Ordinary sources, like databases and general-pupose document collections, seems to be insufficient and inadequate to scale the needs and the requirements of the new generation of warehouses: thematic data warehouses. Knowing that more and more online thematic data is available, the web can be considered as a useful data source for populating thematic data warehouses. To do so, the warehouse data supplier must be able to filter the heterogeneous web content to keep only the documents corresponding to the warehouse topic. Therefore, building efficient automatic tools to characterize web documents dealing with a given thematic is essential to challenge the warehouse data acquisition issue. In this paper, we present our filtering approach implemented in an automatic tool called “eDot-Filter”. This tool is used to filter crawled documents to keep only the documents dealing with food risk. These documents are then stored in a thematic warehouse called “eDot”. Our filtering approach is based on “WeQueL”, a declarative web query langage that improves the expressive power of keyword-based queries.