MINNETONKA, Minn., December 11, 2002--Osmonics (NYSE: OSM) announced today that it has launched a new version of a previous product, the AutoSDI or Automated Silt Density Index (SDI), to predict membrane-fouling potential for reverse osmosis (RO) installations. The AutoSDI Test Unit eliminates the need for stopwatches, graduated cylinders, wet notes, calculators and tedious labor. In approximately fifteen minutes after the push of one button, users will know a relative value for the amount of suspended matter in feedwater streams.

According to business manager, Andrew Zaske, "SDI testing is commonly used as an early alert to ensure that particulates in feedwater do not plug the pores in RO membrane elements. It is recommended that an SDI measurement be taken once a week at RO installations. The AutoSDI allows users to perform this measurement quickly, accurately and consistently without having to do complicated calculations."

Osmonics has taken the previous AutoSDI product and improved the design. The mechanical pieces are similar but the electronics have all significantly changed. Most importantly, the AutoSDI unit now can be calibrated in the field. The unit will run continuously and then display a five, ten and fifteen minute SDI reading at the conclusion of its test.

For further information on Osmonics' technology, call 800-766-2599 or 952-933-2277; write to Osmonics at 5951 Clearwater Drive, Minnetonka, MN 55343-8995; or visit the company's web site at www.osmonics.com.

Osmonics is a leading manufacturer and worldwide marketer of high-technology water purification and fluid filtration, fluid separation and fluid handling equipment, as well as the replaceable components used in purification, filtration, and separation equipment. These products are used by a broad range of industrial, commercial, household and institutional customers. Osmonics is traded on the New York Stock Exchange under the symbol OSM.