Adding an under-sink water filter? Plan the faucet, space and service access

Define which water you want to filter

This project concerns drinking water at a kitchen sink. If your goal includes showers or other taps throughout the home, request a separate whole-house assessment instead of assuming an under-sink unit covers them.

State your water source and the specific result you want. Ask the manufacturer to match the exact model's performance data and operating requirements to that goal. Cartridge count and the word 'filtered' are not evidence that every system addresses the same substances.

Choose how the water will reach your glass

Aquasana's AQ-MF-1 Claryum Direct Connect serves the existing faucet through the cold-water supply. Its instructions specify cold-water use only. This arrangement can avoid adding a second faucet, but the existing connections still need a compatibility check.

The AQ-6200 Claryum 2-Stage uses a dedicated drinking-water faucet. Its shared installation manual specifies a hole at least half an inch across for the supplied faucet. That is a model-specific minimum, not permission to drill any sink. Have the faucet base, countertop material and access underneath reviewed; a separately purchased faucet has its own instructions.

Reserve working space, not just storage space

The AQ-MF-1 manual calls for three inches of clearance beyond the cartridge base for replacement and places the head less than three feet from the cold-water supply. Those requirements help explain why a distant, tightly packed cabinet corner may not work even if the filter body fits.

Aquasana's AQ-SFRO2 SmartFlow reverse-osmosis layout includes a separate water tank as well as the filter assembly. Its instructions require checking both components' positions and keeping the assembly accessible for scheduled changes. Treat the tank, tubing routes and access as part of the footprint; do not compare systems using the filter housing's dimensions alone.

Have the connections reviewed as a complete system

The AQ-SFRO2 also requires a drain connection. Its manual directs the installer to check applicable air-gap or backflow requirements with a licensed plumber. This adds work beyond finding a cold-water connection and a faucet hole. The existing disposal and drain arrangement therefore belong in the assessment.

Ask who will handle any plumbing changes or countertop work and whether those tasks are included in the quote. Leave disconnecting lines, modifying drains and drilling to the appropriately qualified installer; photos and the model manual are enough to begin the discussion.

Prepare a useful request

Include these details without disconnecting anything:

• A photo of the sink deck showing the faucet, sprayer, soap dispenser and any unused hole.
• A wide cabinet photo showing the sink bowls, disposal, drains, valves and pull-out storage.
• The proposed system and faucet model numbers, with links to their instructions.
• Cabinet dimensions, storage you need to retain and rental approval for any proposed alterations.

Plan the handover and ongoing care

Include the manufacturer's startup procedure, leak checks and a demonstration of service access in the agreed work. Keep the exact cartridge part numbers and replacement schedule with the manual. Before restoring your storage baskets, confirm they will not block the planned maintenance space or access to the shutoff.