic Water Purifiers ; Practica Foundation – Ceramic water filter

Contact: Ir. Doris van Halem, TU Delft, The Netherlands, D.vanHalem@TUDelft.nl

Tags: water quality