Companion Undersink Replacement Filter Pack

Please use the dropdown menu above to select the configuration that matches your existing Companion Undersink system:

• 3-Stage System: Standard Companion Undersink configuration
• 4-Stage with Additional Carbon: Companion system with an added carbon filtration stage
• 4-Stage with Nitrate Filter: Companion system with an added nitrate reduction stage

If you’re unsure which configuration you have, feel free to reach out with a photo of your system and we’ll be happy to help identify the correct replacement pack.

Your replacement pack includes the filters needed for the system configuration selected above.

• Stage 1:
  Premium carbon block filtration for chlorine reduction and improved taste and odor.
• Stage 2:
  Advanced electropositive nanofiber filtration designed to capture bacteria, viruses, cysts, and ultrafine particles while maintaining strong flow performance.
• Stage 3:
  Advanced carbon filtration for additional chemical contaminant reduction and final water quality.
• Stage 4 (where applicable):
  An additional carbon filtration or dedicated nitrate reduction cartridge, depending on the system configuration selected.

The replacement filters included in these packs utilize complementary filtration technologies selected for high performance, strong flow, and broad contaminant reduction.

The nanofiber filtration stage uses electropositive filtration technology to capture bacteria, viruses, cysts, and extremely fine particles while maintaining high flow and low pressure drop. The carbon block filtration stages provide additional chlorine, taste, odor, and contaminant reduction.

View Nanofiber Filter Performance Data

View Carbon Block Filter Performance Data

Replace filters every 6–12 months, depending on:

• Water quality
• Usage volume
• Sediment levels in your area

Replacement Guide (PDF)

Sanitization Guide (PDF)

Installation is straightforward with basic household tools. If you’re unsure which replacement pack you need, our team is happy to help.