In case of special requirement for Purified Water quality, e.g. Highly Purified Water, or Purified Water with low endotoxyn content. In this case, especially if a PW generation system based on RO+EDI is installed, a final treatment of the produced PW is necessary to reduce the content of endotoxyn. In order to obtain this result, Stilmas may install an UF section composed by sanitary feed pump and ultrafiltration module downstream the electro-deionizer, granting a very low final endotoxyn content. The UF membranes can be sanitized chemically or by hot water.