Large selection of replacement water filters, reverse osmosis membranes, testing kits and water filter system repair parts. From one water filter or membrane to case quantity discounts.

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Filter Direct Water Filters ®

Filter Direct Water Filters ®

 

Filter Direct Under Counter Reverse Osmosis Drinking Water System Compatible Replacement Water Filters, Reverse Osmosis Membranes, Faucets, tanks, valves, connectors, DIY Maintenance Parts and Service HELP Guides

Filter Direct RO-316 Replacement Water Filters

Filter Direct RO-435 Replacement Water Filters

Filter Direct RO-535 Replacement Water Filters

Easy TDS Membrane Performance Calculator
See If It is Time To Replace Your Membrane

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.





* FilterDirect RO-316, RO-435 and RO-535 ® is the registered trademark of FilterDirect, the manufacturer of FilterDirect RO-316, RO-435 and RO-535 ® brand water treatment equipment.  The replacement filters and membranes listed above are not manufactured or endorsed by FilterDirect.  Rather, these filters and membranes are manufactured by other companies.  While these filters and membranes are compatible for use in FilterDirect RO-316, RO-435 and RO-535 ® 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 FilterDirect RO-316, RO-435 and RO-535 ® under counter reverse osmosis drinking water equipment.