Choose the filtration you need first. Then find a setup that fits your sink, your daily water use and the upkeep you can manage.

Research updated 4 October 2026 · US edition

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01Start with your water

Read your water supplier’s quality report and identify the contaminant you want to reduce. If you use a private well or do not know your water quality, arrange suitable testing before choosing treatment. This shortlist covers treated drinking water; these filters do not make an unsafe supply safe.

02Check the system and the cartridge together

Look up the exact model and replacement element in the certifier’s directory. Then check the specific reduction claim you need. NSF/ANSI 42, 53 and 401 cover different claims; a standard number alone is not a promise to remove everything. WQA and NSF are the certifiers for the products in this comparison.

03Decide whether non-RO fits the job

These systems use filtration without a reverse-osmosis membrane. Do not choose them on an assumption that they remove fluoride, dissolved salts or hardness. If one of those is your target, look for a treatment system with an explicit matching reduction claim. Our separate reverse-osmosis comparison covers systems with a membrane, drain connection and electrical supply.

04Plan the faucet and cabinet space

All three shortlisted configurations use a separate drinking-water tap and a cold-water feed. Check the faucet opening, plumbing connections, pressure range and access for filter changes before ordering. Aquasana’s linked offers include a brushed-nickel faucet. For Multipure, select the Below-Sink Kit; the base system omits installation hardware. Renters should obtain permission for plumbing or countertop changes.

05Compare flow and replacement timing

A higher rated flow can shorten jug-filling time, but actual flow depends on installation and water conditions. Replace at the stated time or volume limit, whichever arrives first, and sooner when the manual requires it. A filter that still passes water may already be due for replacement.

06Budget beyond the initial system

Compare the complete kit, installation and compatible replacement filters at current prices. For ongoing budgeting, allow two Aquasana sets per year at six-month intervals, or at least one CB6 per year for Aquaversa; capacity and water conditions may require more. Include shipping and any reminder batteries. The starter filter is part of the initial system, so avoid counting it twice. Check auto-delivery terms before subscribing.

Also considering another setup? Compare tankless reverse-osmosis systems.

Sources behind this guide +

• NSF — starting with your water quality report
• NSF — choosing treatment and understanding standards
• Aquasana — current-system installation and care (PDF)
• Multipure — Aquaversa user guide (PDF)
• WQA — Aquasana listing
• NSF — Aquaversa listing