Whole-house vs. under-sink water filters
Decide where you need treatment before comparing systems, installation and maintenance.
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Start with the taps you want to treat
A point-of-entry system treats water coming into the home. A point-of-use system treats water at a particular fixture. If you are mainly comparing options for drinking and cooking, start at the kitchen sink. If the concern affects several fixtures, check whole-house options with an installer.
Identify what you want the system to do
Use a local water report or appropriate testing to identify the issue. Taste, odor and appearance alone cannot tell you whether water is safe. Check the exact model’s performance documentation for the substance you are concerned about.
Compare the installation and upkeep
For whole-house equipment, ask about service flow, pressure, plumbing space, shutoffs and drain requirements. For a sink system, measure the cabinet and check the faucet, drain and pressure requirements. Compare replacement part numbers, access and ongoing costs before choosing.
Two systems can have different jobs
A household may want treatment at the incoming main and a different treatment at the kitchen sink. Plan each for a defined issue. Do not assume a whole-house carbon system provides the same dissolved-contaminant reduction as a specified RO system, or that RO output in gallons per day describes the service flow at every tap.
Compare Crystal Quest families within their role
SMART, Eagle and High Flow are whole-house families with different media and sizing decisions. Thunder is an under-sink RO/UF family with C/M and pump variations. Compare each in its own model matrix and price the actual configuration rather than judging from a minimum price or stage count.