Complete your Water Doctor ROS4A system with this full set of essential replacement filters.
Specially designed for the Water Doctor ROS4A 4-Stage Reverse Osmosis System, this 4-pack includes all the critical filtration stages to ensure your water stays fresh, clean, and safe.

What’s Included:

1. PP Sediment Filter (Stage 1)
   Captures rust, dirt, sand, and other large particles
   ➤ Recommended Replacement: Every 6 months

2. CTO Carbon Block Filter (Stage 2)
   Removes chlorine, odor, and improves taste
   ➤ Recommended Replacement: Every 6–12 months

3. T33 Post-Carbon Filter (Stage 3)
   Enhances water taste by removing residual impurities
   ➤ Recommended Replacement: Every 12 months

4. RO Membrane Filter (Stage 4)
   Made from premium thin film composite (TFC), filters down to 0.0001 μm
   Removes bacteria, viruses, heavy metals, antibiotics, dissolved salts, and more
   ➤ Recommended Replacement: Every 2–3 years

Quick Twist Installation – No Tools Needed
Each filter is designed with Quick Twist tech for easy, tool-free replacement in just seconds.

NSF-Certified Materials
Built to meet international safety and quality standards, ensuring long-term performance and peace of mind.