Roughing filters are used for the separation of solid particles. Similar to slow sand filters, they rely on natural water treatment processes. In Europe, roughing filters are applied in combination with slow sand filters for the artificial recharge of groundwater whereas in developing countries, the filter combination is used in rural water treatment plants. Since the roughing filter technology has been greatly developed over the last 10 years, an international workshop was held in Zurich last year to enhance the information exchange. The roughing filter technology will be presented hereafter in a somewhat larger context with a few selected papers and a summary of the practical field experience.