Keep your water clean and your RO system running strong.
This complete replacement filter set is specifically designed for the Water Doctor ROS4B 4-Stage Reverse Osmosis System. Each cartridge plays a vital role in delivering fresh, purified drinking water to your home.

Included Filters:

• PP Sediment Filter
  Removes rust, sand, dirt, and other large particles
  ➤ Recommended replacement: every 6 months
• CTO Carbon Block Filter
  Removes chlorine, odors, and improves taste
  ➤ Recommended replacement: every 6–12 months
• T33 Post Carbon Filter
  Polishes and enhances water flavor before it reaches your glass
  ➤ Recommended replacement: every 12 months
• RO Membrane Cartridge (TFC, 0.0001 μm precision)
  Filters out bacteria, viruses, heavy metals, and dissolved solids
  ➤ Recommended replacement: every 2–3 years

Quick Twist Design – Easy DIY Installation
Each cartridge is built for quick twist replacement, requiring no tools or plumbing skills. Replace your filters in seconds!

Pure Water Starts with Clean Filters
Ensure optimal performance and maximum protection for your family by replacing filters on schedule.