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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 PuroTwist "Q" Series Water Filters ®

PuroTwist "Q" Series Water Filters ®

PuroTwist ® Reverse Osmosis System Q Series Replacement Water Filter Cartridges, Reverse Osmosis RO Membranes, DIY Replacement Parts and HELP Guides.

PuroTwist PT000 Under Counter Filter System and PT3000 and PT4000 PuroTwist Reverse Osmosis Systems


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.

* PuroTwist is the registered trademark of PuroTwist, the manufacturer of PuroTwist brand of under counter drinking water system filtration equipment.  The replacement water filter cartridges, reverse osmosis membranes, water tanks, faucets and repair parts listed above are not manufactured or endorsed by PuroTwist.  Rather, these replacement filters, RO reverse osmosis membranes and replacement parts are manufactured by other companies.  While these replacement water filters, repair parts and reverse osmosis membranes are compatible for use in PuroTwist under counter reverse osmosis drinking water filtration equipment, we make no representation as to whether using these water filter cartridges, replacement parts and RO reverse osmosis membranes is consistent with the warranty and specifications applicable to PuroTwist under sink drinking water system equipment.