Water Doctor ROS4B Replacement Filter Cartridges – PP / CTO / T33 / RO
In stock and ready to ship
Before you reorder
Match the cartridge, lamp, or filter stage to your existing system before checkout so you do not end up with the wrong replacement part.
Still deciding between replacing a part and solving a broader water problem? Start here first.
Replacement cartridges for the Water Doctor ROS4B system
These Water Doctor ROS4B Replacement Filter Cartridges are designed for the Water Doctor ROS4B 4-stage reverse osmosis system. Choose PP, CTO, T33 or RO depending on the cartridge stage that needs replacement.
Compatible system
- Water Doctor ROS4B 4-Stage RO System
Available cartridges
- PP cartridge for sediment pre-filtration
- CTO cartridge for carbon block filtration
- T33 cartridge for final taste polishing
- RO cartridge for the reverse osmosis stage
Best for
- Customers maintaining an existing ROS4B system
- Replacing one filter stage at a time
- Maintaining flow, taste and routine system performance
Maintenance note
Replacement timing depends on water conditions and household usage. For proper fit, confirm your system model is ROS4B before ordering.
Before ordering
These cartridges are for ROS4B. They are not the same as ROS4A quick-twist cartridges or standard 2.5 x 10 cartridges.
Product prices do not include installation unless the item is specifically sold as an installation service. Products purchased without installation can be delivered separately. When installation is purchased, delivery and installation are scheduled together and are typically completed within 1 week. Accessories and replacement parts are available for shipping or store pickup only. View warranty details.