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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.

LOW PRICES and FAST SHIPPING SINCE 1999 !

99.5% Of All Items In Stock For Same Day Shipping!

Filter Direct Water Filters ®

Filter Direct Water Filters ®

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

Filter Direct RO-316

Filter Direct RO-435

Filter Direct RO-535

Filter Direct RO-316 Reverse Osmosis Water Filters
Filter Direct RO-316 Reverse ...

Filter Direct RO-316 Under Counter Reverse Osmosis Drinking Water System Compatible Replacement Water Filters, Reverse Osmosis Membranes, DIY Service Parts and Maintenance HELP Guides Low prices and fast shipping online since 1999. Millions sold. Quantity discounts.

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Filter Direct RO-435 Reverse Osmosis System Water Filters
Filter Direct RO-435 Reverse ...

Filter Direct RO-435 Compatible Replacement Water Filters and Reverse Osmosis Membranes. Low prices and fast shipping online since 1999. Quantity discounts. Huge inventory. Millions sold. HELP Guides.

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Filter Direct RO-535 Reverse Osmosis System Water Filters
Filter Direct RO-535 Reverse ...

Filter Direct RO-535 5 Stage Under Counter Reverse Osmosis Drinking Water System Compatible Replacement Water Filters, Reverse Osmosis Membranes, DIY Service Parts and Maintenance HELP Guides

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

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* FilterDirect ® is the registered trademark of FilterDirect, the manufacturer of FilterDirect ® 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 ® 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 ® under counter reverse osmosis drinking water equipment.
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  1. Filter Direct RO-316 Reverse Osmosis Water Filters
  2. Filter Direct RO-435 Reverse Osmosis System Water Filters
  3. Filter Direct RO-535 Reverse Osmosis System Water Filters

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