Easy TDS Membrane Performance Calculator

See If It is Time To Replace Your Membrane

Feed Water TDS

RO Water TDS

Submit

Simply enter your Feed Water TDS and RO Water TDS into the boxes above and click "Submit". The percentage of TDS Rejection will be displayed. We normally recommend membrane replacement once you drop below 75%. This may vary in areas with high TDS in the feed water.

See our selection of TDS meters under Water Tests

Be sure to check our Parts Department for important parts such as TDS Testers For Reverse Osmosis Membranes, Replacement Tanks, O-rings , Filter Housing Wrenches, Faucets, Pumps, Fittings, UV Systems and more parts for your reverse osmosis pure water filtration system.   View maintenance and servicing tips online at our Installation & Trouble shooting Guide.

* Dow Filmtec ® is the registered trademark of Dow, the manufacturer of Dow Filmtec ® brand water treatment equipment. The replacement filters and membranes listed above are not manufactured or endorsed by Dow Filmtec. Rather, these filters and membranes are manufactured by other companies. While these filters and membranes are compatible for use in Dow Filmtec ® brand water treatment equipment, we make no representation as to whether using these filters and membranes is consistent with the warranty and specifications applicable to Dow Filmtec ® equipment.